如何在EntityDataSource中添加子表的计数 [英] How to add Count of child table in EntityDataSource

问题描述

我有一个EntityDataSource，用于从tblOrderFile获取行数据，如下所示：

I have an EntityDataSource that works to get row data from tblOrderFile as follows:

<asp:EntityDataSource ID="entityDataSourcePreorder" runat="server" 
        ConnectionString="name=iDBEntities" 
        DefaultContainerName="iDBEntities" EnableFlattening="False" 
        EntitySetName="tblOrderFiles" 
        Select="it.[pkOrderFileID], it.[fkOrderFileStatusID], it.[Filename], it.[CreateDate], it.[UserId]" 
        AutoGenerateWhereClause="True" EntityTypeFilter="" Where="">

我现在想修改它也返回子表中的行数tblOrderFileItem实体集名称tblOrderFileItems）。

I would now like to modify it to also return back the number of rows in child table tblOrderFileItem (with Entity Set Name tblOrderFileItems).

我发现通过添加一个Include指令来使Count工作的方法如下：

I found a way to get the Count to work by adding an Include directive as follows:

    <asp:EntityDataSource ID="entityDataSourcePreorder" runat="server" 
        ConnectionString="name=iDBEntities" 
        DefaultContainerName="iDBEntities" EnableFlattening="False" 
        EntitySetName="tblOrderFiles" Include="tblOrderFileItems"
        AutoGenerateWhereClause="True" EntityTypeFilter="" Where="" >
    </asp:EntityDataSource>

但我相信这是返回每个订单项的所有行的所有列。我只是真的想要Count，不想将其余的数据传递到网页。

but I believe this is returning the all the columns of all the rows for each Order Item. I only really want the Count and do not want to deliver the rest of the data to the web page.

我也试过简单地添加it.tblOrderFileItems.Count到Select语句，但得到错误说

I also tried simply adding it.tblOrderFileItems.Count to the Select statement but get an error saying

'Count'不是'Transient.collection [MyDBModel.tblOrderFileItem（Nullable = True，DefaultValue =）]'。要提取集合元素的属性，请使用子查询对集合进行迭代。

'Count' is not a member of 'Transient.collection[MyDBModel.tblOrderFileItem(Nullable=True,DefaultValue=)]'. To extract a property of a collection element, use a subquery to iterate over the collection.

推荐答案

Select="ANYELEMENT(SELECT VALUE Count(c.ItemId) FROM it.tblOrderFileItems AS c) as ChildCount"

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