带有 Ienumerable 的 Asp.net mvc 返回模型

Question

I am having a problem of the return type IEnumerable<> of the model which I try to better understand:

I am having a Model view:

public class Photoview
{
    public int IdPhoto { get; set; }
    public DateTime Date { get; set; }
    public string Nom { get; set; }
    public int Category { get; set; }
    public string Lien { get; set; }
    public bool Actif { get; set; }
    public string Description { get; set; }
}

and a model, which gets data from the database:

    public IEnumerable<Photoview> GetAllPhotos()
    {
        var a = from o in _ajAentities.Photos
                select o;

        return a.ToList();
    }

However, I am having a compile error :cannot convert type Generic.List to

The table of the database is:

id_photo    int         Unchecked
date    smalldatetime   Checked
nom         nvarchar(250)   Checked
categorie   int         Checked
lien    nvarchar(250)   Checked
actif   bit         Checked
description nvarchar(800)   Checked

My question is: How would I make it possible to return the Linq query of GetAllPhotos() as IEnumerable<> type ?

Thanks

Answer 1

It seems that the _ajAentities.Photos is of type IEnumerable<Models.DB.Photo> and yet you are trying to return an IEnumerable<Photoview> from your method.

So the first possibility is to fix your return type to match that of your database entity:

public IEnumerable<Photo> GetAllPhotos()
{
    var a = 
        from o in _ajAentities.Photos
        select o;
    return a.ToList();
}

The second possibility is to map between the two types:

public IEnumerable<Photoview> GetAllPhotos()
{
    var a = 
        from o in _ajAentities.Photos
        select new Photoview
        {
            IdPhoto = o.Id,
            Date = o.Date,
            Nom = o.Nom,
            ....
        };

    return a.ToList();
}

You might also take a look at AutoMapper to perform the mapping between your domain models and your view models.

Answer 2

Try this:

var a = (IEnumerable<Object>)
        from o in _ajAentities.Photos
        select o;

It casts the IQueriable to IEnumerable returned from Linq. Do no use the .ToList() because you're converting it to List type collection. Just return the variable.