Respond to a unique key

Question

I know that there are many answers to this problem, but I could not find the one that exactly solved my problem. I get the following error:Warning: Each child in an array or iterator should have a unique "key" prop. Check the render method of QuestionItem. See https://fb.me/react-warning-keys for more information.

I set the key for the component, but I can not get the warning to go away.

The main component:

renderData() {
        return this.state.data.map((data) => {
            return (
                <QuestionItem key={data._id} data={data} delete={this.deleteItem} edit={this.editItem} />
            )
        })
    }

QuestionItem element:

import React, { Component, PropTypes } from 'react';
import Card from 'material-ui/lib/card/card';
import CardActions from 'material-ui/lib/card/card-actions';
import CardHeader from 'material-ui/lib/card/card-header';
import CardMedia from 'material-ui/lib/card/card-media';
import CardTitle from 'material-ui/lib/card/card-title';
import FlatButton from 'material-ui/lib/flat-button';
import CardText from 'material-ui/lib/card/card-text';
import Delete from 'material-ui/lib/svg-icons/action/delete';
import ModeEdit from 'material-ui/lib/svg-icons/editor/mode-edit';
import IconButton from 'material-ui/lib/icon-button';
import Button from '../UI/Button';

class QuestionItem extends Component {

    renderTags() {
        return this.props.data.tag.map((tag) => {
            return (
                <FlatButton label={tag} />
            )
        })
    }

    renderCompany() {
        return this.props.data.company.map((company) => {
            return (
                <FlatButton label={company} />
            )
        })
    }

    edit = () => {
        this.props.edit(this.props.data);
    }

    delete = () => {
        this.props.delete(this.props.data._id);
        console.log(this.props.data._id);
    }

    render() {
        return (
            <Card style={{margin: 50}}>
                <CardTitle title={this.props.data.text} />
                <CardText>
                    {this.props.data.answer}
                </CardText>
                <CardActions>
                    { this.renderTags() }
                    { this.renderCompany() }

                    <IconButton onClick={this.delete} style={{float: 'right'}}>
                        <Delete />
                    </IconButton>
                    <IconButton onClick={this.edit} style={{float: 'right'}}>
                        <ModeEdit />
                    </IconButton>
                </CardActions>
            </Card>
        )
    }
}

export default QuestionItem;

What am I missing here?

Answer 1

Well, you need to get out data._idand make sure they are all unique. Or you can do this:

renderData() {
  return this.state.data.map((data, index) => {
    return (
      <QuestionItem key={index} data={data} delete={this.deleteItem} edit-{this.editItem} />
    );
 });
}

As another answer pointed out, another one calls map, which goes to the need for rendering to set the character keyto a unique value too.

So these:

renderTags() {
    return this.props.data.tag.map((tag) => {
        return (
            <FlatButton label={tag} />
        )
    })
}

renderCompany() {
    return this.props.data.company.map((company) => {
        return (
            <FlatButton label={company} />
        )
    })
}

It should become:

renderTags() {
    return this.props.data.tag.map((tag, index) => {
        return (
            <FlatButton key={index} label={tag} />
        );
    });
}

renderCompany() {
    return this.props.data.company.map((company, index) => {
        return (
            <FlatButton key={index} label={company} />
        );
    });
}

, index, . SQL. , ! , key - . key :

- :

key : string | boolean | number | null,

, ( , , , , ), :

renderTags() {
    return this.props.data.tag.map((tag) => {
        return (
            <FlatButton key={tag} label={tag} />
        );
    });
}

- (tag || '').toLowerCase().replace(' ', '_'), , React - ( ). ! DOM, data-reactid, , ( , 0.15 ). React 0,15.

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Answer 2

renderTags() renderCompany() .