Vishnu Paspunoor Vishnu Paspunoor - 1 month ago 7
React JSX Question

Using for loops and switch cases in React to dynamically render different components

I am trying to render components conditionally using switch case in React JSX. I am trying to build something that reads from a specific json structure and renders the data. Since there can be many different components and data, I am trying to render it dynamically. See my code below, I am not getting any errors but the components aren't getting rendered. Inside my html , I can only see . This means the loop isn't working. I tried using the same loop in vanilla JS and it works.

var myPackage = [{
sectionInfo:[{
elementType: 1,
text: "This is text from element type 1"
}]
},
{
sectionInfo:[{
elementType: 2,
text: "This is text from element type 2"
}]
}];
var App = React.createClass({

render: function(){
var elements = [];
elements = myPackage.map(function(myObj){
myObj.sectionInfo.map(function(myObj1){
switch(myObj1.elementType){
case 1: return(
<Component1 text = {myObj1.text}/>
);
break;
case 2: return(
<Component2 text = {myObj1.text}/>
)
break;
}
})
});
return(
<div className="App">
{elements}
</div>
)
}
});
var Component1 = React.createClass({
render:function(){
return(
<div className = "element1">
{this.props.text}
</div>
)
}
});
var Component2 = React.createClass({
render:function(){
return(
<div className = "element2">
{this.props.text}
</div>
)
}
});
ReactDOM.render(<App/>,document.getElementById('container'));


Edit: Made a few additions to the code, and now I am facing a new problem. Here is the new code:

var App = React.createClass({

render: function(){
var elements = [];
elements = myPackage.map(function(myObj){
return(
<div>
myObj.sectionInfo.map(function(myObj1){
switch(myObj1.elementType){
case 1: return(
<Component1 text = {myObj1.text}/>
);
break;
case 2: return(
<Component2 text = {myObj1.text}/>
)
break;
}
}
</div>
)
});
return(
<div className="App">
{elements}
</div>
)
}
});


I want to render each time inside a div. So that if one section has more than 3 elements, then all 3 must be inside a div.

Answer

You should return value from first .map, in your case it is result from inner .map

var elements = myPackage.map(function(myObj){
  return myObj.sectionInfo.map(function(myObj1) {
     // ...  
  });
});

Update:

Based on your new update, you can change your code like this

var App = React.createClass({

  section: function(myObj, parentIndex) {
    return myObj.sectionInfo.map(function(myObj1, index) {
      const key = parentIndex + '.' + index;

      switch(myObj1.elementType) {
        case 1:
          return <Component1 text = {myObj1.text} key={ key } />
        case 2:
          return <Component2 text = {myObj1.text} key={ key } />
      }
    });
  },

  render: function() {
    var elements = myPackage.map(function(myObj) {
      return <div>
        { this.section(myObj, index) }
      </div>
    }, this);

    return <div className="App">
     { elements }
    </div>;
  }
});
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