Update array of object in React Js

Question

I want to update question name on onChange event. But problem is every question changes if I change only one ques.How to fix it ?

class QuestionCreate extends React.Component {
    constructor(props){
        super(props);
        this.state = {
            datas: [],
            default_question: {
                isNew: true,
                question: {
                    name: 'Click to write the question text',
                    answer_options: [
                        {name: 'click to write choice 1', 'choice': true},
                        {name: 'click to write choice 1', 'choice': true},
                        {name: 'click to write choice 1', 'choice': true},
                    ]
                }
            }
        }

    }


    onChangeQuestion(qustions, index, event){
        let all_data = this.state.datas;
        let currentQuestion = all_data[index].question
        all_data[index]['question']['name'] = event.target.value;
        console.log(all_data[index]['question']['name'])
        this.setState({datas: all_data})

    }

    displayRow(){
    let rowData = this.state.datas.map( (data, index) =>{
        console.log("this is data:", data, index);
        return(
            <div className="well" key={ index }>
                <h3>Q. <input type="text" onChange={ this.onChangeQuestion.bind(this, data, index) } value={ data.question.name } /></h3>
                    <ul>
                        <li>option</li>
                    </ul>
            </div>
        )
    })

    return rowData;
}

Please post your initial data and what data you are getting after operation. — Niladri Basu
– Niladri Basu, Commented Oct 24, 2017 at 4:51

anand · Accepted Answer · 2017-10-24 06:52:00Z

2

You are mutating your state directly.

let all_data = this.state.datas;
let currentQuestion = all_data[index].question
all_data[index]['question']['name'] = event.target.value;

Use:

let all_data = JSON.parse(JSON.stringify(this.state.datas));
let currentQuestion = all_data[index].question;
all_data[index]['question']['name'] = event.target.value;
this.setState({datas: all_data});

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edited Oct 24, 2017 at 6:52

answered Oct 24, 2017 at 4:54

anand

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10 Comments

anand Over a year ago

You are changing this.state by using the above statements. This is not good. You can read reactjs.org/tutorial/… to better understand the issue.

anand Over a year ago

Do ask if you still have any doubts

Shaon shaonty Over a year ago

onChangeQuestion(qustions, index, event){ let all_data = this.state.datas; let currentQuestion = all_data[index].question let newQues = Object.assign({}, currentQuestion, {name:event.target.value}) this.setState({ datas: all_data }) }

Shaon shaonty Over a year ago

is there need this line ? this.setState({ datas: all_data })

anand Over a year ago

in the line let all_data = this.state.datas;, you are assigning a reference to this.state.datas. So when you change all_data, you change this.state. In order to avoid that, you can do let all_data = JSON.parse(JSON.stringify(this.state.datas)); to create a copy of this.state.datas.

|

Shaon shaonty · Accepted Answer · 2017-10-24 06:40:14Z

0

it is working after editing onChangeQuestion function.

onChangeQuestion(qustions, index, event){
    let all_data = JSON.parse(JSON.stringify(this.state.datas)); 
    let currentQuestion = all_data[index].question 
    all_data[index]['question']['name'] = event.target.value; 
    this.setState({datas: all_data});
}

answered Oct 24, 2017 at 6:40

Shaon shaonty

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