Question 88184 in ASP.NET Question posted in
The official documentation can be found here.

List of elements in a model in .net core – Asp.net

I am trying to understand how models work in .net core and I run into the following problem:
I have a model called blog:

public class Blog
{
    [Key]
    public int Id { get; set; }

    [Required(ErrorMessage = "Title is required")]
    [StringLength(40)]
    public string Title { get; set; }

    [Required(ErrorMessage = "Date is required")]
    [DisplayFormat(ApplyFormatInEditMode = true, DataFormatString = "{0:MM/dd/yyyy}")]
    public DateTime Date { get; set; }

    [Required(ErrorMessage = "Image is required")]
    public string Image { get; set; }

    [Required(ErrorMessage = "Description is required")]
    [StringLength(400)]
    public string Description { get; set; }

    public virtual IList<Paragraph> Paragraphs { get; set; } = new List<Paragraph>();

    [Required(ErrorMessage = "IsActive is required")]
    public bool IsActive { get; set; }

    [Required]
    public int? CompanyId { get; set; }
    public Company Company { get; set; }

    public Blog(){}
}

And the paragraph model:

    [Key]
    public int Id { get; set; }

    [Required(ErrorMessage = "Section is required")]
    public string Section { get; set;}

    [Required]
    public int? BlogId { get; set; }
    public Blog Blog { get; set; }

    public Paragraph()
    {
    }

And when executing the method that should bring me the data from this blog, it returns the list of empty paragraphs

    [HttpGet]
    [Route("api/[controller]/{id}")]
    public IActionResult GetById(int id)
    {
        var findBlog = _db.Blog.Find(id);
        if (findBlog == null)
        {
            return NotFound("Blog not found");
        }
        return new JsonResult(findBlog);
    }

The response:

{
"id": 6,
"title": "Test List",
"date": "2021-10-28T00:00:00",
"image": "https://images.pexels.com/photos/2489/street-building-construction-industry.jpg?auto=compress&cs=tinysrgb&dpr=2&w=500",
"description": "Desc",
"paragraphs": [],
"isActive": true,
"companyId": 1,
"company": null
}
Tags:

2

Answers


  1. 0

    I suppose you are using Entity Framework Core. Then you need to load related data using include function.

    for an example

    using (var context = new BloggingContext())
{
    var blogs = context.Blogs
        .Include(blog => blog.Posts)
        .Include(blog => blog.Owner)
        .ToList();
}

    for your case

     await _dbContext.Blogs
 .Include(blog => blog.Paragraphs)
 .FirstOrDefaultAsync(blog => blog.Id == id);

    And to achieve this, you need to have proper relationships between entities.

    See the SchoolContext here

    Login or Signup to reply.
  2. 0

    You can try to use .Inclue() to include the related data like below:

    using Microsoft.EntityFrameworkCore;

var findBlog = _db.Blog.Include(a => a.Paragraphs).First(a => a.Id == id);
// all these ways can work well
//var findBlog = _db.Blog.Include(a => a.Paragraphs).Where(a => a.Id == id).ToList();
//var findBlog = _db.Blog.Include(a => a.Paragraphs).FirstOrDefault(a => a.Id == id);

    Reference:

    Eager Loading of Related Data

    Login or Signup to reply.
Please signup or login to give your own answer.

Back To Top
Search