Posts Tagged csharp

Database First Development with Entity Framework 5 in Visual Studio 2012

Build and test a Data Access Layer (DAL) using Entity Framework 5 and Database First Development in Visual Studio 2012. Use the Entity Framework Designer to build an ADO.NET Entity Data Model containing database tables, views, stored procedures, and scalar-valued functions. An updated version of this project’s source code, using EF6 is now available on GitHub. The GitHub repository contains all three Entity Framework blog posts.

HealthTracker EDMX Diagram

Introduction

In the last post, we explored Microsoft’s new Entity Framework 5 with Code First Development. In this post, we will explore Entity Framework 5 with Database First Development. We will be using the same data model as before. However, this time instead of POCOs, we will start with a SQL Server 2008 R2 database and use the Entity Framework Designer to build an ADO.NET Entity Data Model (EDM). In addition to database tables, we will look at Entity Framework’s ability to support database views (virtual tables), stored procedures, and scalar-valued functions.

Download a complete copy of the post’s source code, with SQL scripts to create the database objects and populate the database with sample data, from DropBox.

Entity Framework’s Code First and Model First development offer many great options for .NET developers. However, in my experience, most enterprise-level application developers work with a Database First Development model. Using Database First Development, Entity Framework 5 (EF5) provides the ability to construct a powerful yet easy-to-implement data access layer (DAL) between the database and the business logic.

The steps involved in this example are as follows:

  1. Create the new SQL Server database;
  2. Create the database objects;
  3. Create a new C# Class Library Project in Visual Studio 2012 Solution;
  4. Add a new ADO.NET Entity Data Model to project;
  5. Create a new Database Connection;
  6. Import the database objects into the EDM;
  7. Modify the EDM to accommodate the scalar-valued functions;
  8. Populate the database with sample data;
  9. Validate the EDM using a Unit Test Project;

Below is a final view of the entire Solution for reference as you work through the post.

Solution Explorer View of Final Solution

Solution Explorer View of Final Solution

The Database

Using SQL Server 2008 R2 Management Studio (SSMS), Toad for SQL, or similar application, create a new database, named ‘HealthTracker’. I left all the default database settings unchanged for this post.

Create the New Health Tracker Database

Create the New Health Tracker Database

Next, execute the supplied sql script to populate the HealthTracker database with the necessary database objects. The script should insert the following objects: (6) tables, (1) view, (1) stored procedure, (3) scalar-valued functions, and all the necessary table relationships. All objects will be members of the default ‘dbo’ schema.

Database in SQL Server Object Viewer

Database in SQL Server Object Viewer

Barring a few minor changes, this data model is identical to the one we built in the last post using Code First Development with POCOs. The below Database Diagram illustrates the one-to-many relationships between the tables. The tables are pluralized in the database, as opposed to singular in the ADO.NET Entity Data Model (Meals vs. Meal, People vs. Person, etc.). This is a common pattern with Entity Framework.

Database Diagram of Table Relationships

Database Diagram of Table Relationships

Optional: Setting Up Database Credentials

For security and simplicity, I choose to add a new Login, User, and Role to the database. This step is not necessary for this post. However, it is good to get into the habit of securing your database, using database Logins, Users, Roles, and Permissions. In addition, if you are planning to deploy the database and the DAL to other environments such as Test or Production, don’t tie your Solution to personal credentials, a machine-specific account, or to an administrative role in the database with overly broad permissions.

The Database User, DemoUser, is associated with the Login, DemoLogin. DemoUser is a member of the Database Role, DemoRole. I will use the DemoLogin account to connect the EDM to the database. DemoRole has the minimal required database permissions the Entity will need to function: Alter, Insert, Delete, Execute, Select, Update, and View definition. DemoUser only needs Connect permission. Again, this step is optional. You can use your own credentials if you choose.

Included with the downloadable code is a third sql script that should create the User, Role, Login, and required Permissions, if you choose to use them to follow along with the post.

Database Permissions for User and Role

Database Permissions for User and Role

The Data Access Layer

Following good software design principles, we will separate our concerns between Projects. We want to create a Data Access Layer (DAL), to act as an interface between our database and our business logic. We don’t want to interact with the data directly in our DAL Project. By separating the DAL into its own project, we can reference that project’s assembly (.dll) from any other project, be it another class library (our business logic), a WCF service, WPF, Silverlight or console application, or an ASP.NET site. To start, create a new Visual C# Class Library. Name it ‘HealthTracker.DataAccess.DbFirst’. Create a new Solution for the Project in the same dialog box, named ‘HealthTracker’.

