插入带有Dapper错误的IEnumerable 集合，“Dapper不支持类”。
是的， 这里和这里有关于如何使用dapper-dot-net插入记录的问题 。 然而，答案虽然提供了丰富的信息，但似乎并未将我指向正确的方向。 以下是这种情况：将数据从SqlServer移动到MySql。 将记录读入IEnumerable很容易，但我只是没有在插入上获取内容。 首先，’移动记录代码’：
// moving data Dim session As New Session(DataProvider.MSSql, "server", _ "database") Dim resources As List(Of WTUser) = session.QueryReader(Of WTUser)("select * from tbl_resource") session = New Session(DataProvider.MySql, "server", "database", _ "user", "p@$$w0rd") // *edit* - corrected parameter notation with '@' Dim strInsert = "INSERT INTO tbl_resource (ResourceName, ResourceRate, ResourceTypeID, ActiveYN) " & _ "VALUES (@ResourceName, @ResourceRate, @ResourceType, @ActiveYN)" Dim recordCount = session.WriteData(Of WTUser)(strInsert, resources) // session Methods Public Function QueryReader(Of TEntity As {Class, New})(ByVal Command As String) _ As IEnumerable(Of TEntity) Dim list As IEnumerable(Of TEntity) Dim cnn As IDbConnection = dataAgent.NewConnection list = cnn.Query(Of TEntity)(Command, Nothing, Nothing, True, 0, CommandType.Text).ToList() Return list End Function Public Function WriteData(Of TEntity As {Class, New})(ByVal Command As String, ByVal Entities As IEnumerable(Of TEntity)) _ As Integer Dim cnn As IDbConnection = dataAgent.NewConnection // *edit* if I do this I get the correct properties, but no data inserted //Return cnn.Execute(Command, New TEntity(), Nothing, 15, CommandType.Text) // original Return statement Return cnn.Execute(Command, Entities, Nothing, 15, CommandType.Text) End Function
cnn.Query和cnn.Execute调用dapper扩展方法。 现在，WTUser类（注意：列名在SqlServer中从’WindowsName’更改为MySql中的’ResourceName’，因此两个属性指向同一个字段）：
Public Class WTUser // edited for brevity - assume the following all have public get/set methods Public ActiveYN As String Public ResourceID As Integer Public ResourceRate As Integer Public ResourceType As Integer Public WindowsName As String Public ResourceName As String End Class
我从dapper收到一个例外：“Dapper不支持WTUser。” DataMapper（dapper）中的这个方法：
private static Action CreateParamInfoGenerator(Type OwnerType) { string dmName = string.Format("ParamInfo{0}", Guid.NewGuid()); Type[] objTypes = new[] { typeof(IDbCommand), typeof(object) }; var dm = new DynamicMethod(dmName, null, objTypes, OwnerType, true); // < p.Name))
此时OwnerType =
System.Collections.Generic.List`1 [[CRMBackEnd.WTUser，CRMBE，Version = 1.0.0.0，Culture = neutral，PublicKeyToken = null]]，mscorlib，Version = 2.0.0.0，Culture = neutral，PublicKeyToken = b77a5c561934e089
似乎OwnerType应该是CRMBackEnd.WTUser …不是List …… ??? 因为正在发生的事情是集合属性正在被迭代：Count，Capacity等。我缺少什么？
更新
如果我将session.WriteData修改为：
Public Function WriteData(Of TEntity As {Class, New})(ByVal Command As String, _ ByVal Entities As IEnumerable(Of TEntity)) _ As Integer Dim cnn As IDbConnection = dataAgent.NewConnection Dim records As Integer For Each entity As TEntity In Entities records += cnn.Execute(Command, entity, Nothing, 15, CommandType.Text) Next Return records End Function
记录被很好地插入…但我不认为这是必要的，例如：
connection.Execute(@"insert MyTable(colA, colB) values (@a, @b)", new[] { new { a=1, b=1 }, new { a=2, b=2 }, new { a=3, b=3 } } ).IsEqualTo(3); // 3 rows inserted: "1,1", "2,2" and "3,3"
……来自dapper-dot-net
我刚刚为此添加了一个测试：
class Student { public string Name {get; set;} public int Age { get; set; } } public void TestExecuteMultipleCommandStrongType() { connection.Execute("create table #t(Name nvarchar(max), Age int)"); int tally = connection.Execute(@"insert #t (Name,Age) values(@Name, @Age)", new List { new Student{Age = 1, Name = "sam"}, new Student{Age = 2, Name = "bob"} }); int sum = connection.Query("select sum(Age) from #t drop table #t").First(); tally.IsEqualTo(2); sum.IsEqualTo(3); }
它像宣传的那样工作。 我对multi-exec的工作方式做了一些修改（所以它的速度更快，支持object []）。
我的猜测是你有问题，因为你在WTUser所有领域都缺少一个getter属性。 所有参数都必须具有阅读器属性，我们不支持从字段中提取它，它需要复杂的解析步骤才能保持高效。
导致问题的另一个问题是将dapper传递给不支持映射的param。
例如，以下类不支持作为参数：
class Test { public int Id { get; set; } public User User {get; set;} } cnn.Query("select * from Tests where Id = @Id", new Test{Id = 1}); // used to go boom
问题是dapper没有解析SQL，它假设所有的道具都可以设置为params但是无法解析User的SQL类型。
最新转速解决了这个问题