CODEWITHSUNDEEP
javascriptreactjscomponentsparent-childstateless
Hyperspace
Hyperspace

Reputation: 75

react stateless child components do not update on state change in parent component

I'm building a small tabbed application in which each tab renders a child component.

I wanted each tab to display different content so I created an object contentTypes outside render(){ .... } to map each tab to it's corresponding child component. The child components receive handlers and states via props.

class App extends Component {
    state ={
        contentType: "A",
        title: "Overview",
        searchContent: ""
    }

    tabHandler= (content,event)=>{
       console.log("clicked");
       this.setState({
          title: event.target.name,
          contentType: content
       });
    }
    searchHandler = (event) => {

       // this performs a search on a database and 
       //returns suggestions for the current input

       this.setState({
          searchContent: event.target.value
       });
   }  

    contentTypes = {
        A: <A/>,
        B: <B/>,
        C: <C onchange={this.searchHandler.bind(this)} content={this.state.searchContent}/>
    };
    render() {
      return (
        <div className="row">
          <ul>
           <Tab click={this.tabHandler.bind(this)} id="A" name="A"/>
           <Tab click={this.tabHandler.bind(this)} id="B" name="B"/>
           <Tab click={this.tabHandler.bind(this)} id="C" name="C"/>
         </ul>
        <h1 id="title">{this.state.title}</h1>

        {this.contentTypes[this.state.contentType]}

       </div>
     );
   }
}

The child components are stateless, defined somewhat like this:

import React from 'react'
import Field from './form-builder/field';

const C = (props) => {

return(

    // Field is another stateless component with formatted <input> tags

    <Field type="text" name="search" content={props.content} onchange={props.onchange}/>
  );
 }

export default C;

Field is defined as follows:

import React from 'react';

const field = (props) => {
    <li className="field">
       <input type="text" onChange={props.onchange} value={props.content} />
       <label htmlFor={props.name}>{props.value}</label>
    </li>
}
export default field;

The problem is that when I call a handler from inside Field to update the state in a parent component, (the one with render(){ .... }) The child components don't update with the new state.

Any ideas on how to fix this?

Upvotes: 3

Views: 1506

Answers (1)

DanSnow
DanSnow

Reputation: 121

You define contentTypes as class property.
It's actually same as:

class App extends Component {
  constructor() {
    this.contentTypes = {
      A: <A />,
      B: <B />,
      C: <C
           onchange={this.searchHandler.bind(this)}
           content={this.state.searchContent}/>
    }
  }
}

So the element rendered in the constructor and never get any update of props.
Here is a way to fix this:

class App extends Component {
  contentTypes = {
    A: () => (<A/>),
    B: () => (<B/>),
    C: () => (
        <C
          onchange={this.searchHandler.bind(this)}
          content={this.state.searchContent} />
       )
  }

  // ...

  render () {
    const Content = this.contentTypes[this.state.contentType]

    return (
      <div>
      {/* ... */}
        <Content />
      </div>
    )
  }
}

Upvotes: 1

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