New Visual C# Windows Class Library Project

New Visual C# Windows Class Library Project

First, install Entity Framework (System.Data.Entity namespace classes) into the Solution by right clicking on the Solution and selecting ‘Manage NuGet Packages for Solution…’. Install the ‘EntityFramework’ package. If you haven’t discovered the power of NuGet with Visual Studio, check out their site.

Manage NuGet Packages - Install EntityFramework Package

Manage NuGet Packages – Install EntityFramework Package

Next, add a new ‘ADO.NET Entity Data Model’ item, named ‘HealthTracker.edmx’, to the HealthTracker.DataAccess.DbFirst project. According to Microsoft, an .edmx file also contains information used by the ADO.NET Entity Data Model Designer (Entity Designer) to render a model graphically. An .edmx file is the combination of three metadata files: the conceptual schema definition language (CSDL), store schema definition language (SSDL), and mapping specification language (MSL) files. For more information, see .edmx File Overview (Entity Framework).

Adding the ADO.NET Entity Data Model to Project

Adding the ADO.NET Entity Data Model to Project

Adding the ADO.NET Entity Data Model item will start the Entity Data Model Wizard. Since we are exploring Database First Development, select ‘Generate from Database’.

Entity Data Model Wizard - Generate from Database

Entity Data Model Wizard – Generate from Database

Next, we will be prompted to choose a data connection. Since this is the first time we are accessing our newly created HealthTracker database, we need to create a new data connection. Select ‘New Connection…’

Entity Data Model Wizard - Choose Your Data Connection

The options you chose in the ‘Connection Properties’ dialog window, such as the server and instance name, will depend on your own SQL Server configuration and the method you chose to log onto the server. As mentioned before, I will use the ‘DemoLogin’ account. The connection string will reside in the project’s app.config file. Make sure to always chose ‘Test Connection’ to verify you have configured the Data Connection properly.

New Connection - Database Connection Properties

New Connection – Database Connection Properties

Once the data connection is established, we are prompted to add the database objects to the EDM. Only add the objects that we created earlier with the sql script.

Entity Data Model Wizard - Choose Your Database Objects

Entity Data Model Wizard – Choose Your Database Objects

When the import is complete, the EDM should look like the following in the Entity Designer. You should see the six table entities, with one-to-many associations between them, as well as the one view entity, ‘PersonSummaryView’. Each database object you imported is referred to as an entity. Drag the entities into any position you want on the Design surface.

HealthTracker Entity Data Model Diagram

HealthTracker Entity Data Model Diagram

Similarly, when the import is complete, the EDM should look like the following in the Model Browser.

Model Browser - View the of the Entity Data Model

Model Browser – View of the Entity Data Model

Stored Procedures

You recall we imported a stored procedure, ‘GetPersonSummary’. What happened to that object? In the Model Browser, double-click on the GetPersonSummary item under the Function Imports. The stored procedure was imported into the EDM by EF. The results the procedure returns from the database is associated with a new complex object type, ‘GetPersonSummary_Result’.

Function Import - Stored Procedure

Function Import – Stored Procedure

Scalar Functions

If you view the sql code for the above stored procedure, ‘GetPersonSummary’, you will note it calls three scalar-valued functions. These three happen to be the three functions we imported into the EDM. Each function takes a single input parameter, ‘personId’, and returns an integer value – the count of Meals, Activities, and Hydrations for a that Person, based on their Id.

We can also call the scalar-valued functions directly. Unfortunately, in my experience, working scalar-valued functions in Entity Framework is still not as easy as tables, views, and stored procedures. I have found two methods to work with scalar-valued functions. The first method is a bit of hack in my opinion, but it works. The method is documented in several Internet posts, including this one on Stack Overflow.

This method requires some minor changes of the .edmx file’s xml, directly. To do so, right-click on the .edmx file and select ‘Open With…’, ‘XML (Text) Editor’. This is how the functions looks in the .edmx file before changes:

<Function Name="CountActivities" ReturnType="int" Aggregate="false" BuiltIn="false" NiladicFunction="false" IsComposable="false" ParameterTypeSemantics="AllowImplicitConversion" Schema="dbo">
    <Parameter Name="personId" Type="int" Mode="In" />
</Function>
<Function Name="CountHydrations" ReturnType="int" Aggregate="false" BuiltIn="false" NiladicFunction="false" IsComposable="true" ParameterTypeSemantics="AllowImplicitConversion" Schema="dbo">
    <Parameter Name="personId" Type="int" Mode="In" />
</Function>
<Function Name="CountMeals" ReturnType="int" Aggregate="false" BuiltIn="false" NiladicFunction="false" IsComposable="true" ParameterTypeSemantics="AllowImplicitConversion" Schema="dbo">
    <Parameter Name="personId" Type="int" Mode="In" />
</Function>

Remove the ‘ReturnType’ attribute from the <Function /> element. Then, add a <CommandText /> element to each of the <Function /> elements. See the modified .edmx file below for the contents of the <CommandText /> elements.

