Promise Error: Objects are not valid as a React child

Question

I am trying to set the json to a state using user agent, I get the error:

Uncaught Invariant Violation: Objects are not valid as a React child (found: object with keys {...}). If you meant to render a collection of children, use an array instead or wrap the object using createFragment(object) from the React add-ons.

method to set state:

 getInitialState: function(){
    return {
        arrayFromJson: []
    }
},

loadAssessmentContacts: function() {
    var callback = function(data) {
        this.setState({arrayFromJson: data.schools})
    }.bind(this);

    service.getSchools(callback);
},

componentWillMount: function(){
    this.loadAssessmentContacts();
},

onTableUpdate: function(data){

    console.log(data);

},

render: function() {

    return (
        <span>{this.state.arrayFromJson}</span>
    );
}

service

getSchools : function (callback) {
        var url = 'file.json';
       request
            .get(url)
            .set('Accept', 'application/json')
            .end(function (err, res) {
                if (res && res.ok) {
                    var data = res.body;
                    callback(data);

                } else {
                    console.warn('Failed to load.');
                }
            });
    }

Json

{
"schools": [
{
  "id": 4281,
  "name": "t",
  "dfe": "t",
  "la": 227,
  "telephone": "t",
  "address": "t",
  "address2": "t",
  "address3": "t",
  "postCode": "t",
  "county": "t",
  "ofsted": "t",
  "students": 2,
  "activeStudents": 2,
  "inActiveStudents": 0,
  "lastUpdatedInDays": 0,
  "deInstalled": false,
  "inLa": false,
  "status": "unnassigned",
  "authCode": "t",
  "studentsActivity": 0
},......
]}

Answer 1

You can't do this: {this.state.arrayFromJson} As your error suggests what you are trying to do is not valid. You are trying to render the whole array as a React child. This is not valid. You should iterate through the array and render each element. I use .map to do that.

I am pasting a link from where you can learn how to render elements from an array with React.

http://jasonjl.me/blog/2015/04/18/rendering-list-of-elements-in-react-with-jsx/

Hope it helps!

Answer 2

You can't just return an array of objects because there's nothing telling React how to render that. You'll need to return an array of components or elements like:

render: function() {
  return (
    <span>
      // This will go through all the elements in arrayFromJson and
      // render each one as a <SomeComponent /> with data from the object
      {this.state.arrayFromJson.map(function(object) {
        return (
          <SomeComponent key={object.id} data={object} />
        );
      })}
    </span>
  );
}