[fix] Allow Resource to have 'url' member (#107)

src/__tests__/common.ts

@@ -87,6 +87,9 @@ export class ArticleResource extends Resource {
   }
 }
 
+export class UrlArticleResource extends ArticleResource {
+  readonly url: string = 'happy.com';
+}
 
 export class CoolerArticleResource extends ArticleResource {
   static urlRoot = 'http://test.com/article-cooler/';

src/resource/Resource.ts

@@ -150,10 +150,12 @@ export default abstract class Resource {
 
   /** URL to find this Resource */
   get url(): string {
+    if (this.__url !== undefined) return this.__url;
     // typescript thinks constructor is just a function
     const Static = this.constructor as typeof Resource;
     return Static.url(this);
   }
+  private __url?: string;
 
   /** Get the url for a Resource
    *
@@ -237,7 +239,9 @@ export default abstract class Resource {
     const getFetchKey = (params: Readonly<object>) => {
       return 'GET ' + this.url(params);
     };
-    const schema: SchemaDetail<AbstractInstanceType<T>> = this.getEntitySchema();
+    const schema: SchemaDetail<
+      AbstractInstanceType<T>
+    > = this.getEntitySchema();
     const options = this.getRequestOptions();
     return {
       type: 'read',
@@ -363,3 +367,11 @@ export default abstract class Resource {
     };
   }
 }
+
+// We're only allowing this to get set for descendants but
+// by default we want Typescript to treat it as readonly.
+Object.defineProperty(Resource.prototype, 'url', {
+  set(url: string) {
+    this.__url = url;
+  },
+});

src/resource/__tests__/resource.ts

@@ -1,6 +1,6 @@
 import nock from 'nock';
 
-import { CoolerArticleResource, UserResource } from '../../__tests__/common';
+import { CoolerArticleResource, UserResource, UrlArticleResource } from '../../__tests__/common';
 import { Resource, normalize } from '..';
 
 describe('Resource', () => {
@@ -20,6 +20,12 @@ describe('Resource', () => {
   it('should not init Resource itself', () => {
     expect(() => Resource.fromJS({})).toThrow();
   });
+  it('should work with `url` member', () => {
+    expect(() => UrlArticleResource.fromJS({})).not.toThrow();
+    expect(() => UrlArticleResource.fromJS({url: 'five'})).not.toThrow();
+    const urlArticle = UrlArticleResource.fromJS({url: 'five'});
+    expect(urlArticle.url).toBe('five');
+  });
   it('should convert class to string', () => {
     expect(CoolerArticleResource.toString()).toBeDefined();
     expect(CoolerArticleResource.toString()).toMatchInlineSnapshot(