feat: cursor (marker) pagination

alexx666 · Apr 18, 2021 · 8229047 · 8229047
1 parent 03f73a7
commit 8229047
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Showing 5 changed files with 21 additions and 18 deletions.
diff --git a/src/api/routers/todos/list.router.ts b/src/api/routers/todos/list.router.ts
@@ -9,7 +9,7 @@ export default function(listTodos: ListTodos) {
 			try {
 					const request: ListTodosRequest = {
 						limit: Number(req.query.limit) || 20,
-						skip: Number(req.query.skip) || 0
+						marker: String(req.query.marker)
 					}
 
 					const response = await listTodos.execute(request)

diff --git a/src/cli/commands/todos/list-todos.ts b/src/cli/commands/todos/list-todos.ts
@@ -14,7 +14,7 @@ export default function (listTodos: ListTodos) {
         try {
             const request: ListTodosRequest = {
 							limit: Number(cmd.limit),
-							skip: Number(cmd.skip)
+							marker: String(cmd.marker)
 						}
 
             const response = await listTodos.execute(request)

diff --git a/src/modules/todos/boundry/list-todos.ts b/src/modules/todos/boundry/list-todos.ts
@@ -1,6 +1,6 @@
 export interface ListTodosRequest {
     limit: number
-		skip: number
+		marker?: string
 }
 
 export interface ListTodosResponse {

diff --git a/src/providers/todo-in-memory/todo-in-memory.gateway.spec.ts b/src/providers/todo-in-memory/todo-in-memory.gateway.spec.ts
@@ -5,7 +5,7 @@ import InMemoryTodoGateway from "./todo-in-memory.gateway";
 describe("[InMemoryTodoGateway] Initialization", () => {
 	it("should create an in memory todo gateway without any todos", async () => {
 		const inMemTodoGW = new InMemoryTodoGateway()
-		const todos = await inMemTodoGW.find({ limit: 10, skip: 0 })
+		const todos = await inMemTodoGW.find({ limit: 10 })
 		expect(todos.length).toEqual(0)
 		expect.assertions(1)
 	})
@@ -26,24 +26,23 @@ describe("[InMemoryTodoGateway] Test Cases", () => {
 	})
 
 	it("should return all items in map as todos", async () => {
-		const todos = await inMemTodoGW.find({ limit: 10, skip: 0 })
+		const todos = await inMemTodoGW.find({ limit: 10 })
 		expect(todos.length).toEqual(3)
 		expect.assertions(1)
 	})
 
 	it("should return second todo", async () => {
-		expect.assertions(2)
-		const todos = await inMemTodoGW.find({ limit: 1, skip: 1 })
+		const todos = await inMemTodoGW.find({ limit: 1, marker: "1" })
 		expect(todos.length).toEqual(1)
 		expect(todos[0].id).toEqual("2")
+		expect.assertions(2)
 	})
 
 	it("should add a new todo and return it", async () => {
-		const todo = await inMemTodoGW.save(new Todo("4", "forth", new Date()));
-		const todos = await inMemTodoGW.find({ limit: 1, skip: 3 })
-		expect(todos.length).toEqual(1)
-		expect(todos[0]).toEqual(todo)
-		expect.assertions(2)
+		const newTodo = new Todo("4", "forth", new Date())
+		const savedTodo = await inMemTodoGW.save(newTodo);
+		expect(savedTodo).toEqual(newTodo)
+		expect.assertions(1)
 	})
 
 	it("should throw an error because the todo already exist", async () => {
@@ -57,7 +56,7 @@ describe("[InMemoryTodoGateway] Test Cases", () => {
 
 	it("should remove a todo and return its value", async () => {
 		const todo = await inMemTodoGW.delete("3");
-		const todos = await inMemTodoGW.find({ limit: 10, skip: 0 })
+		const todos = await inMemTodoGW.find({ limit: 10 })
 		expect(todos).not.toContain(todo)
 		expect(todos.length).toEqual(2)
 		expect.assertions(2)

diff --git a/src/providers/todo-in-memory/todo-in-memory.gateway.ts b/src/providers/todo-in-memory/todo-in-memory.gateway.ts
@@ -4,7 +4,7 @@ import TodoDocument from "./todo-document";
 
 interface FindQuery {
     limit: number;
-		skip: number;
+		marker?: string;
 }
 
 export default class InMemoryTodoGateway implements ReadableGateway<Todo>, WritableGateway<Todo> {
@@ -30,12 +30,16 @@ export default class InMemoryTodoGateway implements ReadableGateway<Todo>, Writa
     }
 
     public async find(query: FindQuery): Promise<Todo[]> {
-        const { limit, skip } = query;
+        const { limit, marker } = query;
 
-        const keys = Array.from(this.documents.keys()).filter((_, i) => i >= skip && i < limit + skip)
+        const keys = Array.from(this.documents.keys())
 
-        const docs = keys.map(key => this.documents.get(key)!);
+				// TODO: apply filter/sort
 
-        return docs.map((d, i) => d.toEntity(keys[i]))
+				const offset = marker ? keys.indexOf(marker) + 1 : 0;
+
+				const filteredKeys = keys.filter((_, i) => i >= offset && i < limit + offset);
+
+        return filteredKeys.map(key => this.documents.get(key)!.toEntity(key));
     }
 }