Cannot Convert From List to List

Question

I have a IRepository and Repository that take in an anonymous type but it throws an error that it can't convert from List<T> to List<T>. The only reason I could think that this would happen is maybe T from IRepository and T from Repository is ambiguous.

public interface IRepository<T> where T : class
{
    void DeserializeJSON<T>();
    ...
}

public class Repository<T> : IRepository<T> where T : class
{
    private string data;
    private List<T> entities;

    public void DeserializeJSON<T>()
    {
                   // Cannot implicitly convert type
        entities = JsonConvert.DeserializeObject<List<T>>(data);
    }
    ...
}

possible duplicate of [How to deserialize using JSON.Net to an anonymous type?](http://stackoverflow.com/questions/7995856/how-to-deserialize-using-json-net-to-an-anonymous-type) — Ian Mercer, Nov 22 '13 at 03:28

iamkrillin · Accepted Answer · 2013-11-22T03:38:43.857

2

change your defintions to be like so..

public interface IRepository<T> where T : class
{
    void DeserializeJSON();
}

public class Repository<T> : IRepository<T> where T : class
{
    private string data;
    private List<T> entities;

    public void DeserializeJSON()
    {
                   // Cannot implicitly convert type
        entities = JsonConvert.DeserializeObject<List<T>>(data);
    }
}

When you template the class, you don't need to template the functions. If you do the compiler believes they are of different types even though you are using the same variable

edited Nov 22 '13 at 03:38

answered Nov 22 '13 at 03:10

iamkrillin

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"Cannot implicitly convert from List to List" – Bacon Nov 22 '13 at 03:14
Thanks for the feedback. This is an error in the early stages. I have yet to try and instantiate a repository because I'm getting this error while coding the repository. – Bacon Nov 22 '13 at 03:26
1

acutually the problem is with how you are declaring your generic class.. I am about to update my answer – iamkrillin Nov 22 '13 at 03:30
1

Moral of a fable: Never turn off Warnings ! – thepirat000 Nov 22 '13 at 03:33
@iamkrillin Fantastic! That worked liked a charm. Thanks a bunch. – Bacon Nov 22 '13 at 03:40

score 1 · Answer 2 · answered Nov 22 '13 at 03:37

The problem was due to wrong declaration. The class uses T as template type, and the method uses another T, which 2 things is absolutely different.

To resolve your problem, please remove T template declaration on your method.

public void DeserializeJSON()

Instead of

public void DeserializeJSON<T>()

Cannot Convert From List to List

2 Answers2