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Martin Rud 261 posts 1002 karma points c-trib

Apr 18, 2022 @ 09:21

How to loop "inner" array in json

Hi forum,

I am not an expert in C# nor .NET, but I have managed to get looping array data (courses) in external json to work. Now I am stuck in loop some array inside each course (the classes in the course).

Right now I get error "The JSON value could not be converted to MrCourses.ClassesList." in this:

var courses = JsonSerializer.Deserialize<List<Course>>(json);

But if I remove the line:

public ClassesList Classes { get; set; }

in MrCourses.cs the error goes away, but then I get error "'Course' does not contain a definition for 'Classes'..." in view.cshtml:

ClassesList classes = course.Classes;

Below is my code.

MrCourses.cs:

using System.Collections.Generic;

namespace MrCourses
{
    public class CoursesList
    {
        public List<CoursesList> Courses { get; set; }
    }

    public class ClassesList
    {
        public List<CourseClass> MyClasses { get; set; }
    }
    public class Course
    {
        public int Id { get; set; }
        public ClassesList Classes { get; set; }
    }

    public class CourseClass
    {
        public int Id { get; set; }
        public string Name { get; set; }
        public string Address { get; set; }
    }
}

view.cshtml:

@inherits Umbraco.Cms.Web.Common.Views.UmbracoViewPage;
@using System.Net;
@using System.Collections.Generic;
@using System.Text.Json;
@using MrCourses;

@{
    string json = "...";
    var courses = JsonSerializer.Deserialize<List<Course>>(json);
    if(courses.Count != 0) 
    {
        <div>
            @foreach (Course course in courses)
            {
                ClassesList classes = course.Classes;
                <div>
                    <h3>@course.Headline</h3>
                    <p>@course.Abstract</p>
                    @if(ClassesList.Count != 0)
                    {
                        // Loop ClassesList...
                    }

                </div>
            }
        </div>
    }
}

json.json:

[
  {
    "Name": "Course #1",
    "Classes": [
      {
        "Name": "Course #1, class #1",
        "Address": "Course #1, class #1 address"
      },
      {
        "Name": "Course #1, class #1",
        "Address": "Course #1, class #2 address"
      },
      {
        "Name": "Course #1, class #1",
        "Address": "Course #1, class #3 address"
      }
    ]
  },
  {
    "Name": "Course #2",
    "Classes": [
      {
        "Name": "Course #2, class #1",
        "Address": "Course #1, class #1 address"
      },
      {
        "Name": "Course #2, class #1",
        "Address": "Course #1, class #2 address"
      },
      {
        "Name": "Course #2, class #1",
        "Address": "Course #1, class #3 address"
      }
    ]
  }
]

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Paul Seal 524 posts 2889 karma points MVP 7x c-trib

Apr 18, 2022 @ 09:56

0

Hi I’m on my mobile here but I think I’ve spotted something to help. In you if check you are look at ClassesList.Count, I think this should be classes.Count instead.

Paul

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Malthe Petersen 68 posts 383 karma points c-trib

Apr 18, 2022 @ 11:09
100
You should not have that many nested "list" classes.

Do something like this:

var courses = JsonSerializer.Deserialize<List<Course>>(json);

using System.Collections.Generic;

namespace MrCourses { public class Course { public int Id { get; set; } public List
```
public class CourseClass
{
    public int Id { get; set; }
    public string Name { get; set; }
    public string Address { get; set; }
}
```
}

Disclaimer: the code is written on a mobile, sorry for formatting.
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Martin Rud 261 posts 1002 karma points c-trib

Apr 18, 2022 @ 11:54

Thanks, Malthe Petersen! That did the trick. 🙂

Only two classes and "public List

public class Course
    {
        public int Id { get; set; }
        public string Name { get; set; }
        public string Headline { get; set; }
        public string Abstract { get; set; }
        public List<CourseClass> Classes { get; set; }  // Needed to add this line
    }

My view is then:

foreach (var item in course.Classes)
{
    @item.Name
}

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