Change the focus automatically to the next TextInput in react native

Question

I am developing an App with react native. I have three TextInput boxes as bellow:

I need to change the focus of the TextInput box automatically, if the user inserts a number. Then, as soon as he/she inserts the last number a function should be executed.

Here is my code:

  <View style={styles.squareContainer}>
                <View style={styles.square}>
                    <TextInput
                      onChangeText={(oldPassword) => this.setState({oldPassword})}
                      style={{flex:1}}
                      ref="1"
                      keyboardType={'numeric'}
                      style={styles.inputText}
                      maxLength = {1}
                      underlineColorAndroid='rgba(0,0,0,0)'
                      numberOfLines={1}
                      secureTextEntry={true}
                      onSubmitEditing={() => this.focusNextField('2')}


                    />
                </View>
                <View style={styles.square}>
                    <TextInput
                      style={{flex:1}}
                      ref="2"
                      onChangeText={(oldPassword) => this.setState({oldPassword})}
                      keyboardType={'numeric'}
                      maxLength = {1}
                      style={styles.inputText}
                      underlineColorAndroid='rgba(0,0,0,0)'
                      numberOfLines={1}
                      secureTextEntry={true}
                      onSubmitEditing={this.maxLength?1:() => this.focusNextField('3')}


                    />
                </View>
                <View style={styles.square}>
                    <TextInput
                      style={{flex:1}}
                      ref="3"
                      onChangeText={(oldPassword) => this.setState({oldPassword})}
                      returnKeyType='next'
                      keyboardType={'numeric'}
                      style={styles.inputText}
                      underlineColorAndroid='rgba(0,0,0,0)'
                      numberOfLines={1}
                      secureTextEntry={true}


                    />
                </View>
              </View>

In other words, for example if a user wants to insert 153, he/she should insert 1 into the first TextInput, then the curser and focus should replace to the next TextInput automatically and she/he can inserts 5 and finally by moving the focus and curser to the third TextInput, he/she can inserts 3. As soon as he inserts 3, I need to execute this.triggerFunction(). I tried to use the following trick as you can see, but it did't work:

onSubmitEditing={this.maxLength?1:() => this.focusNextField('3')}

Can you help me to solve this problem. Thanks in advance.

Answer 1

You have to focus the TextInput you want the cursor to go to. To do that, You can set maxLength to 1, and call onChangeText to change focus. You may also want to capture the value and store it in state.

Another thing you should is to use words or characters for your references. These are going to be called as objects and numbers may be a bit confusing to call. i.e ref={'input_1'} instead of ref={'1'}

 <TextInput
    style={{flex:1}}
    ref="input_1"
    keyboardType={'numeric'}
    style={styles.inputText}
    maxLength = {1}
    value={this.state.value}
    underlineColorAndroid='rgba(0,0,0,0)'
    numberOfLines={1}
    secureTextEntry={true}
    onChangeText={value => {
       this.setState({ value })
       if (value) this.refs.input_2.focus(); //assumption is TextInput ref is input_2
    }}
  />

Answer 2

The answered question was definitely beneficial but my es-lint was throwing an error saying use of strings or maybe this.refs is depreciated

So this is what I did, create refs in the constructor (probably this is how react suggests). In my cases, I wanted 4 Text Inputs boxes

constructor(props) {
        super(props)
        this.keyboardHeight = new Animated.Value(0)
        this.num1 = React.createRef()
        this.num2 = React.createRef()
        this.num3 = React.createRef()
        this.num4 = React.createRef()
    }

And then render component like this

<View style={styles.inputBoxes}>
                        <TextInput
                            ref={this.num1}
                            style={styles.textInput}
                            onChangeText={number => this.inputNumber(number, 1)}
                            value={this.state.num1}
                            keyboardType="numeric"
                            numberOfLines={1}
                        />
                        <TextInput
                            ref={this.num2}
                            style={styles.textInput}
                            onChangeText={number => this.inputNumber(number, 2)}
                            value={this.state.num2}
                            keyboardType="numeric"
                            numberOfLines={1}
                        />
                        <TextInput
                            ref={this.num3}
                            style={styles.textInput}
                            onChangeText={number => this.inputNumber(number, 3)}
                            value={this.state.num3}
                            keyboardType="numeric"
                            numberOfLines={1}
                        />
                        <TextInput
                            ref={this.num4}
                            style={styles.textInput}
                            onChangeText={number => this.inputNumber(number, 4)}
                            value={this.state.num4}
                            keyboardType="numeric"
                            numberOfLines={1}
                        />
                    </View>

notice the refs here inside TextInput. In my onChange, I am passing a flag, telling which button it is to this.inputNumber

And this is how my inputNumber function looks like

inputNumber(value, flag) {
    const completeFlag = `num${flag}`
    this.setState({[completeFlag]: value})
    flag = flag + 1
    if (flag < 5 && value) {
        const nextFlag = `num${flag}`
        const textInputToFocus = this[nextFlag]
        textInputToFocus.current.focus()
    }
}