如何在实体框架中获取表的架构名称

到目前为止，这肯定是一个老话题，但对于那些仍然潜伏在EF6+中的人（如在非EF核心中），基于Rowan Miller在过去的出色博客文章，请检查我的方法，以呈现有关给定实体的一些元信息

public class DbTableMeta
{
    public string Schema { get; set; }
    public string Name { get; set; }
    public IEnumerable<string> Keys { get; set; }
}

public static DbTableMeta Meta(this DbContext context, Type type)
{
    var metadata = ((IObjectContextAdapter) context).ObjectContext.MetadataWorkspace;
    // Get the part of the model that contains info about the actual CLR types
    var items = (ObjectItemCollection) metadata.GetItemCollection(DataSpace.OSpace);
    // Get the entity type from the model that maps to the CLR type
    var entityType = metadata
        .GetItems<EntityType>(DataSpace.OSpace)
        .Single(p => items.GetClrType(p) == type);
    // Get the entity set that uses this entity type
    var entitySet = metadata
        .GetItems<EntityContainer>(DataSpace.CSpace)
        .Single()
        .EntitySets
        .Single(p => p.ElementType.Name == entityType.Name);
    // Find the mapping between conceptual and storage model for this entity set
    var mapping = metadata.GetItems<EntityContainerMapping>(DataSpace.CSSpace)
        .Single()
        .EntitySetMappings
        .Single(p => p.EntitySet == entitySet);
    // Find the storage entity set (table) that the entity is mapped
    var table = mapping
        .EntityTypeMappings.Single()
        .Fragments.Single()
        .StoreEntitySet;
    return new DbTableMeta
    {
        Schema = (string) table.MetadataProperties["Schema"].Value ?? table.Schema,
        Name = (string) table.MetadataProperties["Table"].Value ?? table.Name,
        Keys = entityType.KeyMembers.Select(p => p.Name),
    };
}

DbContext和ObjectContext:的扩展方法

public static class ContextExtensions
{
    public static string GetTableName<T>(this DbContext context) where T : class
    {
        ObjectContext objectContext = ((IObjectContextAdapter) context).ObjectContext;
        return objectContext.GetTableName<T>();
    }
    public static string GetTableName<T>(this ObjectContext context) where T : class
    {
        string sql = context.CreateObjectSet<T>().ToTraceString();
        Regex regex = new Regex("FROM (?<table>.*) AS");
        Match match = regex.Match(sql);
        string table = match.Groups["table"].Value;
        return table;
    }
}

使用ObjectContext对象：

ObjectContext context = ....;
string table = context.GetTableName<Foo>();

使用DbContext对象：

DbContext context = ....;
string table = context.GetTableName<Foo>();

更多信息请点击此处：

实体框架：从实体中获取映射的表名

我发现了以下博客条目，解释了如何从元数据工作区获取这些信息：

https://romiller.com/2014/04/08/ef6-1-mapping-between-types-tables/

以下是神奇的功能：

public static string GetTableName(Type type, DbContext context)
{
    var metadata = ((IObjectContextAdapter)context).ObjectContext.MetadataWorkspace;
    // Get the part of the model that contains info about the actual CLR types
    var objectItemCollection = ((ObjectItemCollection)metadata.GetItemCollection(DataSpace.OSpace));
    // Get the entity type from the model that maps to the CLR type
    var entityType = metadata
            .GetItems<EntityType>(DataSpace.OSpace)
            .Single(e => objectItemCollection.GetClrType(e) == type);
    // Get the entity set that uses this entity type
    var entitySet = metadata
        .GetItems<EntityContainer>(DataSpace.CSpace)
        .Single()
        .EntitySets
        .Single(s => s.ElementType.Name == entityType.Name);
    // Find the mapping between conceptual and storage model for this entity set
    var mapping = metadata.GetItems<EntityContainerMapping>(DataSpace.CSSpace)
            .Single()
            .EntitySetMappings
            .Single(s => s.EntitySet == entitySet);
    // Find the storage entity set (table) that the entity is mapped
    var table = mapping
        .EntityTypeMappings.Single()
        .Fragments.Single()
        .StoreEntitySet;
    // Return the table name from the storage entity set
    return (string)table.MetadataProperties["Table"].Value ?? table.Name;
}

对于那些首先使用代码的人，模式名称是在上下文的OnModelCreating覆盖中设置的；

public static readonly string DefaultSchemaName = "Entities";
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
    modelBuilder.HasDefaultSchema(DefaultSchemaName);
    ...

因此，您应该能够从代码中的其他地方引用DefaultSchemaName。

如果你一开始没有构建模型上下文和EF的东西，这个答案就不那么明显了。

用于截断需要表名和模式的表的示例。

public void ClearTable<T>() where  T: class
    {
        var dbContext = (DbContext) _dbContext;
        
        var annotations = dbContext.Model.FindEntityType(typeof(T)).GetAnnotations().ToList();
        var tableName = annotations.First(c => c.Name == "Relational:TableName").Value.ToString();
        var schema = annotations.First(c => c.Name == "Relational:Schema").Value.ToString();
        dbContext.Database.ExecuteSqlRaw($"truncate table {schema}.{tableName}");
    }

使用实体框架6.1.3，您可以通过以下方式查询方案和表名：

  string tableNameWithScheme = context.Db<T>().Schema+"."+context.Db<T>().TableName;

其中，T是实体的类型，上下文是派生的System.Data.Entity.DBContext.