EF Core related entities only returns one record in a one-to-many relationship

Question

EF Core related entities only returns one record in a one-to-many relationship

Espi 1

I have an app that lists Computers in a domain. Each computer has a one-to-many relationship to an Applications table. I am able to pull the Computer details, but when I map try to pull the Applications associated with the computer I only get one returned. Here is my setup:

Models

Public class computers  
  
        [Key]  
            public int computerid { get; set; }  
            public ICollection<applications> applications { get; set; }  
            public ICollection<hotfixes> hotfixes { get; set; }  
      
    Public class applications  
            [ForeignKey ("computerid")]  
            public computers computers { get; set; }  
      
    Public class hotfixes  
            [ForeignKey ("computerid")]  
            public computers computers { get; set; }  
  
**Details.cshtml.cs**  
         public computers computers { get; set; }  
  
         public async Task<IActionResult> OnGetAsync(int? id)  
         {  
            if (id == null)  
            {  
                return NotFound();  
            }  
  
            computers = await _context.Computers  
                        .Include(a => a.applications)  
                        .Include(h => h.hotfixes)  
                        .AsNoTracking()  
                        .AsSingleQuery()  
                        .FirstOrDefaultAsync(m => m.id == id);  
  
           if (computers == null)  
           {  
               return NotFound();  
           }  
               return Page();  
  
        }  
  
  
**Details.cshtml**  
  
section calling the related applications records - ONLY ONE APPLICATION RECORD IS RETURNED  
  
 @foreach (var application in Model.computers.applications)  
                      
            {  
             <tr>  
              <td width="25%" align="center">@Html.DisplayFor(modelapplication => application.name)</td>  
              <td width="25%" align="center">@Html.DisplayFor(modelapplication => application.version)</td>  
              <td width="25%" align="center">@Html.DisplayFor(modelapplication => application.publisher)</td>  
              <td width="25%" align="center">@Html.DisplayFor(modelapplication => application.installdate)</td>  
              </tr>    
             }  
  
  
section calling the related hotfixes records - ONLY ONE HOTIX RECORD IS RETURNED  
  
@foreach (var hotfix in Model.computers.hotfixes)  
              {  
               <tr>  
               <td width="20%" align="center">@Html.DisplayFor(modelItem => hotfix.name)</td>  
                <td width="20%" align="center">@Html.DisplayFor(modelItem => hotfix.helplink)</td>  
                <td width="20%" align="center">@Html.DisplayFor(modelItem => hotfix.description)</td>  
                <td width="20%" align="center">@Html.DisplayFor(modelItem => hotfix.installedon)</td>  
                <td width="20%" align="center">@Html.DisplayFor(modelItem => hotfix.installedby)</td>  
                </tr>  
               }

I cannot seem to be able to make it work no matter what I do. Any guidance would be appreciated.

Daniel Zhang-MSFT 9,646 Reputation points

2021-06-03T09:12:40.86+00:00

Hi @Espi ,
First, no foreign key named "computerid" was found in your applications and hotfixes classes.
If you are using shadow foreign key, how did you configure it? Please provide more code for configuring one-to-many relationship.
I suggest you can refer to this document.
Best Regards,
Daniel Zhang

Espi 1

Hi @Daniel Zhang-MSFT ,

All 3 model classes (computers, applications, hotfixes) have a "computerid" field.

In the computers class, it is set as Key

Public class computers              
            [Key]  
            public int computerid { get; set; }  
            public ICollection<hg_applications> applications { get; set; }  
            public ICollection<hg_hotfixes> hotfixes { get; set; }

In the applications & hotfixes it it is set as a foreign key

 Public class applications   
           public int computerid { get; set; }  
            [ForeignKey("computerid")]  
            public computers computers { get; set; }  
      
    Public class hotfixes  
            public int computerid { get; set; }  
            [ForeignKey("computerid")]  
            public computers computers { get; set; }

Espi 1

This is the Fluent API setting

modelBuilder.Entity<computers>()
                .HasMany(a => a.applications)
                .WithOne(c => c.computers);

modelBuilder.Entity<computers>()
                .HasMany(h => h.hotfixes)
                .WithOne(c => c.computers);

Daniel Zhang-MSFT 9,646 Reputation points

2021-06-04T06:34:11.51+00:00
Hi Espi-7557,
Please change your following codes

public ICollection<hg_applications> applications { get; set; } public ICollection<hg_hotfixes> hotfixes { get; set; }

to

public ICollection<applications> applications { get; set; } public ICollection<hotfixes> hotfixes { get; set; }

And you can also try to use List<> instead of ICollection<> .
Best Regards,
Daniel Zhang

Your answer

Daniel Zhang-MSFT 9,646 Reputation points

2021-06-03T09:12:40.86+00:00

Hi @Espi ,
First, no foreign key named "computerid" was found in your applications and hotfixes classes.
If you are using shadow foreign key, how did you configure it? Please provide more code for configuring one-to-many relationship.
I suggest you can refer to this document.
Best Regards,
Daniel Zhang
Espi 1 Reputation point

2021-06-03T16:21:29.643+00:00

Hi @Daniel Zhang-MSFT ,

All 3 model classes (computers, applications, hotfixes) have a "computerid" field.

In the computers class, it is set as Key

Public class computers [Key] public int computerid { get; set; } public ICollection<hg_applications> applications { get; set; } public ICollection<hg_hotfixes> hotfixes { get; set; }

In the applications & hotfixes it it is set as a foreign key

Public class applications public int computerid { get; set; } [ForeignKey("computerid")] public computers computers { get; set; } Public class hotfixes public int computerid { get; set; } [ForeignKey("computerid")] public computers computers { get; set; }
Espi 1 Reputation point

2021-06-03T20:31:50.563+00:00

This is the Fluent API setting

modelBuilder.Entity<computers>() .HasMany(a => a.applications) .WithOne(c => c.computers); modelBuilder.Entity<computers>() .HasMany(h => h.hotfixes) .WithOne(c => c.computers);
Daniel Zhang-MSFT 9,646 Reputation points

2021-06-04T06:34:11.51+00:00

Hi Espi-7557,
Please change your following codes

public ICollection<hg_applications> applications { get; set; } public ICollection<hg_hotfixes> hotfixes { get; set; }

to

public ICollection<applications> applications { get; set; } public ICollection<hotfixes> hotfixes { get; set; }

And you can also try to use List<> instead of ICollection<> .
Best Regards,
Daniel Zhang

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EF Core related entities only returns one record in a one-to-many relationship

Your answer