begin work on emberjs/rfcs#793

packages/-ember-data/tests/integration/relationships/explicit-polymorphism-test.js

@@ -0,0 +1,192 @@
+import { module, test } from 'qunit';
+
+import { setupTest } from 'ember-qunit';
+
+import Model, { attr, belongsTo } from '@ember-data/model';
+import { recordIdentifierFor } from '@ember-data/store';
+
+class FrameworkClass {
+  constructor(args) {
+    Object.assign(this, args);
+  }
+
+  static create(args) {
+    return new this(args);
+  }
+}
+
+module('Integration | Relationships | Explicit Polymorphism', function (hooks) {
+  setupTest(hooks);
+
+  test('We can fetch a polymorphic belongsTo relationship with a null inverse', async function (assert) {
+    const { owner } = this;
+    const store = owner.lookup('service:store');
+
+    owner.register(
+      'model:tag',
+      class extends Model {
+        @attr name;
+        @belongsTo('taggable', { async: false, inverse: null, polymorphic: true }) tagged;
+      }
+    );
+    owner.register(
+      'model:comment',
+      class extends Model {
+        @attr name;
+      }
+    );
+    owner.register(
+      'model:post',
+      class extends Model {
+        @attr name;
+      }
+    );
+
+    owner.register(
+      'adapter:application',
+      class extends FrameworkClass {
+        findRecord(store, schema, id, snapshot) {
+          return {
+            data: {
+              type: 'comment',
+              id,
+              attributes: {
+                name: 'My Comment',
+              },
+            },
+          };
+        }
+      }
+    );
+    owner.register(
+      'serializer:application',
+      class extends FrameworkClass {
+        normalizeResponse(_, __, data) {
+          return data;
+        }
+      }
+    );
+
+    const tag = store.push({
+      data: {
+        type: 'tag',
+        id: '1',
+        attributes: { name: 'My Tag' },
+        relationships: {
+          tagged: {
+            // we expect the store to not error on push for this unknown model name
+            data: { type: 'comment', id: '1' },
+          },
+        },
+      },
+    });
+
+    assert.strictEqual(tag.name, 'My Tag', 'We pushed the Tag');
+    assert.strictEqual(tag.belongsTo('tagged').id(), '1', 'we have the data for the relationship');
+
+    await store.findRecord('comment', '1');
+
+    assert.strictEqual(tag.tagged.id, '1', 'we have the loaded comment');
+    assert.strictEqual(tag.tagged.name, 'My Comment', 'Comment is correct');
+    assert.strictEqual(tag.tagged.constructor.modelName, 'comment', 'model name is correct');
+    const identifier = recordIdentifierFor(tag.tagged);
+    assert.strictEqual(identifier.type, 'comment', 'identifier type is correct');
+
+    // update the value
+    const post = store.push({
+      data: {
+        type: 'post',
+        id: '1',
+        attributes: { name: 'My Post' },
+      },
+    });
+    tag.tagged = post;
+    assert.strictEqual(tag.tagged.id, '1', 'we have the loaded post');
+    assert.strictEqual(tag.tagged.name, 'My Post', 'Post is correct');
+    assert.strictEqual(tag.tagged.constructor.modelName, 'post', 'model name is correct');
+    const identifier2 = recordIdentifierFor(tag.tagged);
+    assert.strictEqual(identifier2.type, 'post', 'identifier type is correct');
+  });
+
+  test('We can fetch a polymorphic belongsTo relationship with a specified inverse', async function (assert) {
+    const { owner } = this;
+    const store = owner.lookup('service:store');
+
+    owner.register(
+      'model:tag',
+      class extends Model {
+        @attr name;
+        @belongsTo('taggable', { async: false, inverse: 'tag', polymorphic: true }) tagged;
+      }
+    );
+    owner.register(
+      'model:comment',
+      class extends Model {
+        @attr name;
+        @belongsTo('tag', { async: false, inverse: 'tagged', as: 'taggable' }) tag;
+      }
+    );
+    owner.register(
+      'model:post',
+      class extends Model {
+        @attr name;
+        @belongsTo('tag', { async: false, inverse: 'tagged', as: 'taggable' }) tag;
+      }
+    );
+
+    owner.register(
+      'adapter:application',
+      class extends FrameworkClass {
+        findRecord(store, schema, id, snapshot) {
+          return {
+            data: {
+              type: 'comment',
+              id,
+              attributes: {
+                name: 'My Comment',
+              },
+            },
+          };
+        }
+      }
+    );
+    owner.register(
+      'serializer:application',
+      class extends FrameworkClass {
+        normalizeResponse(_, __, data) {
+          return data;
+        }
+      }
+    );
+
+    const post = store.push({
+      data: {
+        type: 'post',
+        id: '1',
+        attributes: { name: 'My Post' },
+        relationships: {
+          tag: {
+            // we expect the store to not error on push for this unknown model name
+            data: { type: 'tag', id: '1' },
+          },
+        },
+      },
+      included: [
+        {
+          type: 'tag',
+          id: '1',
+          attributes: { name: 'My Tag' },
+          relationships: {
+            tagged: {
+              // we expect the store to not error on push for this unknown model name
+              data: { type: 'post', id: '1' },
+            },
+          },
+        },
+      ],
+    });
+    const tag = store.peekRecord('tag', '1');
+
+    assert.strictEqual(post.tag, tag, 'we have a tag');
+  });
+});

packages/model/addon/-private/model.js

@@ -1288,6 +1288,9 @@ class Model extends EmberObject {
         this.modelName
       );
     }
+    if (!store.getSchemaDefinitionService().doesTypeExist(name)) {
+      return null;
+    }
     let relationship = this.relationshipsByName.get(name);
     return relationship && store.modelFor(relationship.type);
   }
@@ -1395,11 +1398,13 @@ class Model extends EmberObject {
       );
     }
     let inverseType = this.typeForRelationship(name, store);
-    if (!inverseType) {
+    let propertyMeta = this.metaForProperty(name);
+
+    if (!inverseType && !propertyMeta.options.polymorphic) {
+      // TODO still error?
       return null;
     }
 