<Function Name="CountActivities" Aggregate="false" BuiltIn="false" NiladicFunction="false" IsComposable="false" ParameterTypeSemantics="AllowImplicitConversion" Schema="dbo">
    <CommandText>
        SELECT [dbo].[CountActivities] (@personId)
    </CommandText>
    <Parameter Name="personId" Type="int" Mode="In" />
</Function>
<Function Name="CountHydrations" Aggregate="false" BuiltIn="false" NiladicFunction="false" IsComposable="true" ParameterTypeSemantics="AllowImplicitConversion" Schema="dbo">
    <CommandText>
        SELECT [dbo].[CountHydrations] (@personId)
    </CommandText>
    <Parameter Name="personId" Type="int" Mode="In" />
</Function>
<Function Name="CountMeals" Aggregate="false" BuiltIn="false" NiladicFunction="false" IsComposable="true" ParameterTypeSemantics="AllowImplicitConversion" Schema="dbo">
    <CommandText>
        SELECT [dbo].[CountMeals] (@personId)
    </CommandText>
    <Parameter Name="personId" Type="int" Mode="In" />
</Function>

Next, in the Model Browser, right-click on the ‘Function Imports’ folder and select ‘Add Function Import…’ This brings up the ‘Add Function Import’ dialog window. We will import the ‘CountActivities’ scalar-valued function to show this method. Enter the following information in the dialog window and select Save:

Function Import - Scalar-valued Function

Function Import – Scalar-valued Function

You can do the same for the other two scalar-valued functions, if you choose. We will only test the ‘CountActivities’ function, next with our Unit Tests. The downside of this method is the edits to the .edmx file will be lost when you update the EDM from the database. You will have to re-edit the .edmx file each time. This not a great solution.

The second method to call a scalar-valued function uses a feature of Entity Framework 5, the ‘Database.SqlQuery Method (String, Object[])’ Method. According to Microsoft, an instance of this class is obtained from an DbContext object and can be used to manage the actual database backing a DbContext or connection. Using ‘SqlQuery’ method, a raw SQL query that will return elements of the given generic type is created. The type can be any type that has properties that match the names of the columns returned from the query, or can be a simple primitive type.

Below is an example of the method’s use, similar to code in the Unit Test Project we will create next, to test our EDM.

using (HealthTrackerEntities context = new HealthTrackerEntities())
{
    string sqlQuery = "SELECT [dbo].[CountMeals] ({0})";
    Object[] parameters = { 1 };
    int activityCount = db.Database.SqlQuery<int>(sqlQuery, parameters).FirstOrDefault();
}

This method allows us to call the scalar-valued function directly from the database, just as we could any other object using a sql query. The downside of this method is that we are not really taking advantage of the EDM we constructed. It is easier than the first method and it doesn’t need continued changes if we update the EDM. Undoubtedly, there are better methods out there than I have presented here.

Testing the Entity Data Model

To confirm that the EDM is functioning properly, we will create and execute a series of Unit Tests. In reality, although we will be using Visual Studio’s Unit Test Project type, the tests are more like functional tests than true unit tests. This is especially true because we are writing the tests after we have completed development our DAL’s EDM.

We will perform minimal testing of the EDM’s tables, view, stored procedure, and scalar-valued functions, with a series of several simple tests. The tests are only meant to demonstrate the type of tests you could use across all entities in the Model to confirm various functions.

Sample Data

In SSMS or VS2012, execute the supplied sql script that populates the database with test data. The script contains a variety of Meal Types, Activity Types, People, Meals, Activities, and Hydrations table records. Note the script deletes all existing data from those tables. Below is a sample of the Meal table’s sample data.

Sample Meal Data

Sample Meal Data

The Unit Test Project

After adding the sample data to the HealthTracker database, add a new Visual Studio 2012 Unit Test Project, named ‘HealthTracker.UnitTests’, to the ‘HealthTracker’ Solution.

Add New Unit Test Project to Solution

Add New Unit Test Project to Solution

Next, add a Reference to the Unit Test Project from our DAL, the ‘HealthTracker.DataAccess.DbFirst’ Project. This step adds the ‘HealthTracker.DataAccess.DbFirst.dll’ assembly to our Unit Test Project.

