WebAPI JSON Serialize Entity Framework

Question

In my WebAPI, I'm using EF. I'm currently getting my data out using a LINQ statement.

My LINQ is:

var output = _context.CarMakes
.Select(x => new 
{
 id= x.CarId,
 make = x.CarMake,
 year = x.Year,
 status = x.Status 
});

my data is returned as:

[
 { 
 "id": 1,
 "make": "Ford",
 "year" : 2020,
 "model" : "Focus"
 },
 {
 "id" : 2,
 "make" :"Ford",
 "year" : 1994,
 "model" : "F-150"
 },
 {
 "id" : 3,
 "make" : "Chevy",
 "year" : 2022,
 "model" : "Silverado"
 
 }
 ]
 

How can I get it returned so it's grouped so I can use it in a TreeView navigation menu such as: What changes should I make to the .NET code?

 Ford:
 2020
 Focus
 1994
 F-150
 Chevy
 2022
 Silverado
 
 

• ShubhamWagh: make is twice in your JSON.

Answer 1

you need to use group by to get the result needed, here is an example :

var result = _context.CarMakes.GroupBy(x => x.make)
 .Select(g => new {
 Make = g.Key,
 Models = g.GroupBy(x => x.year)
 .Select(y => new {
 Year = y.Key,
 Name = y.Select(z => z.model)
 })
 });

• JustWantsToCode: This is what I'm looking for, thanks, I need to add the ID field to this as well so when the user clicks on the mdoel, It'll take them to the details for that model, Is there a way to add the ID field for the model and still have it grouped as such?

Answer 2

You have to perform group by on make and year fields and then select all the cars that come under those grouping. Then in the front end, you can use this returned data to make a nested tree view.

var output = _context.CarMakes
 .Select(x => new
 {
 id = x.CarId,
 make = x.CarMake,
 year = x.Year,
 status = x.Status
 })
 .GroupBy(x => new { x.make, x.year })
 .Select(g => new
 {
 make = g.Key.make,
 year = g.Key.year,
 cars = g.Select(x => new { id = x.id, status = x.status })
 });