Discarding "Anonymous" exception while joining tables

Question

I got confused, how to join for example two tables without getting the "Anonymous" exception; for example the following code fraction:

 var result = (from prod in context.ProductsTbls
                              join imag in context.ProductImagesTbls
                              on prod.Id equals imag.ProductId
                              where prod.UserId == 4 && imag.IsDefaultImage == true
                              select new
                              {
                                  Id = prod.Id,
                                  ProductName = prod.ProductName,
                                  ProductDescription = prod.ProductDescription,
                                  ProductCategory = prod.ProductCategory,
                                  ProductPricePerDay = prod.ProductPricePerDay,
                                  ProductPricePerWeek = prod.ProductPricePerWeek,
                                  ProductPricePerMonth = prod.ProductPricePerMonth,
                                  CreationDate = prod.CreationDate,
                                  ModificationDate = prod.ModificationDate,
                                  Image = imag.Image
                              }).ToList();


                IEnumerable<ProductsTbl> data =
 (IEnumerable<ProductsTbl>)result.ToList(); // Exception appears here
                DataTable table = new DataTable();

                using (var reader = ObjectReader.Create(data, "Id", "Image"))
                {
                    table.Load(reader);
                }

After executing the above code, am getting this exception :

System.InvalidCastException: 'Unable to cast object of type 
        'System.Collections.Generic.List`1[<>f__AnonymousType1`10[System.Int32,System.Str
    ing,System.String,System.String,System.Nullable`1[System.Int32],System.Nullable`1
    [System.Int32],System.Nullable`1[System.Int32],System.Nullable`1[System.DateTime]
    ,System.Nullable`1[System.DateTime],System.Byte[]]]' to type 
    'System.Collections.Generic.IEnumerable`1[ClassLibrary1.ProductsTbl]'.'

Pretty much exactly what it says. By using `select new` you're "creating" a new type, that isn't of type `ProductsTbl`. — Evan Trimboli, Jun 12 '18 at 22:32
So don't try to cast to `ProductsTbl`. Why would you? Also, please use the tag [fastmember] for these questions. — Gert Arnold, Jun 12 '18 at 22:33
What is `ObjectReader`? I would imagine the exception is no longer the same. — Evan Trimboli, Jun 12 '18 at 22:51
@EvanTrimboli As I mentioned, I didn't mean that the above could is my current case, it is just an example, my issue about that in most cases I got the anonymous problem. — mustafa mohammed, Jun 12 '18 at 22:58
Which line of code above throws the exception? If it doesn't throw an exception, please show us the code sample that **does**. — mjwills, Jun 12 '18 at 23:26
I reverted your revision because you removed the part that threw the exception, invalidating the whole question. Also marked as duplicate of one of many questions on this topic. — Gert Arnold, Jun 13 '18 at 05:44

score 0 · Accepted Answer · answered Jun 12 '18 at 23:27

In general, when you need the result of a LINQ query to be an IEnumerable or collection of a certain type, you need to create instances of that type in the select.

So, instead of select new { ... } you would use:

select new ProductsTbl {
    // put field values here
}

Discarding "Anonymous" exception while joining tables

1 Answers1