EF6 DBContext 动态连接字符串

Question

public partial class ProcessContext : DbContext
{
    static ProcessContext()
    {
        Database.SetInitializer<ProcessContext>(null);
    }

    public ProcessContext()
        : base("Name=ProcessCS") //Comes from Config File
    {
    }

    --DBSets 
    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
       --Code
    }
}

这是一个多租户数据库，我们有 3 个不同的数据库。集中式数据库位于公共位置，不会更改。这是存储其余数据库详细信息的地方。我需要创建连接字符串@runtime，详细信息将来自这个集中式数据库。有人可以告诉我怎么做吗？

我尝试使用以下代码，但它不起作用。这里会调用这个方法

public ProcessContext()
    : base(nameOrConnectionString: ConnectionString())
{
}

private static string ConnectionString()
{
    SqlConnectionStringBuilder sqlBuilder = new SqlConnectionStringBuilder();
    sqlBuilder.DataSource = "XXX";
    sqlBuilder.InitialCatalog = "YYY";
    sqlBuilder.PersistSecurityInfo = true;
    sqlBuilder.IntegratedSecurity = true;
    sqlBuilder.MultipleActiveResultSets = true;

    EntityConnectionStringBuilder entityBuilder = new EntityConnectionStringBuilder();
    entityBuilder.ProviderConnectionString = sqlBuilder.ToString();
    entityBuilder.Metadata = "res://*/";
    entityBuilder.Provider = "System.Data.SqlClient";

    return entityBuilder.ToString();
}

Answer 1

对于 SQL Server 连接，覆盖实体容器类：（适用于 EF6、SQL server 2012 express、VS2013）

public partial class PxxxxEntities
{
    private PxxxxEntities(string connectionString)
        : base(connectionString)
    {
    }

    public static PxxxxEntities ConnectToSqlServer(string host, string catalog, string user, string pass, bool winAuth)
    {
        SqlConnectionStringBuilder sqlBuilder = new SqlConnectionStringBuilder
        {
            DataSource = host,
            InitialCatalog = catalog,
            PersistSecurityInfo = true,
            IntegratedSecurity = winAuth,
            MultipleActiveResultSets = true,

            UserID = user,
            Password = pass,
        };

        // assumes a connectionString name in .config of MyDbEntities
        var entityConnectionStringBuilder = new EntityConnectionStringBuilder
        {
            Provider = "System.Data.SqlClient",
            ProviderConnectionString = sqlBuilder.ConnectionString,
            Metadata = "res://*/DbModel.csdl|res://*/DbModel.ssdl|res://*/DbModel.msl",
        };

        return new PxxxxEntities(entityConnectionStringBuilder.ConnectionString);
    }
}

Answer 2

您应该将普通连接字符串传递给DbContext 构造函数，而不是实体连接字符串。所以试着改变你的代码如下：

public ProcessContext()
    : base(ConnectionString())
{
}

private static string ConnectionString()
{
    SqlConnectionStringBuilder sqlBuilder = new SqlConnectionStringBuilder();
    sqlBuilder.DataSource = "XXX";
    sqlBuilder.InitialCatalog = "YYY";
    sqlBuilder.PersistSecurityInfo = true;
    sqlBuilder.IntegratedSecurity = true;
    sqlBuilder.MultipleActiveResultSets = true;

    return sqlBuilder.ToString();
}

Answer 3

你必须改变 Web.config

<connectionStrings>
<add name="DefaultConnection" connectionString="data source=mydb;initial catalog=mydatabase;persist security info=True;user id=sa;password=password;multipleactiveresultsets=True;application name=EntityFramework" providerName="System.Data.SqlClient" />
<add name="DataContext" connectionString="data source=mydb;initial catalog=mydatabase;persist security info=True;user id=sa;password=password;multipleactiveresultsets=True;application name=EntityFramework" providerName="System.Data.SqlClient" />
<!-- Here Add multiple database connection string  -->

在你必须修改 ProcessContext.cs 文件之后 一个创建默认连接的构造函数

public ProcessContext()
      :base("name=DefaultConnection"){
        //here code
       }

其他参数构造函数动态连接数据库

public ProcessContext(string DynamicConnectionString)
       :base(DynamicConnectionString){
// herer code }

这里的默认连接是“DefaultConnection”，但是你有给代码任何控制器的chnage连接字符串

ProcessContext db=new ProcessContext();//this is default connection

ProcessContext db=new ProcessContext("DataContext");//dynamic change connection string 

试试这个代码

Answer 4

这种方法对我很有效。我只是在我的 app.config 中添加了另一个命名连接字符串，然后将名称传递到下面的 GetDbContext() 静态方法中，如下所示。

使用示例：

var dbAlternate = PxxxxEntities.GetDbContext("PxxxxEntitiesAlternate")

将以下内容添加到您的项目中：

public partial class PxxxxEntities
{
    private PxxxxEntities(string name)
        : base("name=" + name)
    {
    }

    public static PxxxxEntities GetDbContext(string name)
    {
        return new PxxxxEntities(name);
    }
}

Answer 5

尝试使用 app.config 文件。然后通过其名称调用所需的连接字符串：

using System.Configuration;

public ProcessContext()
    : base(ConnectionString("foo"))
{
}

private static string ConnectionString(string connKey)
{
    var conn = ConfigurationManager.ConnectionStrings[connKey].ConnectionString;
    return conn;
}

Answer 6

动态连接字符串 EF

使用此代码：

    public Entities(): base(ConnectToSqlServer())
    {
    }



    public static string ConnectToSqlServer()
    {
        SqlConnectionStringBuilder sqlBuilder = new SqlConnectionStringBuilder
        {
            DataSource = "ServerName",
            InitialCatalog = "DatabaseName",
            PersistSecurityInfo = true,
            IntegratedSecurity = false,
            MultipleActiveResultSets = true,

            UserID = "Username",
            Password = "Password",
        };
        var entityConnectionStringBuilder = new EntityConnectionStringBuilder
        {
            Provider = "System.Data.SqlClient",
            ProviderConnectionString = sqlBuilder.ConnectionString,
            Metadata = "res://*/Data.Database.csdl|res://*/Data.Database.ssdl|res://*/Data.Database.msl",
        };

        return entityConnectionStringBuilder.ConnectionString;
    }