Question

问题

简单地说，映射没有按预期执行。局部变量reason返回null，因此对nav的赋值也将嵌套对象Reason设置为null。

我在这里错过了一些简单的东西吗？

存储过程

ALTER PROCEDURE [PA].[spGetDocumentNavById]
-- Add the parameters for the stored procedure here
@DocumentNavID INT
AS
BEGIN
-- SET NOCOUNT ON added to prevent extra result sets from
-- interfering with SELECT statements.
SET NOCOUNT ON;

-- Insert statements for procedure here
SELECT
    dn.DocumentNavID,
    dn.IssuerName,
    nt.Name,
    dn.Amount,
    dn.BTF,
    dn.NavDate,
    dn.ReceivedDate,
    dn.PrimaryIdentifier,
    dn.AssetID,
    dh.LastModifiedBy,
    dh.IsApproved,
    dh.Corrected,
    dh.ReasonID
FROM PA.DocumentNavs dn WITH(NOLOCK)
    JOIN PA.NAVTypes nt WITH(NOLOCK)
        ON nt.NAVTypeID = dn.NavTypeID
    LEFT JOIN PA.DocumentsHistory dh WITH(NOLOCK)
        ON dh.DocumentID = dn.DocumentID
    LEFT JOIN PA.Analysts a WITH(NOLOCK)
        ON a.AnalystID = dh.LastModifiedBy
WHERE dn.DocumentNavID = @DocumentNavID

C＃

public DocumentNav FindById(int documentNavId)
    {
        var data = new
        {
            documentNavId
        };

        using (var conn = SqlConnection)
        {
            var response = conn.Query<DocumentNav, Reason, DocumentNav>("[PA].spGetDocumentNavById",
                map: (nav, reason) =>
                {
                    nav.Reason = reason;
                    return nav;
                }, param: data, splitOn: "ReasonID", commandType: System.Data.CommandType.StoredProcedure)
                .DefaultIfEmpty().FirstOrDefault();

            return response;
        }
    }

Answer 1

Dapper能够按Id列（“Id”或“id”）拆分返回的行查询。如果您的主键不同或者您希望将行拆分为Id以外的其他位置，请使用可选的“splitOn”参数。
在您的示例中，查询应如下所示：

SELECT
    -- DocumentNav Object Columns 
    dn.DocumentNavID AS "Id",
    dn.IssuerName,
    -- ... all other DocumentNav properties..
    -- Reason Object Columns
    dh.ReasonID AS "Id"
    dh.LastModifiedBy,
    dh.IsApproved,
    dh.Corrected
    -- ... all other Reason properties..
FROM PA.DocumentNavs dn WITH(NOLOCK)
    JOIN PA.NAVTypes nt WITH(NOLOCK)
        ON nt.NAVTypeID = dn.NavTypeID
    LEFT JOIN PA.DocumentsHistory dh WITH(NOLOCK)
        ON dh.DocumentID = dn.DocumentID
    LEFT JOIN PA.Analysts a WITH(NOLOCK)
        ON a.AnalystID = dh.LastModifiedBy
WHERE dn.DocumentNavID = @DocumentNavID

您需要使用属性名称“Id”（DocumentNav＆amp; Reason）

使用Dapper映射到无效的嵌套对象

1 个答案: