Empty attributes returned on overridden relationship endpoint

[alexeidick]

DESCRIPTION

I’m trying to customize the secondary endpoint
/profiles/{id}/groups.

In my data model, Profile has many Groups through a pivot table (ProfileGroup), and Template also has many Groups through another pivot table (TemplateGroup). Each Profile is linked to a single Template.

What I want is that when a client calls /profiles/{id}/groups, the response should contain all groups:
• groups directly linked to the profile, and
• groups linked through the template of that profile.

At the same time, I need to preserve the normal JSON:API behavior:
filters, sorting, pagination, sparse fieldsets (fields), and includes should all still work as if this were a regular HasMany relationship.

STEPS TO REPRODUCE

Features

• Models:
  • Profile (linked to a single Template, many-to-many with Group via ProfileGroup)
  • Template (many-to-many with Group via TemplateGroup, one-to-many with Profile)
  • Group (many-to-many with both Profile and Template)
  • Pivot tables: ProfileGroup, TemplateGroup (with JSON Options field)
• DbContext:
  • Configured for MySQL using Pomelo.EntityFrameworkCore.MySql
  • Relationships and navigation properties set up for EF Core
• JsonApiDotNetCore:
  • Models annotated with [Resource] and inherit from Identifiable<int> for automatic JSON:API endpoints
  • Namespace /api for all resources

Usage

• Start the API and access / to see all available routes.
• JSON:API endpoints are available under /api/groups, /api/profiles, /api/templates, etc.
• The database is seeded with example data on startup.
• Browse the routes:
  • /api/profiles/1/groups
  • /api/profiles/2/groups

EXPECTED BEHAVIOR

Attributes must be filled

/api/profiles/1/groups

{
  "links": {
    ...
  },
  "data": [
    {
      "type": "groups",
      "id": "1",
      "attributes": {
        "name": "Group 1"
      },
      "relationships": {
        ...
      },
      "links": {
        ...
      }
    },
    {
      "type": "groups",
      "id": "2",
      "attributes": {
        "name": "Group 2"
      },
      "relationships": {
        ...
      },
      "links": {
        ...
      }
    }
  ]
}

/api/profiles/2/groups

{
  "links": {
    ...
  },
  "data": [
    {
      "type": "groups",
      "id": "2",
      "attributes": {
        "name": "Group 2"
      },
      "relationships": {
        ...
      },
      "links": {
        ...
      }
    }
  ]
}

ACTUAL BEHAVIOR

Attributes are empty

/api/profiles/1/groups

{
  "links": {
    ...
  },
  "data": [
    {
      "type": "groups",
      "id": "1",
      "attributes": {
        "name": null
      },
      "relationships": {
        ...
      },
      "links": {
        ...
      }
    },
    {
      "type": "groups",
      "id": "2",
      "attributes": {
        "name": null
      },
      "relationships": {
        ...
      },
      "links": {
        ...
      }
    }
  ]
}

/api/profiles/2/groups

{
  "links": {
    ...
  },
  "data": [
    {
      "type": "groups",
      "id": "2",
      "attributes": {
        "name": null
      },
      "relationships": {
        ...
      },
      "links": {
        ...
      }
    }
  ]
}

VERSIONS USED

• JsonApiDotNetCore version: 5.8.1
• ASP.NET Core version: 8.0
• Entity Framework Core version: 9.0.8
• Database provider: MySql

Test repository

https://github.com/alexeidick/json-api-dotnet-relationship-test

[bkoelman]

Thanks. Can you verify if alexeidick/json-api-dotnet-relationship-test#1 resolves the issue?

[alexeidick]

Hi,

Thank you :)

Replace

ResourceType groupType = _graph.GetResourceType<Group>();
QueryLayer secondaryLayer = _composer.ComposeSecondaryLayerForRelationship(groupType);

By

ResourceType groupType = _graph.GetResourceType<Group>();
QueryLayer secondaryLayer = _composer.ComposeFromConstraints(groupType);

Fixed my issue!