Add Entity Data Model Project Reference to Unit Test Project

Add Entity Data Model Project Reference to Unit Test Project

Next, we need to add the same Database Connection we used in the ‘HealthTracker.DataAccess.DbFirst’ Project, to this Project. I always forget this step and end up with a database connection error the first time I try to run a new project. Right-click on the Unit Test Project and select ‘Add New Item…’ Add an ‘Application Configuration File’ item, named ‘app.config’, to the Unit Test Project.

Add Application Configuration File to Unit Test Project

Add Application Configuration File to Unit Test Project

Open the corresponding Application Configuration File in the ‘HealthTracker.DataAccess.DbFirst’ Project and copy the <connectionStrings /> element to our Unit Test Project’s app.config file. The file’s contents should look similar to the following when complete (note, your ‘connectionString’ attribute will have different values).

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
    <connectionStrings>
        <add name="HealthTrackerEntities" connectionString="metadata=res://*/HealthTracker.csdl|res://*/HealthTracker.ssdl|res://*/HealthTracker.msl;provider=System.Data.SqlClient;provider connection string=&quot;data source=gstafford-windows-laptop\DEVELOPMENT;initial catalog=HealthTracker;persist security info=True;user id=DemoLogin;password=DemoLogin123;MultipleActiveResultSets=True;App=EntityFramework&quot;" providerName="System.Data.EntityClient" />
    </connectionStrings>
</configuration>

Lastly, rename the default ‘UnitTest’ class in the Unit Test Project to ‘HealthTrackerUnitTests’. Enter or copy and paste the contents of the supplied HealthTrackerUnitTests.cs file to this file. The supplied file contains all the unit tests.

using System.Linq;
using Microsoft.VisualStudio.TestTools.UnitTesting;
using HealthTracker.DataAccess.DbFirst;

namespace HealthTracker.UnitTests
{
    [TestClass]
    public class HealthTrackerUnitTests
    {
        private const string PersonOriginal = "John Doe";
        private const string PersonNew = "New Person";
        private const string PersonNameUpdated = "Updated Name";

        /// <summary>
        /// Delete any non-sample People from the database created by previous tests
        /// </summary>
        [TestInitialize]
        public void RemoveNonSamplePeople()
        {
            using (var db = new HealthTrackerEntities())
            {
                var peopleToDelete = db.People
                    .Where(person => person.PersonId > 4);

                foreach (var personToDelete in peopleToDelete)
                {
                    db.People.Remove(personToDelete);
                }
                db.SaveChanges();
            }
        }

        /// <summary>
        /// Return the count of People in the database, which should be 4.
        /// </summary>
        [TestMethod]
        public void PersonCountTest()
        {
            using (var db = new HealthTrackerEntities())
            {
                var personCount = (db.People.Select(p => p)).Count();
                Assert.IsTrue(personCount > 0);
            }
        }

        /// <summary>
        /// Return the PersonId of 'John Doe', which should be is 1.
        /// </summary>
        [TestMethod]
        public void PersonIdTest()
        {
            using (var db = new HealthTrackerEntities())
            {
                var personId = db.People
                    .Where(person => person.Name == PersonOriginal)
                    .Select(person => person.PersonId)
                    .First();
                Assert.AreEqual(1, personId);
            }
        }
        /// <summary>
        /// Insert a new Person into the database.
        /// </summary>
        [TestMethod]
        public void PersonAddNewTest()
        {
            using (var db = new HealthTrackerEntities())
            {
                // Setup test
                db.People.Add(new Person { Name = PersonNew });
                db.SaveChanges();

                // Test 1
                var personCount = (db.People.Select(p => p)).Count();
                Assert.AreEqual(5, personCount);

                // Test 2
                var newPersonFound = db.People.FirstOrDefault(
                    person => person.Name == PersonNew);
                Assert.IsNotNull(newPersonFound);
            }
        }

        /// <summary>
        /// Update a Person's name in the database.
        /// </summary>
        [TestMethod]
        public void PersonUpdateNameTest()
        {
            using (var db = new HealthTrackerEntities())
            {
                // Setup test
                var personToUpdate = db.People.FirstOrDefault(
                    person => person.Name == PersonOriginal);

                if (personToUpdate != null) personToUpdate.Name = PersonNameUpdated;
                db.SaveChanges();

                // Test
                var updatedPerson = db.People.FirstOrDefault(
                    person => person.Name == PersonNameUpdated);
                Assert.IsNotNull(updatedPerson);

