Problem with using a ToExpando method

Question

Hi I i try to use a ToExpando solution to use anonymous classes in razor views. I use this solution -> Dynamic Anonymous type in Razor causes RuntimeBinderException

I'll write what i did:

I added a file Extensions.cs where i put following code:

public static class Extensions
{
    public static ExpandoObject ToExpando(this object anonymousObject)
    {
        IDictionary<string, object> anonymousDictionary = HtmlHelper.AnonymousObjectToHtmlAttributes(anonymousObject);
        IDictionary<string, object> expando = new ExpandoObject();
        foreach (var item in anonymousDictionary)
            expando.Add(item);
        return (ExpandoObject)expando;
    }
}

I wrote a query that receive a tuples from database in controller method:

IEnumerable<dynamic> articles = (from p in db.Articles.Where(p => p.user_id == 2)
        select new
        {
            p.article_id,
            p.title,
            p.date,
            p.category,
            AverageScore = db.Articles_Scores
                .Where(o => o.user_id == p.user_id && p.article_id == o.article_id)
                .Average(m => m.score)
        }).AsEnumerable()
          .Select(r => r.ToExpando());
int ii = 0;
foreach(var it in articles) {
    // HERE I CAN READ EVERYTHING
    ii = it.article_id;
}
return View(articles);

In view I declare a model:
```
@model IEnumerable<dynamic>
```

And I try to get every tuples:

@foreach (dynamic item in Model) {
// some code
    @item.article_id // HERE IS EXCEPTION
}

In the foreach line I got an Exception:

RuntimeBinderException: 'System.Dynamic.ExpandoObject' does not contain a definition for 'article_id'

What did I do wrong?

You've haven't shown is the code that actually calls `ToExpando`. — vcsjones, Jul 12 '11 at 16:02

score 5 · Answer 1 · answered Jul 12 '11 at 16:01

5

You need to call .AsEnumerable() or .ToList() first to force ToExpando to run on the client.

answered Jul 12 '11 at 16:01

SLaks

868,454
176
1,908
1,964

Do you mean I should use ToExpando().AsEnumerable()? If so, I gave an similar exception :/ – nosbor Jul 12 '11 at 16:54
1

No; you need to call `AsEnumerable` _first_ so that `ToExpando` runs on the client – SLaks Jul 12 '11 at 16:55
Ok. But I got an Exception: RuntimeBinderException: 'System.Dynamic.ExpandoObject' does not contain a definition for 'article_id' – nosbor Jul 12 '11 at 19:39

Matthew Abbott · Answer 2 · 2011-07-14T15:54:33.877

3

Try:

dynamic articles = (from p in db.Articles.Where(p => p.user_id == 2_
                select new
                {
                    p.article_id,
                    p.title,
                    p.date,
                    p.category,
                    AverageScore = db.Articles_Scores
                        .Where(o => o.user_id == p.user_id && p.article_id == o.article_id)
                        .Average(m => m.score)
                }).AsEnumerable()
                  .Select(r => r.ToExpando());

Edit: Make sure you declare dynamic not var

Edit 2: In your for look, you're declaring var again. Change it to:

@foreach (dynamic item in Model) {
    // some code
    @item.article_id // HERE IS EXCEPTION
}

edited Jul 14 '11 at 15:54

answered Jul 12 '11 at 16:48

Matthew Abbott

60,571
9
104
129

I got an Exception: RuntimeBinderException: 'System.Dynamic.ExpandoObject' does not contain a definition for 'article_id' – nosbor Jul 13 '11 at 18:42
Thanks for help Matthew but it still doesnt work. I used IEnumerable and now I used your solution but still there is the same problem. It is strange... because it works perfect in controler method(foreach works great and I can read every properties) but in View(Razor) I got the same exception. I really dont know what i'm doing wrong... – nosbor Jul 14 '11 at 15:21
I updated my post. Look at code below linq query. I also checked by comment a place where I got exception. – nosbor Jul 14 '11 at 15:52
What worked for me is doing this ... (from ... (select new {}).ToExpando()).ToList(). Basically, making sure the expando was on the actual object created, not after. Doing it the other way (With a new select) will also work, and may actually be cleaner looking. – Andrew Sep 19 '11 at 07:18
Edit 1 is very important as the objects are created there. In my case Edit 2 was not required i.e. @foreach (var item in Model) worked perfectly – BiLaL Sep 08 '15 at 09:12

score 1 · Answer 3 · answered Sep 19 '11 at 07:34

Ok, building on the first two answers, I added another extension method that I'm surprised I don't see here:

public static List<ExpandoObject> ToExpandoList<T>(this IEnumerable<T> ie) {
    return ie.Select(o => o.ToExpando()).ToList();            
}

And now in my view I have code like this, and it works just fine using Razor.

var peoples = from f in "tom dick susan roberto".Split(' ') 
              select new { FirstName = f, Age = f.Length };
ViewBag.People = peoples.ToExpandoList();

linq.ToExpando().ToList() did not worked for me but your helper of .ToExpandoList() is successful. — BiLaL, Sep 08 '15 at 09:10

score 0 · Answer 4 · answered Jul 19 '11 at 13:24

0

The problem is HtmlHelper.AnonymousObjectToHtmlAttributes(), it's replacing '_' with '-' for the property name. Look at the comment for the method.

answered Jul 19 '11 at 13:24

Sperling

171
5

Problem with using a ToExpando method

4 Answers4

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