Loopback 4 The swagger generated filters don't seem to work

I set up a basic model and controller connected to mysql database. Everything looks good and is working.

My Definition Model looks like this.

import { Entity, model, property } from '@loopback/repository';

@model({
  settings: {
    mysql: {
      table: 'definition'
    }
  }
})
export class Definition extends Entity {
  @property({
    type: 'number',
    id: true,
    generated: true,
    forceId: true,
    required: false,
    description: 'The unique identifier for a definition',
  })
  id: number;

  @property({
    type: 'string',
    required: true,
  })
  name: string;

  @property({
    type: 'string',
    required: true,
  })
  process_id: string;


  constructor(data?: Partial<Definition>) {
    super(data);
  }
}

export interface DefinitionRelations {
  // describe navigational properties here
}

export type DefinitionWithRelations = Definition & DefinitionRelations;

When I have it up and running and click on the explorer to test it out.

I click on "Try it out" for get /definitions and the only editable field that gets enabled is the filter field.

It is repopulated with a value like this...

 {
  "where": {},
  "fields": {
    "id": true,
    "name": true,
    "process_id": true
  },
  "offset": 0,
  "limit": 0,
  "skip": 0,
  "order": [
    "string"
  ]
}

I have to clear that to get it to work which is fine. When I run it with no filter it returns these results.

[
  {
    "id": 10,
    "name": "Place Manual Payoff Order Process Config",
    "process_id": "Process_PlaceManualPayoffOrderProcessConfig"
  },
  {
    "id": 11,
    "name": "test",
    "process_id": "Test"
  },
  {
    "id": 12,
    "name": "test2",
    "process_id": "test2"
  }
]

I am trying to use the filter expression to only return ones with a specific process_id field. So I change the filter to look like this.

{
  "where": {"process_id": "test2"}
}

And it still returns the same results.

[
  {
    "id": 10,
    "name": "Place Manual Payoff Order Process Config",
    "process_id": "Process_PlaceManualPayoffOrderProcessConfig"
  },
  {
    "id": 11,
    "name": "test",
    "process_id": "Test"
  },
  {
    "id": 12,
    "name": "test2",
    "process_id": "test2"
  }
]

Do filters currently work in Loopback 4 or am I using them incorrectly?

EDIT: if I post the filters in the URL string they work. It seems as though the openapi ui isn't generating that part of the filter Into the URL string.

Solution

It seems as though the openapi ui isn't generating that part of the filter Into the URL string.

Yes, this a precise description.

OpenAPI Spec version 3.x does not specify how to serialize deeply-nested values to URL queries and swagger-js, the library powering swagger-ui (which powers LoopBack's REST API Explorer), silently ignores such values.

The issue has been reported and is being discussed here: