如何在React Native中获取对象数组中的对象

Question

I'm kind of lost to access some info in my static data. Here's the data :

{
 "info1": {
    "label": "label",
    "class": "class-css",
    "title": "title",
    "text": "text",
    "number": "20",
    "tags": [
         {
            "name": "#twitter"
        },
        {
            "name": "#myspace"
        }
    ]
 },
 "info2": {
    "label": "label",
    "class": "class-css",
    "title": "title",
    "text": "text",
    "number": "20",
    "tags": [
         {
            "name": "#instagram"
        },
        {
            "name": "#facebook"
        }
    ]
  }
}

Then I get the first info like that :

this.setState({
    currentLabel: this.state.labels["info1"]
})

This is why I want and then I want to display info in a component and it's working until I try to get tags information. I tried a .map() but without success and error.

<View>
   <Text>{infoDetail.title}</Text>
   <Text>{infoDetail.text}</Text>
   <Text>How do I get "tags" information</Text>
</View>

Is it possible to access these objects in the array "tags" ?

Answer 1

yes you can call tags as follows infoDetail.tags and do map on it

render(){
      const tagItems = infoDetail && infoDetail.tags.map((item, index) => {
          return <Text key={index}>{item.name}</Text>
      });
      return(
        <View>
          <Text>{infoDetail.title}</Text>
          <Text>{infoDetail.text}</Text>
          {tagItems}
        </View>
      )
}

Answer 2

Probably something like this. <Text>{infoDetail.tags.map(tag => {/*render */})}</Text>

Answer 3

You can try Object.keys() and Array.prototype.reduce() to get your favorite data:

 const data = { "info1": { "label": "label", "class": "class-css", "title": "title", "text": "text", "number": "20", "tags": [ { "name": "#twitter" }, { "name": "#myspace" } ] }, "info2": { "label": "label", "class": "class-css", "title": "title", "text": "text", "number": "20", "tags": [ { "name": "#instagram" }, { "name": "#facebook" } ] } }; const tags = Object.keys(data).reduce((result, key) => { return result.concat(data[key].tags); }, []) console.log(tags); /* tags = [ { "name": "#twitter" }, { "name": "#myspace" }, { "name": "#instagram" }, { "name": "#facebook" } ] */ 

Answer 4

Here is a full working code. Since your labels state property is an object, you need to map it somehow. I've chosen Object.values here. You can use Object.keys or even Object.entries according to your needs.

I've used a separate Info component and passed the values to it, then render there. In this component, we are again mapping the tags , then rendering the list.

 class App extends React.Component { state = { labels: { info1: { label: "label1", class: "class-css", title: "title", text: "text", number: "20", tags: [ { name: "#twitter", }, { name: "#myspace", }, ], }, info2: { label: "label2", class: "class-css", title: "title", text: "text", number: "20", tags: [ { name: "#instagram", }, { name: "#facebook", }, ], }, }, } render() { const { labels } = this.state; return ( <div> { Object.values( labels ).map( value => <Info label={value} key={value.label} /> ) } </div> ); } } const Info = ( props ) => { const { title, text, tags } = props.label; const tagList = tags.map( tag => <p key={tag.name}>{tag.name}</p> ); return ( <div style={{ border: "1px solid gray", marginTop: "-1px" }}> <p>{title}</p> <p>{text}</p> <div>{tagList}</div> </div> ); }; ReactDOM.render( <App />, document.getElementById("root") ); 

 <script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.1.0/react.min.js"></script> <script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.1.0/react-dom.min.js"></script> <div id="root"></div> 

Update

If your data is totally static then @Xavi A.'s method is a good option. I don't know how is your list but I provide a simple code including something like you want here.

 const labels = { info1: { label: "label1", class: "class-css", title: "title", text: "text", number: "20", tags: [ { name: "#twitter" }, { name: "#myspace" } ] }, info2: { label: "label2", class: "class-css", title: "title", text: "text", number: "20", tags: [ { name: "#instagram" }, { name: "#facebook" } ] } }; class App extends React.Component { state = { currentLabel: Object.keys(labels)[0] }; handleInfoChange = info => this.setState({ currentLabel: info }); renderList = () => ( <ul> {Object.keys(labels).map(info => ( <Item key={info} info={info} onClick={this.handleInfoChange} /> ))} </ul> ); render() { const { currentLabel } = this.state; return ( <div> {this.renderList()} <Info currentLabel={currentLabel} /> </div> ); } } const Item = props => { const { info, onClick } = props; const handleClick = () => onClick(info); return <li onClick={handleClick}>{info}</li>; }; const Info = props => { const { currentLabel } = props; const { title, text, tags } = labels[currentLabel]; const tagList = tags.map(tag => <p key={tag.name}>{tag.name}</p>); return ( <div style={{ border: "1px solid gray", marginTop: "-1px" }}> <p>{title}</p> <p>{text}</p> <div>{tagList}</div> </div> ); }; ReactDOM.render( <App />, document.getElementById( "root" ) ); 

 <script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.1.0/react.min.js"></script> <script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.1.0/react-dom.min.js"></script> <div id="root"></div> 

Answer 5

No need to save all the static data in your state, you can keep your state cleaner by just saving the selected label:

onLabelSelect = label => {
    //label will be "info1" for example
    this.setState({
        currentLabel: label 
    })
}

Then in your render:

render(){ 
    //get infoDetail from staticData 
    const infoDetail = staticData[this.state.currentLabel]         
    return (
        <View>
            <Text>{infoDetail.title}</Text>
            <Text>{infoDetail.text}</Text>
            {infoDetail.tags.map( ({name}) => <Text>name</Text>)}
        </View>
    )
}

Note about the map. This:

{infoDetail.tags.map( ({name}) => <Text>name</Text>)}

is a shorter version of:

{infoDetail.tags.map( item => {
    return <Text>item.name</Text>
})}