Add backendResourceName for model and store

When using `model.toBackendAll()`, the name of the relation is sometimes
not the same as the name of the model or store. e.g.

```js
relations() {
	return { activities: ActivityStore };
}
```

But the backend knows the `activities` relation by the name `activity`.
To fix this, you can now set `backendResourceName` on a model or store:

```js
class ActivityStore extends Store {
	static backendResourceName = 'activity';
}
```

src/Model.js

@@ -25,6 +25,8 @@ function generateNegativeId() {
 
 export default class Model {
     static primaryKey = 'id';
+    // How the model is known at the backend. This is useful when the model is in a relation that has a different name.
+    static backendResourceName = '';
     urlRoot;
 
     __attributes = [];
@@ -61,6 +63,12 @@ export default class Model {
         );
     }
 
+    set backendResourceName(v) {
+        throw new Error(
+            '`backendResourceName` should be a static property on the model.'
+        );
+    }
+
     casts() {
         return {};
     }
@@ -176,7 +184,12 @@ export default class Model {
                 data[relBackendName] = myNewId;
             }
             const relBackendData = rel.toBackendAll(myNewId);
-            relations[relBackendName] = relBackendData.data;
+            // Sometimes the backend knows the relation by a different name, e.g. the relation is called
+            // `activities`, but the name in the backend is `activity`.
+            // In that case, you can add `static backendResourceName = 'activity';` to that model.
+            const realBackendName =
+                rel.constructor.backendResourceName || relBackendName;
+            relations[realBackendName] = relBackendData.data;
             forIn(relBackendData.relations, (relB, key) => {
                 relations[key] = relations[key]
                     ? relations[key].concat(relB)

src/Store.js

@@ -28,6 +28,7 @@ export default class Store {
     api = null;
     __repository;
     __nestedRepository = {};
+    static backendResourceName = '';
 
     @computed get isLoading() {
         return this.__pendingRequestCount > 0;
@@ -37,6 +38,12 @@ export default class Store {
         return this.models.length;
     }
 
+    set backendResourceName(v) {
+        throw new Error(
+            '`backendResourceName` should be a static property on the store.'
+        );
+    }
+
     constructor(options = {}) {
         if (!isPlainObject(options)) {
             throw Error(

src/__tests__/Model.js

@@ -11,6 +11,7 @@ import {
     AnimalWithoutApi,
     AnimalWithoutUrl,
     AnimalCircular,
+    AnimalResourceName,
     Kind,
     Breed,
     Person,
@@ -423,6 +424,40 @@ test('toBackendAll with nested store relation', () => {
     expect(serialized).toMatchSnapshot();
 });
 
+test('toBackendAll with `backendResourceName` property model', () => {
+    const animal = new AnimalResourceName(
+        {},
+        { relations: ['blaat', 'owners'] }
+    );
+
+    animal.parse({
+        id: 1,
+        blaat: {
+            id: 2,
+        },
+        owners: [
+            {
+                id: 3,
+            },
+        ],
+    });
+
+    const serialized = animal.toBackendAll();
+    expect(serialized).toMatchSnapshot();
+});
+
+test('backendResourceName defined as not static should throw error', () => {
+    class Zebra extends Model {
+        backendResourceName = 'blaat';
+    }
+
+    expect(() => {
+        return new Zebra();
+    }).toThrow(
+        '`backendResourceName` should be a static property on the model.'
+    );
+});
+
 test('toBackend with frontend-only prop', () => {
     const animal = new AnimalWithFrontendProp({
         id: 3,

src/__tests__/Store.js

@@ -1,5 +1,6 @@
 import axios from 'axios';
 import MockAdapter from 'axios-mock-adapter';
+import { Store } from '../';
 import {
     Animal,
     AnimalStore,
@@ -260,6 +261,18 @@ test('clear models', () => {
     expect(animalStore.length).toBe(0);
 });
 
+test('backendResourceName defined as not static should throw error', () => {
+    class Zebra extends Store {
+        backendResourceName = 'blaat';
+    }
+
+    expect(() => {
+        return new Zebra();
+    }).toThrow(
+        '`backendResourceName` should be a static property on the store.'
+    );
+});
+
 test('One-level store relation', () => {
     const animalStore = new AnimalStore({
         relations: ['pastOwners'],

src/__tests__/__snapshots__/Model.js.snap

@@ -1,5 +1,31 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
+exports[`toBackendAll with \`backendResourceName\` property model 1`] = `
+Object {
+  "data": Array [
+    Object {
+      "blaat": 2,
+      "id": 1,
+      "owners": Array [
+        3,
+      ],
+    },
+  ],
+  "relations": Object {
+    "kind": Array [
+      Object {
+        "id": 2,
+      },
+    ],
+    "person": Array [
+      Object {
+        "id": 3,
+      },
+    ],
+  },
+}
+`;
+
 exports[`toBackendAll with deep nested relation 1`] = `
 Object {
   "data": Array [

src/__tests__/fixtures/Animal.js

@@ -102,3 +102,27 @@ export class AnimalCircular extends Model {
         };
     }
 }
+
+export class KindResourceName extends Model {
+    api = new BinderApi();
+    static backendResourceName = 'kind';
+    @observable id = null;
+}
+
+export class PersonStoreResourceName extends Store {
+    Model = KindResourceName;
+    static backendResourceName = 'person';
+    api = new BinderApi();
+}
+
+export class AnimalResourceName extends Model {
+    api = new BinderApi();
+    @observable id = null;
+
+    relations() {
+        return {
+            blaat: KindResourceName,
+            owners: PersonStoreResourceName,
+        };
+    }
+}