刪除Entity Framework中的所有實體

Question

我想使用Entity Framework 4+刪除所有表（所有實體）的內容。如何才能做到這一點？

Answer 1

這將執行很多，比涉及刪除各個實體對象的東西多更好，假設底層數據庫是MSSQL。

foreach (var tableName in listOfTableNames) 
{ 
    context.ExecuteStoreCommand("TRUNCATE TABLE [" + tableName + "]"); 
} 

當然，如果你的表有外鍵關係，你需要設置你的表名的列表以正確的順序，讓你清晰外鍵的表，你明確之前任何主鍵他們可能依賴的表格。

public static void ClearDatabase<T>() where T : DbContext, new() 
    { 
     using (var context = new T()) 
     { 
      var tableNames = context.Database.SqlQuery<string>("SELECT TABLE_NAME FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_TYPE = 'BASE TABLE' AND TABLE_NAME NOT LIKE '%Migration%'").ToList(); 
      foreach (var tableName in tableNames) 
      { 
       context.Database.ExecuteSqlCommand(string.Format("DELETE FROM {0}", tableName)); 
      } 

      context.SaveChanges(); 
     } 
    } 

簡短說明：

Answer 2

迭代通過與代碼像這樣的表：

context.GetType().GetProperties() 
.Where(propertyInfo => propertyInfo.PropertyType == typeof(Table<>)) 
.Select(propertyInfo => propertyInfo.GetValue(context, null) as ITable).ToList() 
.Foreach(table => 
{ 
    //code that deletes the actual tables records. 
} 
); 

Answer 3

只是懶惰的人，尋找答案時的代碼，我想出了自己 我不截斷表由於缺乏權限，如果這不是你的問題，隨時可以這樣做。 where語句忽略表__MigrationHistory。

更新：一些研究，我想出了更好的解決方案（不是很好，但僅刪除所需的列）後：

public static void ClearDatabase(DbContext context) 
    { 
     var objectContext = ((IObjectContextAdapter)context).ObjectContext; 
     var entities = objectContext.MetadataWorkspace.GetEntityContainer(objectContext.DefaultContainerName, DataSpace.CSpace).BaseEntitySets; 
     var method = objectContext.GetType().GetMethods().First(x => x.Name == "CreateObjectSet"); 
     var objectSets = entities.Select(x => method.MakeGenericMethod(Type.GetType(x.ElementType.FullName))).Select(x => x.Invoke(objectContext, null)); 
     var tableNames = objectSets.Select(objectSet => (objectSet.GetType().GetProperty("EntitySet").GetValue(objectSet, null) as EntitySet).Name).ToList(); 

     foreach (var tableName in tableNames) 
     { 
      context.Database.ExecuteSqlCommand(string.Format("DELETE FROM {0}", tableName)); 
     } 

     context.SaveChanges(); 
    } 

Answer 4

截斷不能外鍵內刪除。

然後我做了DbContext的擴展方法。

用法很簡單。

db.Truncates（）; //所有表刪除。

db.Truncates（「Test1」，「Test2」）; //只 「的Test1，Test2的」 表中刪除

public static class DbContextExtension 
{ 
    public static int Truncates(this DbContext db, params string[] tables) 
    { 
     List<string> target = new List<string>(); 
     int result = 0; 

     if (tables == null || tables.Length == 0) 
     { 
      target = db.GetTableList(); 
     } 
     else 
     { 
      target.AddRange(tables); 
     } 

     using (TransactionScope scope = new TransactionScope()) 
     { 
      foreach (var table in target) 
      { 
       result += db.Database.ExecuteSqlCommand(string.Format("DELETE FROM [{0}]", table)); 
       db.Database.ExecuteSqlCommand(string.Format("DBCC CHECKIDENT ([{0}], RESEED, 0)", table)); 
      } 

      scope.Complete(); 
     } 

     return result; 
    } 

    public static List<string> GetTableList(this DbContext db) 
    { 
     var type = db.GetType(); 

     return db.GetType().GetProperties() 
      .Where(x => x.PropertyType.Name == "DbSet`1") 
      .Select(x => x.Name).ToList(); 
    } 
} 

