Fix self referential relationships silently failing

src/util/deserialize.ts

@@ -100,11 +100,14 @@ class Deserializer {
     record: SpraypaintBase
   ): void {
     const modelIdx = model as any
-    const associationRecords = modelIdx[associationName]
+    const associationRecords = modelIdx[associationName] || []
     const existingInstance = this.lookupAssociated(associationRecords, record)
 
-    if (!existingInstance) {
+    if (existingInstance) return
+    if (Array.isArray(modelIdx[associationName])) {
       modelIdx[associationName].push(record)
+    } else {
+      modelIdx[associationName] = record
     }
   }
 
@@ -199,7 +202,7 @@ class Deserializer {
         if (Array.isArray(relationData)) {
           for (const datum of relationData) {
             const hydratedDatum = this.findResource(datum)
-            const associationRecords = instanceIdx[relationName]
+            const associationRecords = instanceIdx[relationName] || []
             let relatedInstance = this.relationshipInstanceFor(
               hydratedDatum,
               associationRecords

test/fixtures.ts

@@ -119,6 +119,8 @@ export class Genre extends ApplicationRecord {
 
   @Attr name!: string
   @HasMany("authors") authors: any
+
+  @BelongsTo({ type: "genres" }) parentGenre?: Genre
 }
 
 @Model()

test/integration/relations.test.ts

@@ -1,5 +1,5 @@
 import { expect, fetchMock } from "../test-helper"
-import { Author, NonFictionAuthor } from "../fixtures"
+import { Author, Book, Genre, NonFictionAuthor } from "../fixtures"
 import { IResultProxy } from "../../src/proxies/index"
 import { SpraypaintBase } from "../../src/index"
 
@@ -55,6 +55,54 @@ const generateMockResponse = (type: string) => {
   } as any
 }
 
+const generateMockGenreResponse = () => {
+  return {
+    data: {
+      id: "1",
+      type: "books",
+      attributes: {
+        title: "A Song of Ice and Fire"
+      },
+      relationships: {
+        genre: {
+          data: [
+            {
+              id: "genre1",
+              type: "genres"
+            }
+          ]
+        }
+      }
+    },
+    included: [
+      {
+        id: "genre1",
+        type: "genres",
+        attributes: {
+          title: "Sword and Sourcery"
+        },
+        relationships: {
+          parentGenre: {
+            data: [
+              {
+                id: "genre2",
+                type: "genres"
+              }
+            ]
+          }
+        }
+      },
+      {
+        id: "genre2",
+        type: "genres",
+        attributes: {
+          title: "Fantasy"
+        }
+      }
+    ]
+  } as any
+}
+
 describe("Relations", () => {
   describe("#find()", () => {
     beforeEach(() => {
@@ -98,6 +146,23 @@ describe("Relations", () => {
         expect(data.genre).to.eq(undefined)
       })
     })
+
+    describe("when there's a self-referential relationship", () => {
+      beforeEach(() => {
+        const response = generateMockGenreResponse()
+        fetchMock.get(
+          "http://example.com/api/books/1?include=genre.parent_genre",
+          response
+        )
+      })
+
+      it("does not blow up", async () => {
+        const { data } = await Book.includes({ genre: "parentGenre" }).find(1)
+        expect(data.klass).to.eq(Book)
+        expect(data.genre).to.be.instanceOf(Genre)
+        expect(data.genre.parentGenre).to.be.instanceOf(Genre)
+      })
+    })
   })
 
   describe("when keyCase is snake_case", () => {

test/unit/model-relationships.test.ts

@@ -41,4 +41,16 @@ describe("Model relationships", () => {
 
     expect(keys).to.include("genre")
   })
+
+  it("supports self-referential relationships", () => {
+    const genre = new Genre({ name: "Fantasy" })
+    const subgenre = new Genre({
+      name: "Sword and Sourcery",
+      parentGenre: genre
+    })
+
+    expect(genre).to.be.instanceof(Genre)
+    expect(subgenre).to.be.instanceof(Genre)
+    expect(subgenre.parentGenre).to.be.instanceof(Genre)
+  })
 })