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336
ViewsHow to Type a request parameter with express server
How do I Type (typescript) the attached post request to fix the error? I want to get the request body, but I can't type it properly.
Thanks!
import express = require('express');
import { Request } from 'express';
import bodyParser from 'body-parser';
import { parseBMI, calculateBMI } from './bmiCalculator';
import { calculateExercises } from './exerciseCalculator';
const app = express();
app.use(bodyParser.json());
app.get('/hello', (_,res) => {
res.send("Good day");
});
app.get('/bmi', (req,res) => {
const weight = Number(req.query.weight);
const height = Number(req.query.height);
console.log(weight,height);
try {
const {parseHeight, parseWeight} = parseBMI(height,weight);
const out: string = calculateBMI(parseHeight,parseWeight);
res.json({
weight:parseWeight,
height:parseHeight,
bmi:out
});
} catch (e) {
res.status(4004).json(e);
}
});
app.post('/exercises',(req: Request<Array<number>,number>,res) => {
const body:any = req.body;
const dailyExercises = body.daily_exercises as Array<number>;
const target = Number(body.target);
res.json(calculateExercises(dailyExercises,target));
});
const PORT = 3003;
app.listen(PORT, () => {
console.log(`Server running on port ${PORT}`);
});
this is only concerning the /exercises route which throws error with eslint plugin on vscode
2 answers
Answer question0
The out of the box express types support generic parameters, so you can simply pass the type in the signature:
app.post('/foo', async (req: Request<any, any, {bar: string}, any>, res: Response) => {
const x = req.body.bar; //string
}
However, it's worth nothing that this does not perform any validation and is effectively the same thing as the as any cast. A better approach would be to use a library like io-ts or yup to do a validation check. That way you actually know object is in the correct form.
0
You will want to define an interface for your request:
interface Exercise {
dailyExercises: number[],
target: number
}
const exercise = req.body as Exercise
By then casting your req.body to an Exercise, you have an exercise constant that is strictly typed.