如何从快速后端服务器获取图像并将其显示到 React js 前端? [英] How to Fetch and Display an Image from an express backend server to a React js frontend?

问题描述

我正在尝试从快速后端获取图像并将它们显示在 react js 前端中.我怎样才能完美地做到这一点?

我尝试获取保存在名为Backup"的后端文件夹中的图像，并将它们显示回 react js 前端中的用户.我已经使用 axios 尝试过这个，但仍然得到一个无效的图像而不是正确的图像.

下面是我在前端的获取请求.

fetchImages = () =>{const imageName = 'garande.png'const url = `http://localhost:5000/fetchImage/${imageName}`axios.get(url, {responseType: 'blob'}).then(res => {返回(<img src={res.data} alt="试用"/>)}}

这是我在后端的 server.js 文件中的内容

app.get('/fetchImage/:file(*)', (req, res) => {让文件 = req.params.file;let fileLocation = path.join('../Backup/images/', file);//res.send({image: fileLocation});res.sendFile(`${fileLocation}`)})

我希望图像显示在用户页面中.谢谢.

解决方案

这对我有用:

导出异步函数 get(url: string) {尝试 {const response = await fetch(url, {method: 'GET',//*GET、POST、PUT、DELETE 等.模式:'cors'，//无cors，*cors，同源缓存:'无缓存'，//*默认，无缓存，重新加载，强制缓存，仅当缓存标题:{'内容类型':'图像/jpeg'}})const blob = 等待 response.blob()返回 [URL.createObjectURL(blob), null];}捕捉(错误){console.error(`get: 发生错误 ${error}`);返回 [空，错误]}}函数 foo(props: any) {const [screenShot, setScreenshot] = useState(undefined)const url = props.urluseEffect(() => {异步函数 fetchData() {//你可以在这里等待const [响应，错误] = await get(url)如果(错误)日志(错误)别的 {日志(`得到响应 ${response}`)设置截图(响应)}}取数据()；}, [网址])返回 
<img src={screenShot} className=屏幕截图"alt=显示屏幕截图"；/>
}

I'm trying to fetch images from an express backend and display them in the react js frontend. How can I achieve this perfectly?

I have tried to fetch the images saved in my backend folder named "Backup" and display them back to the user in the react js frontend. I have tried this using axios but still am getting an invalid image instead of the correct image.

Below is my fetch request in the frontend.

fetchImages = () => {
    const imageName = 'garande.png'
    const url = `http://localhost:5000/fetchImage/${imageName}`
    axios.get(url, {responseType: 'blob'})
    .then(res => {
        return(
            <img src={res.data} alt="trial" />
        )
    }
}

And this what I have in the server.js file in the backend

app.get('/fetchImage/:file(*)', (req, res) => {
    let file = req.params.file;
    let fileLocation = path.join('../Backup/images/', file);
    //res.send({image: fileLocation});
    res.sendFile(`${fileLocation}`)
})

I expect the Image to show up in the users page. Thanks.

解决方案

This worked for me:

export async function get(url: string) {
    try {
        const response = await fetch(url, {
            method: 'GET', // *GET, POST, PUT, DELETE, etc.
            mode: 'cors', // no-cors, *cors, same-origin
            cache: 'no-cache', // *default, no-cache, reload, force-cache, only-if-cached
            headers: {
                'Content-Type': 'image/jpeg'
            }
        })
        const blob = await response.blob()
        return [URL.createObjectURL(blob), null];
    }
    catch (error) {
        console.error(`get: error occurred ${error}`);
        return [null, error]
    }
}   

function foo(props: any) {
const [screenShot, setScreenshot] = useState(undefined)
const url = props.url
useEffect(() => {
    async function fetchData() {
        // You can await here
        const [response, error] = await get(url)
        if (error)
            log(error)
        else {
            log(`got response ${response}`)
        setScreenshot(response)
        }
    }
    fetchData();
}, [url])

return <div>
    <img src={screenShot} className="Screenshot" alt="showing screen capture" />
</div>
}

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