函数在反应中被多次调用

Question

I would like to know why the function gets called multiple times wheh dispatch. Also, is there any better way to do,

getData = (value) =>{
  const body = {
    value: value,
    cn: "TH"
  }
return body;
}

renderData(){
  console.log("starts");
  this.props.dispatch(queryData(this.getData(10)));// called repeatedly 
}

render(){
  return(
   <div>{this.renderData()}</div>
  ) 
}

I have updated the different scenario by same type, I need to know is there any other better way to.

scenario 2

getData = () =>{
  const body = {
    value: value,
    cn: "TH"
  }
return body;
}
componentDidMount=()=>{
  this.props.dispatch(queryData(this.getData()))
}
componentDidUpdate = () => {
const {allstate} = this.props.querydata 
  if(this.props.querydata){
    this.renderState(allstate);
  }
}
renderState = (data) => {
  const getId = data.map(e=>e.id); //will get array of values [2, 3, 4]
  getid.map(e=>
    this.props.dispatch(queryState(e))); //for every id dispatch props, 
  )
}
render(){
  // will gets this by componentDidMount call
  return (
    <div>

   </div>
  )
}

Answer 1

When there is render in view , renderData function gets called which dispatch some action, and again this make your component re-render. One solution can be move your this.renderData() function outside the render , may be in constructor or componentDidMount

Answer 2

render function will be called every time React class get updated.

If your action queryData is for fetching data to display in component, put it inside componentDidMount . It will only be called once when React component first mounted.