The latest ADO.NET evolution focuses on raising the level of abstraction from the logical (relational) level to the conceptual (entity) level. For this purpose Microsoft introduces the Entity Framework, designed to simplify data - object conversion and embed data access queries into program code.

dotConnect for PostgreSQL fully supports ADO.NET Entity Framework, including Entity Framework Core.

The article consists of the following sections:

• What is ADO.NET Entity Framework?
• Entity Framework Support Key Features
• Using the Entity Data Provider
• Using the Entity Data Provider with Entity Framework v6
• Using the Entity Data Provider with Entity Framework 6.4
• Using the Entity Data Provider with Entity Framework Core
• Deploying an Entity Framework Project
• Compatibility and Requirements
• Migration between ADO.NET Entity Data Model (*.edmx) and Devart Entity Model (*.edml)

What is ADO.NET Entity Framework?

The Entity Framework is a set of technologies in ADO.NET that support development of data-oriented software applications. The Entity Framework is designed to enable developers to create data access applications by programming against a conceptual application model instead of programming directly against a relational storage schema. The goal is to decrease the amount of code and maintenance required for data-oriented applications. Entity Framework applications provide the following benefits:

• Applications can work in terms of a more application-centric conceptual model, including types with inheritance, complex members, and relationships.
• Applications are freed from hard-coded dependencies on a particular data engine or storage schema.
• Mappings between the conceptual model and the storage-specific schema can change without changing the application code.
• Developers can work with a consistent application object model that can be mapped to various storage schemas, possibly implemented in different data sources.
• Multiple conceptual models can be mapped to a single storage schema.
• Language-integrated query support provides compile-time syntax validation for queries against a conceptual model.

Entity Framework Support Key Features

• Conceptual approach to enterprise development
• High performance
• Wide support for LINQ to Entities
• Wide support for EntitySQL
• Full CRUD (Create, Retrieve, Update, Delete) support
• Wide support for server data types
• Capability to use stored procedures when manipulating data
• Stored procedure import support
• Visual Studio EDM Wizard support (reverse engineering of database objects to entity model)
• Visual Studio LightSwitch support
• Generate Database Wizard (Model-First) support
• Configurable Code-First CreateDatabase/DatabaseExists/DropDatabase functionality support
• Support for Code-First Migrations with database-specific features
• Entity Framework Spatials support
• Support for database-specific system functions in LINQ to Entities and Entity SQL
• Full-text search support
• Batch updates
• Entity Framework provider configuration

Using the Entity Data Provider

dotConnect for PostgreSQL allows using it in Entity Framework models in various ways. You can use our provider with standard Visual Studio Entity Framework tools, in the same way as SqlClient.

For example, you can create an Entity Framework model, using database-first approach (for Entity Framework v1 - v6) in the following way:

1. Open your project.
2. Add new item ADO.NET Entity Data Model to your project and specify its name.
3. Choose Generate from database.
4. Choose the dotConnect you use as data provider and specify the connection string.
5. Select tables that are actually used in your project and click Generate to finish the process. If the selected tables contain foreign keys, they will be reflected in the generated models as well.
6. Specify a name for the model namespace. Note that this name should be different from the database (schema) name.

dotConnect for PostgreSQL also provides advanced ORM designer and code generation tool - Entity Developer. It allows creating Entity Framework v1 and Entity Framework Core models using database-first, model-first, or mixed approaches and generating code for them.

For your convenience there is a brief Entity Framework Tutorial that you can use to get acquainted with the technology. You can also take a look at Entity Framework samples available with the product, or download separate Entity Framework Query Samples package. The latter is a standard Microsoft demo with added PostgreSQL connectivity.

dotConnect for PostgreSQL also supports Visual Studio LightSwitch, so you can develop LightSwitch applications with our provider. You can find a tutorial on creating a simple LightSwitch application using dotConnect for PostgreSQL here: Tutorial: How to Connect Visual Studio LightSwitch to PostgreSQL with dotConnect for PostgreSQL Data Provider.

Using the Entity Data Provider with Entity Framework v6

Since there are no global Entity Framework provider registration for Entity Framework v6, you should register our provider manually in the config file of your project. For this you should add the following line:

<provider invariantName="Devart.Data.PostgreSql" type="Devart.Data.PostgreSql.Entity.PgSqlEntityProviderServices, 
Devart.Data.PostgreSql.Entity.EF6, Version=7.1.26.0, Culture=neutral, PublicKeyToken=09af7300eec23701" />

to the entityFramework -> providers section.

<entityFramework>
    <providers>
      <provider invariantName="Devart.Data.PostgreSql" type="Devart.Data.PostgreSql.Entity.PgSqlEntityProviderServices, 
      Devart.Data.PostgreSql.Entity.EF6, Version=7.1.26.0, Culture=neutral, PublicKeyToken=09af7300eec23701" />
    </providers>
</entityFramework>

Note: replace 7.1.26.0 with the actual assembly version.

If it suits for your project, you may omit the exact assembly version:

<entityFramework>
    <providers>
        <provider invariantName="Devart.Data.PostgreSql" type="Devart.Data.PostgreSql.Entity.PgSqlEntityProviderServices, Devart.Data.PostgreSql.Entity.EF6" />
    </providers>
</entityFramework>

This section appears in the project config file only after you add the NuGet EntityFramework package either explicitly, by executing the "install-package EntityFramework" command, or implicitly, by adding an Entity Framework v6 model for SQL Server via EDM Wizard.

Using the Entity Data Provider with Entity Framework 6.4

dotConnect for PostgreSQL fully supports Entity Framework 6.4 on .NET Core 3 (and on Full .NET Framework).

For Entity Framework 6.4, an Entity Framework provider cannot be registered in the config file of your project. You need to use any of the following two code-based approaches:

• The first approach is to use the DbConfigurationType attribute. It suits only for DbContext. Here is an example:

  • C#

    [DbConfigurationType(typeof(Devart.Data.PostgreSql.Entity.PgSqlEntityProviderServicesConfiguration))]
    public class MyContext : DbContext {
   
      // ...
    }
  

• The second way is to use the static SetConfiguration method of the DbConfiguration class. It can be used both with DbContext and ObjectContext. Here is an example:

  • C#

    public class MyContext: ObjectContext {
   
      static MyContext() {
   
        DbConfiguration.SetConfiguration(new Devart.Data.PostgreSql.Entity.PgSqlEntityProviderServicesConfiguration());
      }
   
      // ...
    }
  

Both of the above examples use the PgSqlEntityProviderServicesConfiguration class that suites for most users. If Entity Framework 6.4 provider configuration must be customized, you will need to create a descendant of the DbConfiguration class and set values for SetProviderFactory() and SetProviderServices() in it. Then use this custom class for provider registration. Here is an example: