How to update an array in react using prevState?

Question

I want to insert a record into the array.

I found an information that should not be used to push for state preservation measure.

this.state = {
            dados : {
                doc: '',
                infe: '',
                bene: '',
                inco: [],
                cino: [],
            }
        }

this.setState(prevState => ({ dados:{
                inco: [...prevState.dados.inco, URL.createObjectURL(result)]
            }}))

this.setState(prevState => ({ dados:{
                cino: [...prevState.dados.cino, URL.createObjectURL(result)]
            }}))

Is result variable appropriate? Plus i think your dados state variable is getting overwritten in first setstate function — mindaJalaj
– mindaJalaj, Commented Apr 29, 2018 at 7:10

mindaJalaj · Accepted Answer · 2018-04-29 07:15:57Z

3

Try to club the setstate() function call into one, as dados state key might lose other properties, hence it cannot find cino object in second setstate(). Here dados state object was getting only inco property after first setState() function call, hence now below code we are making sure consistency in state object is maintained

Here is sample code

 this.state = {
            dados : {
                doc: '',
                infe: '',
                bene: '',
                inco: [],
                cino: [],
            }
        }

this.setState(prevState => (
                 { 
                    dados:{
                            ...prevState.dados,
                            inco: [...prevState.dados.inco,
                                    URL.createObjectURL(result)
                                  ],
                            cino: [...prevState.dados.cino,
                                    URL.createObjectURL(result)
                                  ]
            }}))

answered Apr 29, 2018 at 7:15

mindaJalaj

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1 Comment

marcelo.delta Over a year ago

Its Work. Thank You Very Much!

Vaibhav · Accepted Answer · 2019-07-04 05:20:46Z

0

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                 name:name,
                 question:question,
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edited Jul 4, 2019 at 5:20

Vaibhav

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answered Jul 4, 2019 at 4:08

Prathamesh Sawant

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