                // Tear down test
                var personToRevert = db.People.FirstOrDefault(
                    person => person.Name == PersonNameUpdated);

                if (personToRevert != null) personToRevert.Name = PersonOriginal;
                db.SaveChanges();
            }
        }

        /// <summary>
        /// Return the Meal count from PersonSummaryViews database view, which should be 21.
        /// </summary>
        [TestMethod]
        public void PersonSummaryViewTest()
        {
            using (var db = new HealthTrackerEntities())
            {
                var mealCount = (db.PersonSummaryViews
                    .Where(p => p.PersonId == 1)
                    .Select(p => p.MealsCount))
                    .First();
                Assert.AreEqual(21, mealCount);
            }
        }

        /// <summary>
        /// Call CountActivities scalar-valued function directly from in the database.
        /// </summary>
        [TestMethod]
        public void ActivtyCountFunctionFromDatabaseTest()
        {
            using (var db = new HealthTrackerEntities())
            {
                object[] parameters = { 1 };
                var activityCount = db.Database.SqlQuery<int>(
                    "SELECT [dbo].[CountActivities] ({0})",
                    parameters).FirstOrDefault();
                Assert.AreEqual(7, activityCount);
            }
        }

        /// <summary>
        /// Call CountActivities scalar-valued function from the Entity Data Model.
        /// </summary>
        [TestMethod]
        public void ActivtyCountFunctionFromEntityTest()
        {
            using (var db = new HealthTrackerEntities())
            {
                var activityCount = db.CountActivities(1).First();
                if (activityCount != null) activityCount = activityCount.Value;
                Assert.AreEqual(7, activityCount);
            }
        }
    }
}

When complete, build the Solution. Then finally, from the Test menu in the top Visual Studio menu bar, or by right clicking on the ‘HealthTrackerUnitTests’, run all Unit Tests. The test results should look like the following.

Test Explorer Showing Results of Unit Tests

Test Explorer Showing Results of Unit Tests

Conclusion

Congratulations, we have built and tested a Data Access Layer using Entity Framework 5. The DAL can now be referenced from a middle-tier business assemble, WCF Service, or directly from a client application.

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First Impressions of Code First Development with Entity Framework 5 in Visual Studio 2012

Build a Data Access Layer (DAL) in Visual Studio 2012 using the recently-released Entity Framework 5 with Code First Development. Leverage Entity Framework 5’s eagerly anticipated enum support, as well as Code First Migrations and Lazy Loading functionality. An updated version of this project’s source code, using EF6 is now available on GitHub. The GitHub repository contains all three Entity Framework blog posts.

Introduction

In August of this year (2012), along with the release of Visual Studio 2012, Microsoft announced the release of Entity Framework 5 (EF5). According to Microsoft, “Entity Framework (EF) is an object-relational mapper that enables .NET developers to work with relational data using domain-specific objects. It eliminates the need for most of the data-access code that developers usually need to write.

EF5 offers multiple options for development, including Model First, Database First, and Code First. Code First, first introduced in EF4.1, allows you to define your model using C# or VB.Net POCO classes. Additional configuration can optionally be performed using attributes on your classes and properties or by using a fluent API. Code First will then create a database if it doesn’t exist, or Code First will use an existing empty database, adding new tables, according to Microsoft.

Exploring Code First

I started by looking at EF5’s Code First development to create a new database. I chose to create a Data Access Layer (DAL) for a health tracker application. This was loosely based on a mobile application I developed some time ago. You can track food intake, physical activities, and how much water you drink per day.

To further explore EF5’s new enum support feature, I substituted two of the database tables, containing static ‘system’ data, for enumeration classes. Added in EF5, Enumeration (enum) support, was the number one user-requested EF feature. Also added to EF5 were spatial data types and my personal favorite, table-valued functions (TVF).

Once the new database was created, I tested another newer EF feature, Code First Migrations. Code First Migrations, introduced in EF4.3, is a feature that allows a database created by Code First to be incrementally changed as your Code First model evolves.

Creating the HealthTracker DAL

Final View of Both Projects in Solution

Final View of Both Projects in Solution

Here are the steps I followed to create my EF5 Entity Framework DAL project:

1. Create a new C# Class Library, ‘HealthTracker.DataAccess’, in a Solution, ‘HealthTracker’. Target the .NET Framework 4.5.

