This section describes how to use the Entity Data Model wizard to create the .edmx file and execute queries.
Install and Set Up Entity Framework
Install Entity Framework or add references to the required assemblies for your chosen version of Entity Framework. The assemblies are located in the lib subfolder of the installation directory. See Using EF 6 for using Entity Framework 6 (EF6). See Installed Assemblies for more information about all assemblies shipped with the provider
Add a Data Connection in Server Explorer
Before you can create an Entity Data Model, you will need to create a data connection. To do this,
- Navigate to Server Explorer -> right click "Data Connections" -> Add Connection...
- Click the Change button beside the Data Source box.
- Select CData HDFS Data Source, then click OK.
- Configure your connection settings, then click OK.
Add a New Item To Your Project
In the Visual Studio Solution Explorer, right-click your project and click Add > New Item.
Create an ADO.NET Entity Data Model
In the resulting Add New Item dialog, click ADO.NET Entity Data Model and enter an appropriate title, such as "HDFSEntityDataModel.edmx".
Use the Entity Data Model Wizard
Complete the following steps to create the .edmx file with the Entity Data Model wizard:
- On the first page, select Generate from database.
- On the next page, select the data provider connection you want to use with your project or create a new connection.
Set the CacheLocation and CacheMetadata connection properties to cache table metadata. Setting these connection properties is necessary to make generating the Entity Framework model more efficient. To learn about this process, see Caching Metadata.
- Select whether to include sensitive data (such as passwords) in the connection string. Note that the option to exclude sensitive data means password fields are not copied to the generated config file with the rest of the connection string properties.
- Select the box to save the entity connection settings in App.Config, and enter a name for the context class of the data connection; for example, "HDFSEntities".
After Visual Studio retrieves the necessary information from the live data source, the wizard presents a listing of database objects you can include in your project. Note that this step may take several minutes as Visual Studio retrieves table schemas from HDFS.
Perform LINQ Commands in Your Code
You are now ready to start using LINQ in your code.
HDFSEntities context = new HDFSEntities(); var FilesQuery = from Files in context.Files orderby Files.ChildrenNum select Files;
Note: Be sure to declare "using System.Linq" in your file.