Error: An expression tree may not contain a dynamic operation

Question

I use Asp.Net 4 and C#, I use EF 4.

I have this query, I receive an error:

 An expression tree may not contain a dynamic operation

dynamic o = e.Item.DataItem;
var imagesContent = context.CmsImagesContents.FirstOrDefault(img => img.ContentId == o.ContentId);

It seems is imposible to Cast a Dynamic Type using a Lamba Expression.

How I can fix the problem, and able to use my object o in my Lamba? Thanks

PS: e.Item.DataItem is of Type CmsContent and o.ContentId is of type Int

Can you cast `e.Item.DataItem` to the type that defines the `ContentId` property? — cdhowie, Aug 19 '11 at 07:58
I'm not able to do it inside the Lamba. Any idea how to make it? — GibboK, Aug 19 '11 at 08:00
`var o = (SomeType)e.Item.DataItem;` where `SomeType` is the type of object you are expecting. — cdhowie, Aug 19 '11 at 08:02
You need to show us why you *have to* declare `o` as `dynamic` first. — Cheng Chen, Aug 19 '11 at 08:04
duplicate of http://stackoverflow.com/questions/5614574/an-expression-tree-may-not-contain-a-dynamic-operation/14466282 -- better answer there — drzaus, Jan 22 '13 at 19:20

score 15 · Accepted Answer · edited Sep 24 '18 at 18:26

15

Unboxing the object will do the trick:

     int contentId = (int)o.ContentId;
     var image = context.CmsImagesContents.FirstOrDefault(img => img.ContentId == contentId);

For more info about 'boxing/unboxing' click here

edited Sep 24 '18 at 18:26

Jeric Cruz

answered Aug 19 '11 at 08:13

GibboK

score 4 · Answer 2 · answered Aug 19 '11 at 08:04

4

Change

dynamic o = e.Item.DataItem;

To

var o = (CmsContent)e.Item.DataItem;

answered Aug 19 '11 at 08:04

cdhowie

2 Answers2