relations are not consistently cached

[jasonbodily]

Description

Relations of resources are not predictably made available, even when using the with and bypassCache operators.

Environment

• js-data version: 3.0.8
• node: 10.15.3
• operating system: Catalina

Steps to reproduce

I've included a full example that can be run. The idea is that a user is on one team. Sometimes team information is attached to the serialized object received by the client, and sometimes it isn't. But if it is, it should be available.

1. Copy and run the server with the code below.
2. Invoke the client code function as it is, and you'll find that the team will be logged to the console successfully as expected. This is because the team was included in the user serializer
3. Uncomment out the first request, you'll find that the team is not logged on the first attempt (expected) since it was not on the vanilla serializer. The problem is that it is still not logged on the second request which is explicitly looking for it.

Client Code

import { HttpAdapter } from 'js-data-http'
import { DataStore } from 'js-data'

export default async () => {
  const http = new HttpAdapter({
    basePath: 'http://localhost:3000/api'
  })
  const store = new DataStore({ useFetch: true })
  store.registerAdapter('http', http, { 'default': true })
  store.defineMapper('Team')
  store.defineMapper('User', {
    endpoint: 'users',
    relations: {
      belongsTo: {
        Team: {
          foreignKey: 'team_id',
          localField: 'team'
        }
      }
    }
  })
  // await store.findAll('User', {}, { force: true }).then(users => {
  //   console.log('no_team_expected', users[0].team)
  // })
  store.findAll('User', { serializer: 'include_team' }, { force: true, bypassCache: true, with: ['Team'] }).then(users => {
    console.log('team_expected', users[0].team)
  })
}

Server Code
Download the attached server code, run npm install and node index.js from the root
dev-server.zip
(Contents shown below:)

const express = require('express')
const app = express()
const port = 3000

app.use(express.json())

app.get('/api/users', (request, response) => {
  if (request.query.serializer === 'include_team') {
    response.send([
      {
        "id": "762f9b2c-2af9-4dc0-ba23-768ef035e33e",
        "team": {
          "id": 722,
          "name": "Team A"
        },
        "team_id": 722
      },
      {
        "id": "4b2d480c-e0aa-44e8-93c7-5d7233ab2223",
        "team": {
          "id": 2061,
          "name": "Team B"
        },
        "team_id": 2061,
      }
    ])
  } else {
    response.send([
      {
        "id":"762f9b2c-2af9-4dc0-ba23-768ef035e33e",
        "team_id":722
      },
      {
        "id":"4b2d480c-e0aa-44e8-93c7-5d7233ab2223",
        "team_id":2061
      }
    ])
  }
})

app.listen(port, (err) => {
  if (err) {
    return console.log('something bad happened', err)
  }
  console.log(`server is listening on ${port}`)
})

[crobinson42]

PR's are welcome on this :-)