New Class Library

New Class Library

2. Create (4) POCO (Plain Old CLR Object) classes: Person, Activity, Meal, and Hydration, shown below. Note the virtual properties. According to Microsoft, this enables the Lazy Loading feature of Entity Framework. Lazy Loading means that the contents of these properties will be automatically loaded from the database when you try to access them.

using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.Linq;

namespace HealthTracker.DataAccess.Classes
{
    public class Person
    {
        public int PersonId { get; set; }
        public string Name { get; set; }
        public virtual List<Meal> Meals { get; set; }
        public virtual List<Activity> Activities { get; set; }
        public virtual List<Hydration> Hydrations { get; set; }
    }
}
using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.Linq;

namespace HealthTracker.DataAccess.Classes
{
    public class Activity
    {
        public int ActivityId { get; set; }
        public DateTime Date { get; set; }
        public ActivityType Type { get; set; }
        public string Notes { get; set; }
        public int PersonId { get; set; }
        public virtual Person Person { get; set; }
    }
}
using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.Linq;

namespace HealthTracker.DataAccess.Classes
{
    public class Hydration
    {
        public int HydrationId { get; set; }
        public DateTime Date { get; set; }
        public int Count { get; set; }
        public int PersonId { get; set; }
        public virtual Person Person { get; set; }
    }
}
using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.Linq;

namespace HealthTracker.DataAccess.Classes
{
    public class Meal
    {
        public int MealId { get; set; }
        public DateTime Date { get; set; }
        public MealType Type { get; set; }
        public string Description { get; set; }
        public int PersonId { get; set; }
        public virtual Person Person { get; set; }
    }
}

3. Add data annotations to the POCO classes. Annotations are used to specify validation for fields in the data model. Data annotations can include required, min, max, string length, and so forth. Annotations are part of the System.ComponentModel.DataAnnotations namespace. As an alternative to annotations, you can use the Code First Fluent API.

using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.Linq;

namespace HealthTracker.DataAccess.Classes
{
    public class Person
    {
        public int PersonId { get; set; }

        [Required]
        [StringLength(100,
        ErrorMessage = "Name must be less than 100 characters."),
        MinLength(2,
        ErrorMessage = "Name must be less than 2 characters.")]
        public string Name { get; set; }

        public virtual List<Meal> Meals { get; set; }
        public virtual List<Activity> Activities { get; set; }
        public virtual List<Hydration> Hydrations { get; set; }
    }
}
using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.Linq;

namespace HealthTracker.DataAccess.Classes
{
    public class Activity
    {
        public int ActivityId { get; set; }

        [Required]
        public DateTime Date { get; set; }

        [Required]
        [EnumDataType(typeof(ActivityType))]
        public ActivityType Type { get; set; }

        [StringLength(100,
        ErrorMessage = "Note must be less than 100 characters.")]
        public string Notes { get; set; }

        [Required]
        public int PersonId { get; set; }
        public virtual Person Person { get; set; }
    }
}
using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.Linq;

namespace HealthTracker.DataAccess.Classes
{
    public class Hydration
    {
        public int HydrationId { get; set; }

        [Required]
        public DateTime Date { get; set; }

        [Required]
        [Range(0, 20,
        ErrorMessage = "Hydration amount must be between 0 - 20.")]
        public int Count { get; set; }

        [Required]
        public int PersonId { get; set; }
        public virtual Person Person { get; set; }
    }
}
using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.Linq;

namespace HealthTracker.DataAccess.Classes
{
    public class Meal
    {
        public int MealId { get; set; }

        [Required]
        public DateTime Date { get; set; }

        [Required]
        [EnumDataType(typeof(MealType))]
        public MealType Type { get; set; }

        [StringLength(100,
        ErrorMessage = "Description must be less than 100 characters.")]
        public string Description { get; set; }

        [Required]
        public int PersonId { get; set; }
        public virtual Person Person { get; set; }
    }
}

4. Create (2) enum classes: MealType and ActivityType, shown below.

using System;
using System.Collections.Generic;
using System.Linq;

namespace HealthTracker.DataAccess.Classes
{
    public enum ActivityType
    {
        Treadmill,
        Jogging,
        WeightTraining,
        Biking,
        Aerobics,
        Other
    }
}
using System;
using System.Collections.Generic;
using System.Linq;

namespace HealthTracker.DataAccess.Classes
{
    public enum MealType
    {
        Breakfast,
        MidMorning,
        Lunch,
        MidAfternoon,
        Dinner,
        Snack,
        Brunch,
        Other
    }
}

5. Add Entity Framework (System.Data.Entity namespace classes) to the Solution by right-clicking on the Solution and selecting ‘Manage NuGet Packages for Solution…’ Install the ‘EntityFramework’ package. If you haven’t discovered the power of NuGet with Visual Studio, check out their site.

