React Native, construct initial state values from a object or array

Question

Is it possible to create states in the constructor passed to that component from an array or object.

Here is what is to be achieved:

constructor(props) {
    super(props);
    this.state= {
        Object.keys(this.props.data).map((key, i) => {
            [key]: 'boo',
        })
    }
}

but it returns a syntax error.

The idea is that the data within this.props.data creates a series of states. The data passed to this.props.data is not known by the component in advance but is passed to it as a prop when the component is used.

prasanth · Accepted Answer · 2020-03-21 06:44:13Z

2

You could directly declare this.state with return array of map

updated

constructor(props) {
    super(props);
    this.mapData = Object.keys(this.props.data).map((key, i) =>({[key]: 'boo'}))
    this.state = this.pre_state ? Object.assign({}, ...this.pre_state) : {};
}

edited Mar 21, 2020 at 6:44

answered Mar 19, 2020 at 17:24

prasanth

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2 Comments

Walrus Over a year ago

However, the state is not accessible. Calling this.state.WhateverTheKeyWas returns as undefined.

prasanth Over a year ago

Sorry . this.state only accept as object . i just updated my answer .You could use Object.assign for creating array to object .sample eg codesandbox.io/s/staging-cdn-pr6td

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