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KPCKevin Powell - Community

•Created by meku on 7/16/2023 in #front-end

Need help with MaterialUI's Grid component

2 replies

KPCKevin Powell - Community

•Created by meku on 3/13/2023 in #back-end

I don't understand error handling middlewares (Express)

I'm learning from fullstackopen.com and now I'm going into error handling middlewares. This is their demo code for this part : https://github.com/fullstack-hy2020/part3-notes-backend/blob/part3-5/index.js My understanding is that middlewares need to have next() for the next middleware to be executed. Why the demo code shows ...

const errorHandler = (error, request, response, next) => {
  console.error(error.message)

  if (error.name === 'CastError') {
    return response.status(400).send({ error: 'malformatted id' })
  }

  next(error)
}

const unknownEndpoint = (request, response) => {
  response.status(404).send({ error: 'unknown endpoint' })
}

app.use(unknownEndpoint)
app.use(errorHandler)

const errorHandler = (error, request, response, next) => {
  console.error(error.message)

  if (error.name === 'CastError') {
    return response.status(400).send({ error: 'malformatted id' })
  }

  next(error)
}

const unknownEndpoint = (request, response) => {
  response.status(404).send({ error: 'unknown endpoint' })
}

app.use(unknownEndpoint)
app.use(errorHandler)

while there's no next() in unknownEndpoint middleware. How can errorHandler middleware be executed then?

6 replies

KPCKevin Powell - Community

•Created by meku on 3/4/2023 in #front-end

Fetching data from an API and putting them inside an array but it works differently in browser/IDE?

It's React. Something weird happens. When I reload directly from the browser, it still logs an empty array, but when I save the file from VSCode, it displays the array just like I wanted.

const [country, setCountry] = useState([]);

useEffect(() => {
    axios
      .get("https://restcountries.com/v3.1/all")
      .then((response) => {
        const data = response.data;
        const names = data.map((n) => n.name.common);
        setCountry(names);
        console.log(country);
      })
      .catch((error) => {
        console.log(error);
      });
  }, []);

const [country, setCountry] = useState([]);

useEffect(() => {
    axios
      .get("https://restcountries.com/v3.1/all")
      .then((response) => {
        const data = response.data;
        const names = data.map((n) => n.name.common);
        setCountry(names);
        console.log(country);
      })
      .catch((error) => {
        console.log(error);
      });
  }, []);

4 replies

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