Manage NuGet Packages - Add Entity Framework

Manage NuGet Packages – Add Entity Framework

6. Add a DbContext class, ‘HealthTrackerContext’, shown below. According to Microsoft, “DbContext represents a combination of the Unit-Of-Work and Repository patterns and enables you to query a database and group together changes that will then be written back to the store as a unit.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Data.Entity;
using HealthTracker.DataAccess.Classes;

namespace HealthTracker.DataAccess
{
    public class HealthTrackerContext : DbContext
    {
        public DbSet<Activity> Activities { get; set; }
        public DbSet<Hydration> Hydrations { get; set; }
        public DbSet<Meal> Meals { get; set; }
        public DbSet<Person> Persons { get; set; }
    }
}

7. Add ‘Code First Migrations’ by running the Enable-Migrations command in the NuGet Package Manager Console. This allowed me to make changes to POCO classes, while keeping the database schema in sync. This only needs to be run once.

Enable-Migrations -ProjectName HealthTracker.DataAccess -Force -EnableAutomaticMigrations -Verbose
Package Manager Console - Code First Migrations

Package Manager Console – Code First Migrations

This creates the following class in a new Migrations folder, called Configuration.cs

namespace HealthTracker.DataAccess.Migrations
{
    using System;
    using System.Data.Entity;
    using System.Data.Entity.Migrations;
    using System.Linq;

    internal sealed class Configuration : DbMigrationsConfiguration<HealthTracker.DataAccess.HealthTrackerContext>
    {
        public Configuration()
        {
            AutomaticMigrationsEnabled = true;
        }

        protected override void Seed(HealthTracker.DataAccess.HealthTrackerContext context)
        {
            //  This method will be called after migrating to the latest version.

            //  You can use the DbSet<T>.AddOrUpdate() helper extension method
            //  to avoid creating duplicate seed data. E.g.
            //
            //    context.People.AddOrUpdate(
            //      p => p.FullName,
            //      new Person { FullName = "Andrew Peters" },
            //      new Person { FullName = "Brice Lambson" },
            //      new Person { FullName = "Rowan Miller" }
            //    );
            //
        }
    }
}

Running the Update-Database command in Package Manager Console updates the database when you have made changes.

Update-Database -ProjectName HealthTracker.DataAccess -Verbose -Force

I found the Code First Migrations feature a bit confusing at first. It took several tries to work out the correct command to use to add Code First Migrations to my data access project, and the command to call later, to update the database based on my project.

Dependency Graph

Here is the way the class relationships should look using Visual Studio 2012’s powerful new Dependency Graph feature:

Visual Studio 2012 Dependency Graph of HealthTracker

Visual Studio 2012 Dependency Graph of HealthTracker

Testing the Project

To test the entities, I created a simple console application, which references the above EF5 class library. The application takes a person’s name as input. It then adds and/or updates Activities, Meals, and Hydrations, for that Person, depending on whether or not that Person already exists in the database.

1. Create a new C# Console Application, ‘HealthTracker.Console’.

New Console Application

New Console Application

2. Add a reference to the ‘HealthTracker.DataAccess’ project.

Add Reference to HealthTracker.DataAccess Project

Add Reference to HealthTracker.DataAccess Project

3. Create the Examples class and add the code below to the Main method class. As seen in the Examples class, using Micorsoft’s LINQ to Entities with the new .NET Framework 4.5, makes querying the entities very easy.

using System;

namespace HealthTracker.ConsoleApp
{
    class Program
    {
        private static string _newName = String.Empty;

        static void Main()
        {
            GetNameInput();
            var personId = Examples.FindPerson(_newName);

            if (personId == 0)
            {
                Examples.CreatePerson(_newName);
                personId = Examples.FindPerson(_newName);
            }

            Examples.CreateActivity(personId);
            Examples.CreateMeals(personId);
            Examples.UpdateOrAddHydration(personId);

            Console.WriteLine("Click any key to quit.");
            Console.ReadKey();
        }

        private static void GetNameInput()
        {
            Console.Write("Input Person's Name: ");
            var readLine = Console.ReadLine();
            if (readLine != null) _newName = readLine.Trim();
            if (_newName.Length > 2) return;
            Console.WriteLine("Name to short. Exiting program.");
            GetNameInput();
        }
    }
}
using System;
using System.Globalization;
using System.Linq;
using HealthTracker.DataAccess;
using HealthTracker.DataAccess.Classes;

namespace HealthTracker.ConsoleApp
{
    public class Examples
    {
        private static readonly DateTime Today = DateTime.Now.Date;

