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javascriptreactjsasynchronouspromisees6-promise

How to setState array of objects in component?


I fetch a list of files from backend and push it to the array of objects (dirloc) in component state. At the moment console log shows multiple logs of dirloc for each file. I want to setState once everything is pushed to the dirloc. How to do it?

    class Load extends Component {
      constructor({ props, token }) {
        super(props, token);
        this.state = {
          nodeRes: [],
          dirloc: []
        };
      }

      componentDidMount() {
        fetch("http://192.168.22.124:3000/loadit/", {
          headers: new Headers({
            authorization: `Bearer ${this.props.token}`,
            "Content-Type": "application/json"
          })
        })
          .then(response => response.json())
          .then(logit => {
            let { dirloc, nodeRes } = this.state;
            logit.map(verifypath => {
              let getpath = verifypath.substring(0, verifypath.lastIndexOf("/"));
              let dirnames = getpath
                .toString()
                .split("/")
                .pop();
              return getpath !== ""
                ? (dirloc.push({
                    getpath: getpath /* for e.g '/folder/of/files/' */,
                    dirnames: dirnames /* array of folder names */,
                    ffiles: verifypath /* full path '/folder/of/files/abc.jpg' */
                  }),
                  this.setState({ dirloc }, () => {
                    console.log(this.state.dirloc);
                  }))
                : (nodeRes.push(verifypath), this.setState({ nodeRes }));
            });
          })
          .then(getdata => this.allFetch(this.state.nodeRes));
      }

    }

    render() {
    const {  dirloc } = this.state;
    let folderView;
    for (var i = 0; i < dirloc.length; i++) {
     if (Object.entries(dirloc).length !== 0 && dirloc.constructor !== Object) {
       folderView = <Filetree fileloc={this.state.dirloc} token={this.props.token} />
    console.log(`dirs: ${dirloc[i].getpath}`)
    } else {
        folderView = null
    }
  }

Edit: The problem is that when I render with conditional statement, I see that console log shows object multiple times which means it renders child component multiple times. I want to render it once only with all the required objects.


Solution

  • Generate the required values first and then invoke setState once at the end.

    fetch('http://192.168.22.124:3000/loadit/', {
      headers: new Headers({
        authorization: `Bearer ${this.props.token}`,
        'Content-Type': 'application/json',
      }),
    })
      .then((response) => response.json())
      .then((logit) => {
        const { dirloc, nodeRes } = this.state;
        const newDirLoc = [];
        const newNodeRes = [];
        logit.forEach((verifypath) => {
          const getpath = verifypath.substring(0, verifypath.lastIndexOf('/'));
          const dirnames = getpath.toString().split('/').pop();
          getpath !== ''
            ? newDirLoc.push({
              getpath,
              dirnames,
              ffiles: verifypath,
            })
            : newNodeRes.push(verifypath);
        });
        this.setState({
          nodeRes: [...nodeRes, ...newNodeRes],
          dirloc: [...dirloc, ...newDirLoc]
        })
      });
    

    At the render, check for the condition before the loop.

    render() {
      const { dirloc } = this.state;
      let folderView;
      if (dirloc.length) {
        for (let i = 0; i < dirloc.length; i++) {
          folderView = <Filetree fileloc={this.state.dirloc} token={this.props.token} />;
          console.log(`dirs: ${dirloc[i].getpath}`);
        }
      } else {
        folderView = null;
      }
    }
    

    Have replaced Object.entries with a simple length check as dirloc is an array.