How can I bind a query with a join to a GridView, with a Linq datasource with a business layer and data access layer

问题

I have two tables that I'd like to join together display in a GridView

foo
fooID  fooName barID
1      Alice   2
2      Bob     1
3      Charlie 1

bar
barID  barTitle
1      Developer
2      Project Manager

(relationships and constraints have been defined in the database)

I've got a GridView for foo that outputs like this

Name    Title
Alice   2
Bob     1
Charlie 1

But I'd like see the following

Name    Title
Alice   Project Manager
Bob     Developer
Charlie Developer

Clearly, my SQL would look like:

select fooName as Name, barTitle as Title
from foo join bar on foo.barid = bar.barid

Buried deep in my code I have the following:

FooDAL.cs

// ...
namespace ourDAL{
// ...
public class fooDAL : ICRUD <foo>, IDisposable //ICRUD is just an interface
{
// ...
  ourPoco context; // ourPoco was auto generated by a template from our  
                   // database and an EDMX file.

  public fooDAL()
  {
      context = new ourPoco;
  }
// ...
    public IList<Cfoo> FindAll()
    {
        return (from c in context.foo
                select c).ToList<foo>();
    }
// ...

I think in here I should be able to construct a Join in Linq, but I'm not sure how to do that. How can I mod the Linq code to handle the join?

回答1:

You can use this query:

select  a.fooName as Name, b.barTitle as Title from foo a inner join bar b
on a.barid= b.barid

also in your grid you need to change from

<asp:BoundField DataField="BarID" HeaderText="Title" />

<asp:BoundField DataField="Title" HeaderText="Title" />

The equivalent LINQ query would be:

var a = (from p in foo 
            join q in bar 
            on p.barid equals q.barid 
            select new { Name= p.fooName , Title = q.barTitle }).ToList();

来源：https://stackoverflow.com/questions/15150363/how-can-i-bind-a-query-with-a-join-to-a-gridview-with-a-linq-datasource-with-a

标签

ASP.NET

linq

gridview