Answer 5

我想設法改善@Wojciech Markowski偉大的答案。

如果你是懶惰和我一樣，不想檢查外鍵約束， 你可以使用這個方法：

 private void ClearDatabase(TContext context) 
    { 
      // disable all foreign keys 
      //context.Database.ExecuteSqlCommand("EXEC sp_MSforeachtable @command1 = 'ALTER TABLE ? NOCHECK CONSTRAINT all'"); 

      List<string> tableNames = context.Database.SqlQuery<string>("SELECT TABLE_NAME FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_TYPE = 'BASE TABLE' AND TABLE_NAME NOT LIKE '%Migration%'").ToList(); 

      for (int i = 0; tableNames.Count>0; i++) 
      { 
       try 
       { 
        context.Database.ExecuteSqlCommand(string.Format("DELETE FROM {0}", tableNames.ElementAt(i % tableNames.Count))); 
        tableNames.RemoveAt(i % tableNames.Count); 
        i = 0; 
       } 
       catch { } // ignore errors as these are expected due to linked foreign key data    
      } 


      context.SaveChanges(); 
    } 

ClearDatabase方法越過表的列表，並清除它們。如果找到FK約束，則捕獲異常並轉到下一個表。 最後所有表格都將被刪除。

而且，如果你不介意失去所有的FK約束，你可以通過行禁用所有的人：

context.Database.ExecuteSqlCommand("EXEC sp_MSforeachtable @command1 = 'ALTER TABLE ? NOCHECK CONSTRAINT all'"); 

還有一件事： 如果你想刪除所有表和未只是清除它們，然後再更換行：

context.Database.ExecuteSqlCommand(string.Format("DELETE FROM {0}", tableNames.ElementAt(i % tableNames.Count))); 

有：

context.Database.ExecuteSqlCommand(string.Format("DROP TABLE {0}", tableNames.ElementAt(i % tableNames.Count))); 

我親自在代碼優先的遷移中在Entity Framework 6上檢查了這個答案。

編輯：更好的版本：

 private void ClearDatabase(MrSaleDbContext context) 
    { 
     //Optional: disable all foreign keys (db-schema will be loosed). 
     //context.Database.ExecuteSqlCommand("EXEC sp_MSforeachtable @command1 = 'ALTER TABLE ? NOCHECK CONSTRAINT all'"); 

     List<string> tableNames = context.Database.SqlQuery<string>("SELECT TABLE_NAME FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_TYPE = 'BASE TABLE' AND TABLE_NAME NOT LIKE '%Migration%' AND TABLE_NAME NOT LIKE 'AspNet%'").ToList(); 

     for (int i = 0; tableNames.Count > 0; i++) 
     { 
      try 
      { 
       //To delete all tables and not just clean them from data, replace "DELETE FROM {0}" in "DROP TABLE {0}": 
       context.Database.ExecuteSqlCommand(string.Format("DELETE FROM {0}", tableNames.ElementAt(i % tableNames.Count))); 
       tableNames.RemoveAt(i % tableNames.Count); 
       i = -1; //flag: a table was removed. in the next iteration i++ will be the 0 index. 
      } 
      catch (System.Data.SqlClient.SqlException e) // ignore errors as these are expected due to linked foreign key data  
      {      
       if ((i % tableNames.Count) == (tableNames.Count - 1)) 
       { 
        //end of tables-list without any success to delete any table, then exit with exception: 
        throw new System.Data.DataException("Unable to clear all relevant tables in database (foriegn key constraint ?). See inner-exception for more details.", e); 
       } 

      } 

     } 

if語句中catch塊檢查自己是否達到了表列表的最後一個索引，而不刪除任何表。在這種情況下，不要進入無限循環，而是拋出異常並退出for。

Answer 6

對於EF 6：

DbSet<Entity>.RemoveRange(DbSet<Entity>);