105 lines
2.5 KiB
Markdown
105 lines
2.5 KiB
Markdown
---
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categories:
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- Programming Languages
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tags: [backend, node-js, REST, APIs]
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---
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# Creating a RESTful API: `GET` requests
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With our GET request we will simply return the array of course objects.
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We create an [event emitter](Events%20module.md#event-emitters) and listener
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that listens for GET requests on a specified port and sends data in response to
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requests.
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```js
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// Return a value as response from specified URI
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router.get("/", (req, res) => {
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res.send(courses);
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});
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```
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Our server is now set up:
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> When creating our API this structure of creating handlers for specific routes
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> will be iterated. Every endpoint will be specified with
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> `[app].[http_request_type]` and followed by a callback.
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We can now call the endpoint:
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```js
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const getAllCourses = async () => {
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try {
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const resp = await axios.get("http://localhost:3000/api/courses");
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console.log(resp.data);
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} catch (err) {
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console.error(err);
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}
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};
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getAllCourses();
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```
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Returns:
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```js
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[
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{ id: 1, name: "First course" },
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{ id: 2, name: "Second course" },
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{ id: 3, name: "Third course" },
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];
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```
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## Parameters
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The previous example serves the entire set of our data. But we will also need to
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retrieve specific values, we do this by adapting the GET callback to accept
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parameters. These parameters will correspond to the specific entry in our main
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data array.
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```js
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router.get("/:id", (req, res) => {
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res.send(req.params.id);
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});
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```
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We use the `:` symbol in the URI to indicate that we looking to parse for a
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specific value in the data. Now if we call `/api/courses/2`, we will get the
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second item in the array.
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The block above is the most basic format but we would want to add some kind of
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error handling, for example:
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```js
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router.get("/:id", (req, res) => {
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const course = courses.find((c) => c.id === parseInt(req.params.id));
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if (!course) res.status(404).send("A course with the given ID was not found");
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res.send(course);
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});
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```
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## Queries
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Whereas parameters return specific data points, queries don't get data they
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aggregate or present the data that is returned in a certain way, such as for
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instance applying a search function. We indicate queries with a `?` in our URI.
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For example: `/api/posts/2018/1?sortBy=name`. To facilitate a request like this
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we have to create a GET path that allows for it:
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```js
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router.get("/:year/:month", (req, res) => {
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res.send(req.query);
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})[]();
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```
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We would get the following back:
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```json
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{
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"sortBy": "name"
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}
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```
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Again a JSON object with key-value pairs is returned.
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