-    let propertyMeta = this.metaForProperty(name);
     //If inverse is manually specified to be null, like  `comments: hasMany('message', { inverse: null })`
     let options = propertyMeta.options;
     if (options.inverse === null) {
@@ -1409,23 +1414,25 @@ class Model extends EmberObject {
     let inverseName, inverseKind, inverse, inverseOptions;
 
     //If inverse is specified manually, return the inverse
-    if (options.inverse) {
+    if ((!options.polymorphic || inverseType) && options.inverse) {
       inverseName = options.inverse;
-      inverse = inverseType.relationshipsByName.get(inverseName);
+      inverse = inverseType && inverseType.relationshipsByName.get(inverseName);
 
-      assert(
-        "We found no inverse relationships by the name of '" +
-          inverseName +
-          "' on the '" +
-          inverseType.modelName +
-          "' model. This is most likely due to a missing attribute on your model definition.",
-        !isNone(inverse)
-      );
+      if (!options.polymorphic) {
+        assert(
+          "We found no inverse relationships by the name of '" +
+            inverseName +
+            "' on the '" +
+            inverseType.modelName +
+            "' model. This is most likely due to a missing attribute on your model definition.",
+          !isNone(inverse)
+        );
+      }
 
       // TODO probably just return the whole inverse here
       inverseKind = inverse.kind;
       inverseOptions = inverse.options;
-    } else {
+    } else if (!options.inverse) {
       //No inverse was specified manually, we need to use a heuristic to guess one
       if (propertyMeta.type === propertyMeta.parentModelName) {
         warn(
@@ -1481,10 +1488,15 @@ class Model extends EmberObject {
       inverseOptions = possibleRelationships[0].options;
     }
 
-    assert(
-      `The ${inverseType.modelName}:${inverseName} relationship declares 'inverse: null', but it was resolved as the inverse for ${this.modelName}:${name}.`,
-      !inverseOptions || inverseOptions.inverse !== null
-    );
+    if (inverseOptions?.polymorphic) {
+      // validate
+      assert(`these should match`, !!options.as && inverse.type === options.as);
+    } else {
+      assert(
+        `The ${inverseType.modelName}:${inverseName} relationship declares 'inverse: null', but it was resolved as the inverse for ${this.modelName}:${name}.`,
+        !inverseOptions || inverseOptions.inverse !== null
+      );
+    }
 
     return {
       type: inverseType,

packages/model/addon/-private/relationship-meta.ts

@@ -75,7 +75,9 @@ class RelationshipDefinition implements RelationshipSchema {
 
     if (shouldFindInverse(this.meta)) {
       inverse = modelClass.inverseFor(this.key, store);
-    } else if (DEBUG) {
+    }
+    // TODO make this error again for the non-polymorphic case
+    if (DEBUG && !this.options.polymorphic) {
       modelClass.typeForRelationship(this.key, store);
     }
 

packages/record-data/addon/-private/graph/-edge-definition.ts

@@ -175,13 +175,30 @@ export function upgradeDefinition(
 
   // CASE: Inverse is explicitly null
   if (definition.inverseKey === null) {
+    // TODO probably dont need this assertion if polymorphic
     assert(`Expected the inverse model to exist`, getStore(storeWrapper).modelFor(inverseType));
     inverseDefinition = null;
   } else {
     inverseKey = inverseForRelationship(getStore(storeWrapper), identifier, propertyName);
 
-    // CASE: Inverse resolves to null
-    if (!inverseKey) {
+    // CASE: If we are polymorphic, and we declared an inverse that is non-null
+    // we must assume that the lack of inverseKey means that there is no
+    // concrete type as the baseType, so we must construct and artificial
+    // placeholder
+    if (!inverseKey && definition.isPolymorphic && definition.inverseKey) {
+      inverseDefinition = {
+        kind: 'belongsTo', // this must be updated when we find the first belongsTo or hasMany definition that matches
+        key: definition.inverseKey,
+        type: type,
+        isAsync: false, // this must be updated when we find the first belongsTo or hasMany definition that matches
+        isImplicit: false,
+        isCollection: false, // this must be updated when we find the first belongsTo or hasMany definition that matches
+        isPolymorphic: false,
+        isInitialized: false, // tracks whether we have seen the other side at least once
+      };
+
+      // CASE: Inverse resolves to null
+    } else if (!inverseKey) {
       inverseDefinition = null;
     } else {
       // CASE: We have an explicit inverse or were able to resolve one

packages/record-data/addon/-private/graph/operations/replace-related-record.ts

@@ -103,7 +103,13 @@ export default function replaceRelatedRecord(graph: Graph, op: ReplaceRelatedRec
 
   if (op.value) {
     if (definition.type !== op.value.type) {
-      assertPolymorphicType(relationship.identifier, definition, op.value, graph.store);
+      if (!definition.isPolymorphic) {
+        // TODO this should now handle the deprecation warning if isPolymorphic is not set
+        // but the record does turn out to be polymorphic
+        // this should still assert if the user is relying on legacy inheritance/mixins to
+        // provide polymorphic behavior and has not yet added the polymorphic flags
+        assertPolymorphicType(relationship.identifier, definition, op.value, graph.store);
+      }
       graph.registerPolymorphicType(definition.type, op.value.type);
     }
     addToInverse(graph, op.value, definition.inverseKey, op.record, isRemote);