unit(query): make query to sift by tags

database/queries/post/sift_by_tags.spec.ts

@@ -0,0 +1,48 @@
+import Model from "%/models/post"
+import Factory from "~/factories/post"
+import TagFactory from "~/factories/tag"
+import PostTagFactory from "~/factories/post_tag"
+
+import siftByTags from "./sift_by_tags"
+
+describe("Database Pipe: Sift by tag", () => {
+	it("can find on specific tag", async() => {
+		const tag = await new TagFactory().insertOne()
+		const model = await new Factory().insertOne()
+		await new PostTagFactory()
+		.post(() => Promise.resolve(model))
+		.tag(() => Promise.resolve(tag))
+		.insertOne()
+
+		const options = siftByTags({}, {
+			"filter": {
+				"tagIDs": [ tag.id ]
+			}
+		})
+		const foundModels = await Model.findAll(options)
+
+		expect(options).toHaveProperty("include")
+		expect(foundModels).toHaveLength(1)
+		expect(foundModels).toHaveProperty("0.id", model.id)
+	})
+
+	it("cannot find on empty tag", async() => {
+		const tagA = await new TagFactory().insertOne()
+		const tagB = await new TagFactory().insertOne()
+		const model = await new Factory().insertOne()
+		await new PostTagFactory()
+		.post(() => Promise.resolve(model))
+		.tag(() => Promise.resolve(tagA))
+		.insertOne()
+
+		const options = siftByTags({}, {
+			"filter": {
+				"tagIDs": [ tagB.id ]
+			}
+		})
+		const foundModels = await Model.findAll(options)
+
+		expect(options).toHaveProperty("include")
+		expect(foundModels).toHaveLength(0)
+	})
+})

database/queries/post/sift_by_tags.ts

@@ -17,8 +17,9 @@ export default function<T>(
 ): FindOptions<T> {
 	const newState = { ...currentState }
 
-	const condition = new Condition()
 	if (constraints.filter.tagIDs !== "*") {
+		const condition = new Condition()
+
 		condition.isIncludedIn("id", constraints.filter.tagIDs)
 
 		if (isUndefined(newState.include)) {