从LINQ查询结果集填充DataSet或DataTable

How do you expose a LINQ query as an ASMX web service? Usually, from the business tier, I can return a typed DataSet or DataTable which can be serialized for transport over ASMX.

如何将LINQ查询公开为ASMX Web服务？通常，从业务层，我可以返回一个类型化的DataSet或DataTable，可以序列化以通过ASMX进行传输。

How can I do the same for a LINQ query? Is there a way to populate a typed DataSet or DataTable via a LINQ query?

如何为LINQ查询执行相同操作？有没有办法通过LINQ查询填充类型化的DataSet或DataTable？

public static MyDataTable CallMySproc()
{
    string conn = "...";

    MyDatabaseDataContext db = new MyDatabaseDataContext(conn);
    MyDataTable dt = new MyDataTable();

    // execute a sproc via LINQ
    var query = from dr
                in db.MySproc().AsEnumerable
                select dr;

    // copy LINQ query resultset into a DataTable -this does not work !    
    dt = query.CopyToDataTable();

    return dt;
}

How can I get the result set of a LINQ query into a DataSet or DataTable? Alternatively, is the LINQ query serializeable so that I can expose it as an ASMX web service?

如何将LINQ查询的结果集合并到DataSet或DataTable中？或者，LINQ查询是否可序列化，以便我可以将其作为ASMX Web服务公开？

6 个解决方案

#1

As mentioned in the question, IEnumerable has a CopyToDataTable method:

正如问题中提到的，IEnumerable有一个CopyToDataTable方法：

IEnumerable<DataRow> query =
    from order in orders.AsEnumerable()
    where order.Field<DateTime>("OrderDate") > new DateTime(2001, 8, 1)
    select order;

// Create a table from the query.
DataTable boundTable = query.CopyToDataTable<DataRow>();

Why won't that work for you?

为什么那不适合你呢？

#2

To perform this query against a DataContext class, you'll need to do the following:

要对DataContext类执行此查询，您需要执行以下操作：

MyDataContext db = new MyDataContext();
IEnumerable<DataRow> query = 
    (from order in db.Orders.AsEnumerable()
        select new
        {
            order.Property,
            order.Property2
        })
    as IEnumerable<DataRow>;
return query.CopyToDataTable<DataRow>();

Without the as IEnumerable<DataRow>; you will see the following compilation error:

没有as IEnumerable ;您将看到以下编译错误：

Cannot implicitly convert type 'System.Collections.Generic.IEnumerable' to 'System.Collections.Generic.IEnumerable'. An explicit conversion exists (are you missing a cast?)

无法将类型'System.Collections.Generic.IEnumerable'隐式转换为'System.Collections.Generic.IEnumerable'。存在显式转换（您是否错过了演员？）

#3

Make a set of Data Transfer Objects, a couple of mappers, and return that via the .asmx.
You should never expose the database objects directly, as a change in the procedure schema will propagate to the web service consumer without you noticing it.

制作一组数据传输对象，几个映射器，然后通过.asmx返回。您永远不应该直接公开数据库对象，因为过程模式中的更改将传播到Web服务使用者，而不会注意到它。

#4

If you use a return type of IEnumerable, you can return your query variable directly.

如果使用IEnumerable的返回类型，则可以直接返回查询变量。

#5

Create a class object and return a list(T) of the query.

创建一个类对象并返回查询的列表（T）。

#6

If you use the return type of IEnumerable.It helps return your query variable directly.

如果您使用IEnumerable的返回类型。它有助于直接返回您的查询变量。

MyDataContext db = new MyDataContext();
IEnumerable<DataRow> query = 
    (from order in db.Orders.AsEnumerable()
        select new
        {
            order.Property,
            order.Property2
        })
    as IEnumerable<DataRow>;
return query.CopyToDataTable<DataRow>();

#1