91 lines
1.9 KiB
Markdown
91 lines
1.9 KiB
Markdown
---
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tags: [backend, node-js, REST, APIs]
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---
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# Creating a RESTful API: `POST` requests
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To demonstrate the handling of POST requests, we will create a handler that add
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a new element to the array of courses.
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```js
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router.post("/", (req, res) => {
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const course = {
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id: courses.length + 1,
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name: req.body.name,
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};
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courses.push(course);
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res.send(course);
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});
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```
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Here we use the body that is sent from the client and isolate the field `name`.
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This presupposes that the client is sending us data with the following shape as
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the body:
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```json
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{
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"name": "Biology and Life Sciences"
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}
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```
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To execute the PUT request from the frontend:
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```js
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const addCourse = async (newCourse) => {
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try {
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const resp = await axios.post("http://localhost:3000/api/courses", {
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name: newCourse,
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});
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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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addCourse("Biology and Life Sciences");
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```
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Which returns:
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```js
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{ id: 4, name: 'Biology and Life Sciences' }
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```
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The `id` is added by the server, not the client. Having created the new value we
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add it to our `courses` array. (In reality we would be creating a new entry in a
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database.) Then we follow the convention of returning the new value back to the
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client.
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## Validation
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We should accept alterations to the database that are not first validated. We
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can use the
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[Joi validator](Validation.md) to vet
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the request:
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```js
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function validateCourse(course) {
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const schema = Joi.object({
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name: Joi.string().min(3).required(),
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});
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const { error } = schema.validate(course);
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return error;
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}
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```
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We can then add the validation as part of our general error handling:
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```js
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router.post("/", (req, res) => {
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const course = {
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id: courses.length + 1,
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name: req.body.name,
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};
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const { error } = schema.validate(req.body);
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if (error)
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return error.details.map((joiErr) => res.status(400).send(joiErr.message));
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courses.push(course);
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res.send(course);
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});
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```
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