        /// <summary>
        /// Example of finding a Person in database.
        /// </summary>
        /// <param name="name">Name of the Person</param>
        /// <returns>Person's unique PersonId</returns>
        public static int FindPerson(string name)
        {
            using (var db = new HealthTrackerContext())
            {
                var personId = db.Persons.Where(person => person.Name == name)
                    .Select(person => person.PersonId).FirstOrDefault();

                if (personId == 0)
                    Console.WriteLine("Person, {0}, could not be found...", name);
                else
                    Console.WriteLine("PersonId {0} retrieved...", personId);

                return personId;
            }
        }

        /// <summary>
        /// Example of Adding a new Person
        /// </summary>
        /// <param name="name">Name of the Person</param>
        public static void CreatePerson(string name)
        {
            using (var db = new HealthTrackerContext())
            {
                // Add a new Person
                db.Persons.Add(new Person { Name = name });
                db.SaveChanges();
                Console.WriteLine("New Person, {0}, added...", name);
            }
        }

        /// <summary>
        /// Example of updating existing Hydration count.
        /// Else adding new Hydration if it doesn't exist.
        /// </summary>
        /// <param name="personId">Person's unique PersonId</param>
        public static void UpdateOrAddHydration(int personId)
        {
            using (var db = new HealthTrackerContext())
            {
                var existingHydration = db.Hydrations.FirstOrDefault(
                    hydration => hydration.PersonId == personId
                        && hydration.Date == Today);

                if (existingHydration != null && existingHydration.HydrationId > 0)
                {
                    existingHydration.Count++;
                    db.SaveChanges();
                    Console.WriteLine("Existing Hydration count increased to {0}...",
                        existingHydration.Count.ToString(CultureInfo.InvariantCulture));
                    return;
                }

                db.Hydrations.Add(new Hydration
                {
                    PersonId = personId,
                    Date = Today,
                    Count = 1
                });
                db.SaveChanges();
                Console.WriteLine("New Hydration added...");
            }
        }

        /// <summary>
        /// Example of adding two Meals.
        /// </summary>
        /// <param name="personId">Person's unique PersonId</param>
        public static void CreateMeals(int personId)
        {
            using (var db = new HealthTrackerContext())
            {
                db.Meals.Add(new Meal
                {
                    PersonId = personId,
                    Date = Today,
                    Type = MealType.Breakfast,
                    Description = "(2) slices toast, (1) glass orange juice"
                });

                db.Meals.Add(new Meal
                {
                    PersonId = personId,
                    Date = Today,
                    Type = MealType.Lunch,
                    Description = "(1) protein shake, (1) apple"
                });

                db.SaveChanges();
                Console.WriteLine("Two new Meals added...");
            }
        }

        /// <summary>
        /// Example of adding an Activity
        /// </summary>
        /// <param name="personId">Person's unique PersonId</param>
        public static void CreateActivity(int personId)
        {
            using (var db = new HealthTrackerContext())
            {
                db.Activities.Add(new Activity
                {
                    PersonId = personId,
                    Date = Today,
                    Type = ActivityType.Treadmill,
                    Notes = "30 minutes, 500 calories"
                });

                db.SaveChanges();
                Console.WriteLine("New Activity added...");
            }
        }
    }
}

The console output below demonstrates the addition a new Person, Susan Jones, with an associated Activity, two Meals, and a Hydration.

Console Output - Adding New Person

Console Output – Adding New Person

The console output below demonstrates inputting Susan Jones a second time. Observe what happened to the output.

Console Output - Updating Existing Person

Console Output – Updating Existing Person

Below is a view of the newly created SQL Express ‘HealthTracker.DataAccess.HealthTrackerContext’ database. Note the four database tables, which correspond to the four POCO classes in the project. Why did the database show up in SQL Express or LocalDB? Read the ‘Where’s My Data?‘ section of this tutorial by Microsoft. Code First uses SQL Express or LocalDB by default, but you add a connection to your project to target SQL Server.

View of HealthTracker SQL Express Database

View of HealthTracker SQL Express Database

You can switch your connection SQL Server at anytime, even after the SQL Express or LocalDB database has been created, and updated using Code First Migrations. That’s what I chose to do after completing this post’s example. I prefer doing my initial development with a temporary SQL Express or LocalDB database while the entities and database schema are still evolving. Once I have the model a fairly stable point, I create the SQL Server database, and continue from there evolving the schema.

Conclusion

Having worked with earlier editions of Entity Framework’s Database First and Model First development, in addition to other ORM packages, I was impressed with EF5’s new features as well as the Code First development methodology. Overall, I feel EF5 is another big step toward making Entity Framework a top-notch ORM, on par with other established products on the market.

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