在反应中传递状态或道具以将值传递给子组件

Question

I'm quite new to react. I need to pass whether validation is success or not to child react component.Below is my parent component.

Login.js - Parent

update = name => {
    this.setState({inputValidation:false})// or with es6 this.setState({name})
  }

  nextClick = () => {
    const {type, nicPassportNumber, accountNumner } = this.state;
    if(type === ''){ //TODO add validations here
      alert('please enter a value to proceed');
      this.inputValidation = true;
      this.update();
      console.log("afetr : ", this.inputValidation);
      return;
    }
    const code = type === 'nic-pass' ? nicPassportNumber : accountNumner;
    this.props.verifyNumber(code, type);
  };

  render() {
    const {nicPassportNumber, accountNumner} = this.state;
    return (
      <div className="container-fluid">
              <div className="row form-group">
                  <div className = "col-lg-10 col-xl-6 offset-xl-3 offset-lg-1">
                      <Input_Box label = "Enter NIC / Passport" value={nicPassportNumber} onChangeFunc={this.handleChange} valid = {this.state.inputValidation} type='nic-pass' {...this.props}/>
                      <h2 className="sc-txt-hor-center my-3">OR</h2>
                      <Input_Box label = "Enter mobile / DTV / Broadband number" value={accountNumner} onChangeFunc={this.handleChange} valid = {this.state.inputValidation} type='account' {...this.props}/>
                  </div>
              </div>
              <Footer onBackClick={this.backClick} onNextClick={this.nextClick}/>
      </div>
    );

Input_Box.js - Child component

constructor(props) {
        super(props);
    }


    render() {
        const {label, value, onChangeFunc, type} = this.props;
        console.log("Val input box : ", this.props.inputValidation);

        return (
            <div className="sc-input">
                <label className="sc-input__label mb-3" htmlFor="nic_passport_no">{label}</label>
                <input type="text" 
                    className="form-control sc-input__box" 
                    id="nic_passport_no" 
                    placeholder="" 
                    value={value} 
                    onChange={(e) => onChangeFunc(e, type)  }/>
                <label className="sc-input__error-msg">123214</label>
            </div>
        );
    }
}

I tried most of the suggestion given in SO. But every time I'm getting undefined for inputValidation in child component.

What I'm doing wrong here ?

Answer 1

This problem seems to be caused by incorrect props passed to <Input_Box/> :

{/* use inputValidation prop rather than valid prop */}
<Input_Box inputValidation={this.state.inputValidation} label="Enter NIC / Passport" value={nicPassportNumber} onChangeFunc={this.handleChange} type='nic-pass' {...this.props}/>

<h2 className="sc-txt-hor-center my-3">OR</h2>

{/* use inputValidation prop rather than valid prop */}
<Input_Box inputValidation={this.state.inputValidation} label="Enter mobile / DTV / Broadband number" value={accountNumner} onChangeFunc={this.handleChange}  type='account' {...this.props}/>

Also, the reason console is logging undefined seems to be because you're accessing inputValidation from the component instance this rather than the state of the component:

// console.log("afetr : ", this.inputValidation); 
console.log("after : ", this.state.inputValidation);

Hope this helps!