How to use map in react component using nextjs app?-CodePudding

I have data returned from the backend as an array that i want to populate on react component.

home.js

import Head from "next/head";
import Header from "../src/components/Header";
import * as React from 'react';
import { styled } from '@mui/material/styles';
import Box from '@mui/material/Box';
import Paper from '@mui/material/Paper';
import Grid from '@mui/material/Grid';
import TextField from '@mui/material/TextField';
import SendIcon from '@mui/icons-material/Send';
import Stack from '@mui/material/Stack';
import Button from '@mui/material/Button';
import getDupImages from "../src/services/getDupImages";
import { useState, useEffect } from 'react'

const Item = styled(Paper)(({ theme }) => ({
  backgroundColor: theme.palette.mode === 'dark' ? '#1A2027' : '#fff',
  ...theme.typography.body2,
  padding: theme.spacing(1),
  textAlign: 'center',
  color: theme.palette.text.secondary,
}));

export default function Home({data}) {
  let _data;
  const fetchData = async () => {
    _data = await getDupImages();
    console.log("DATA>>>", _data);
    return _data;
  };
   const submit = (event) => {
    event.preventDefault();
    fetchData();
   }
  return (
    <>
      <Head>
        <title>De-Dup</title>
        <link rel="icon" type="image/ico" href="/img/goals.ico" />
      </Head>
      <Header />
      <section>
      <Box sx={{ flexGrow: 1 }}>
      <Grid container spacing={2}>
        <Grid item xs={5}>
          <Box
              component="form"
               sx={{
                '& > :not(style)': { m: 1, width: '75ch' },
              }}
               noValidate
               autoComplete="off"
            >
            <TextField id="outlined-basic" label="location path" variant="outlined" />
            <Stack direction="row" spacing={2}>
            <Button variant="contained" onClick={submit} endIcon={<SendIcon />}>
              Submit
            </Button>
          </Stack>
        </Box>
        </Grid>
        <Grid item xs={7}>
        {data.map((d) => {
        return (
          <div>
            {d.title}
          </div>
        );
      })}
        </Grid>
      </Grid>
    </Box>
      </section>
    </>
  );
}

Error

1 of 1 unhandled error

Server Error
TypeError: Cannot read property 'map' of undefined

This error happened while generating the page. Any console logs will be displayed in the terminal window.

CodePudding user response：

Put the data in the component state and check if there actually is data before displaying it.

const [data, setData] = useState();
const fetchData = async () => {
   setData(await getDupImages());
}

Then in your JSX:

{!!data && data.map(d => <div>{d.title}</div>}

CodePudding user response：

You are trying to render the data before it is available. Use this instead

{data && data.map((d) => {
    return (
      <div>
        {d.title}
      </div>
    );
  })}

CodePudding user response：

Either initialise the data state as an array or use the Optional chaining (?.) operator before the map function:

data?.map((d) => {
  return <div>{d.title}</div>;
})

Hope this helps.