Question
I have a problem with Serialization of Data from database to JSON format. I'm using WebAPI 2 and Entity Framework 6. I've created with EF a Model. The database and the tables with content are even created. When I use the code below I'm getting an error when I type http://localhost:54149/api/qr_group .
Controller:
private EfContext db = new EfContext();
// GET api/<controller>
public IEnumerable<QR_Group> GetGroups()
{
var result = from g in db.QR_Groups
select g;
return result.ToList();
}
I don't know how to use Newtonsoft.Json to serialize the table with the content in JSON format.
I've tried the following code instead of the code above:
public IQueryable<QR_Group> GetGroups()
{
var groupList = (from g in db.QR_Groups
select new
{
name = g.name,
code = g.code
}).AsQueryable();
var json = JsonConvert.SerializeObject(groupList);
return json; //error CS0029: Cannot implicitly convert type `string' to `System.Linq.IQueryable<RestApi.Models.QR_Group>'
}
I get the error CS0029.. How can I solve this to return the data in json? As reminder: The QR_Group entity has 3 columns (Id, name, code)
Popular Answer
Specifically to your second function, JsonConvert.SerializeObject would just serialize any object into a JSON format string, which means you should return a string instead of an IQueryable<>.
So for the controller there are quite a few ways to return it back, like: In MVC, how do I return a string result?
EDIT:
Following code would be one way that should working:
Controller:
private EfContext db = new EfContext();
// GET api/<controller>
public ActionResult GetGroups()
{
var groupList = (from g in db.QR_Groups
select new
{
name = g.name,
code = g.code
}).AsQueryable();
return Content(JsonConvert.SerializeObject(groupList));
}
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