如何在ReactJS中使用Object.key.map（）？

Question

I am studying ReactJS, and making a website with it and Firebase.

I wanted to display all images in my Firebase Stroage, but I don't know how to do that, and my code does't work.

I got the all url of images in Firebase Storage, and put these into array. when I console.log(imageObejct), it shows all links correctly.

But my render (object.key.map) doesn't work.

I tried different ways, but didn't work.

Help!

I have tried 1. https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/map#Description

2. https://flaviocopes.com/react-how-to-loop/

class ImageUpload extends React.Component {
    constructor(props) {
        super(props);
        this.state = {
            image: [],
            user: this.props.user,
            url: '',
            progress: 0,
            dialog: false,
            fileName: '',
            file: '',
            imagePreviewUrl: '',
            title: '',
            content: '',
            imagePath: [],
            imageObject: ''
        };

////////////////////////////////////////////////////////
 displayImage = (images) => {

        // Get the download URL

        images.getDownloadURL().then(data => {
            // Insert url into an <img> tag to "download"
            this.setState({ imageObject : [(this.state.imageObject == null) ? null : data] })

           // console.log(this.state.imageObject)
        }).catch(error => {
//////////////////////////////////////////
    render() {
        const { classes } = this.props;
        return (
             <div>
                {Object.keys(this.state.imageObject).map(id => {
                    const img = this.state.imageObject[id];
                    return (
                        <Card key={id}>
                            <CardContent>
                                <Typography>
                                    Title: 
             ///here!!//              <img src={img}/>
                                </Typography>

I expected all images in my Firebase Storage

but it just shows me only one(first one) image out of 12.

Answer 1

Firstly set your imageObject to empty array as default, if it is an array (probably it'd be named imageArray then):

 this.state = {
   imageObject: []
 };

Then in your setState , add the data to your array

 images.getDownloadURL().then(data => {
   this.setState(state => ({
     imageObject: [...state.imageObject, data]
   }))
 })

After that when you render it, you don't need to use Object.keys , but just map the array:

 return (
    <div>
    {this.state.imageObject.map(img => {
     return (
//...