How to custom response in asp.net web api2

Question

the problem in this function when add this two lines.

UserImage = GetImagePath(db.Users.FirstOrDefault(x => x.Id == p.User_ID).Image),  
InsertDate = p.InsertDate.ToString("dd/MM/yyyy")

I need to custom Image Path and custom date format,show this problem.
LINQ to Entities does not recognize the method System.String ToString(System.String) method, and this method cannot be translated into a store expression

private static string GetImagePath(string ImageName)
{
    return System.Configuration.ConfigurationManager.AppSettings["websiteurl"].ToString() + "/uploads/" + ImageName;
}

[HttpGet]
[Route("Comments")]
public IHttpActionResult Comments(string Post_ID)
{
    var list = db
        .ShalehComments
        .Where(p => p.Shaleh_ID == Post_ID && p.ParentID == 0)
        .Select(p => new {
            ID = p.ID,
            Comment = p.Comment,
            User = db.Users.FirstOrDefault(x=> x.Id == p.User_ID).FullName,
            UserImage = GetImagePath(db.Users.FirstOrDefault(x => x.Id == p.User_ID).Image),//here problem
            InsertDate = p.InsertDate.ToString("dd/MM/yyyy")//and here
    }).ToList();

    return Ok(
        new
        {
            result = true,
            data = list
        }
    );
}

Ashiquzzaman · Accepted Answer · 2017-06-01 07:11:47Z

1

This error occurred because Entity Framework does not know how to execute .ToString() or GetImagePath method in sql. So you should load the data by using ToList.So you try something like:

[HttpGet]
[Route("Comments")]
public IHttpActionResult Comments(string Post_ID)
{
    var list = db
        .ShalehComments
        .Where(p => p.Shaleh_ID == Post_ID && p.ParentID == 0)
        .ToList()//add ToList
        .Select(p => new {
            ID = p.ID,
            Comment = p.Comment,
            User = db.Users.FirstOrDefault(x=> x.Id == p.User_ID).FullName,
            UserImage = GetImagePath(db.Users.FirstOrDefault(x => x.Id == p.User_ID).Image),
            InsertDate = p.InsertDate.ToString("dd/MM/yyyy")//and here
    }).ToList();

    return Ok(
        new
        {
            result = true,
            data = list
        }
    );
}

edited Jun 1, 2017 at 7:11

answered Jun 1, 2017 at 6:02

Ashiquzzaman

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4 Comments

Web Developer Over a year ago

But this method is expensive in performance. Are there other better ways?

Ashiquzzaman Over a year ago

another way you can do all conversion into SQL Query. but in EF when you execute sql query it return IEnumerable but it's expensive too. so i thing it better.

Phil Cooper Over a year ago

@WebDeveloper a stored procedure?

Ashiquzzaman Over a year ago

@PhilCooper If you use EF then same result as Raw Query .you get the result as IEnumerable

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