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EntityConnection Constructor (String)

EntityConnection Constructor (String)

Initializes a new instance of the EntityConnection class, based on the connection string.

Namespace:  System.Data.EntityClient
Assembly:  System.Data.Entity (in System.Data.Entity.dll)

public EntityConnection(
	string connectionString
)

Parameters

connectionString
Type: System.String

The provider-specific connection string.

ExceptionCondition
ArgumentException

An invalid connection string keyword has been provided, or a required connection string keyword has not been provided.

The Entity Data Model tools generate a named connection string that is stored in the application's configuration file. This named connection string can be supplied in place of the connectionString parameter when instantiating the EntityConnection class.

To avoid inadvertently putting objects System.Data.Common.CommandTrees and ObjectContext out of sync with their metadata, EntityConnection must lock its metadata. No changes to the connection string are allowed after the metadata is locked. The following are two scenarios in which metadata is locked:

  • The EntityConnection instance is constructed through the default constructor, or through this constructor (EntityConnection(String)), which accepts a connection string. In either case the connection string might be changed multiple times before the connection is opened. Calling [M:System.Data.EntityClient.EntityConnection.Open()] or [M:System.Data.EntityClient.EntityConnection.GetMetadataWorkspace()] locks the metadata.

  • The EntityConnection instance is constructed through the EntityConnection(MetadataWorkspace, DbConnection) constructor, which accepts a MetadataWorkspace and a DbConnection. In this case the metadata is locked at construction time. No changes to the connection string are ever allowed.

When metadata is loaded, the EntityConnection verifies that the conceptual model, the storage model, and the mapping file are all present.

For code examples, see Working with EntityClient.

Windows 7, Windows Vista, Windows XP SP2, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5 SP1

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