如何填充另一个下拉列表

Question

我写了以下组件来生成两个下拉框，其中dllProducts依赖于ddlCategories，但问题是当将选定的产品类别值传递给函数（）getDataById它不会收到，所以我删除了代码。在功能ddlPordCatsChanegeEvent()我已添加评论。这是调用函数getDataById()正确的地方，如果没有什么是做的正确的方式产生ddlProducts

var gdata=[]; 

var trStyle = { 
    'color': 'black', 
    'border-style' :'solid', 
    'margin-left':'20%' 
}; 

var TWODROPDOWNCOMP = React.createClass({ 
    getInitialState:function(){ 
    return{data1:[], data2:[], isMounted:false, selectedValue:0} 
}, 
componentDidMount:function(){ 
    this.getData(); 
    this.setState({isMounted:true}) 
}, 
ddlProdCatsChanegeEvent: function(e) { 

    if (this.state.isMounted) 
    { 
     var newV = ReactDOM.findDOMNode(this.refs.refProdCats).value; 
     var seleValue = newV; 

     this.setState({selectedValue:newV}, function(){ 
      alert(this.state.selectedValue); 

      //HOW DO I POPULATE THE OTHER DROPDOWN WITH ID ddlProducts using the child component PRODOPTIONS 
     }); 

    } 
}, 
render: function() { 
    var prodCats = this.state.data1.map(function(ele, index){ 
     return <PRODCATSOPTION optValue={ele.ProductCategoryID} optText={ele.Name} /> 
    }); 

    prodCats.unshift(<PRODCATSOPTION optValue={''} optText={'--- select category ----'} />) 

    return (<div>Prodcut Category:<br /><select id="ddlCategories" ref="refProdCats" onChange={this.ddlProdCatsChanegeEvent}>{prodCats}</select><br /> 
     Products:<br /><select id="ddlPorducts" ref="refProds"></select><br /></div> 
    ) 
}, 
getDataById:function(catId){ 
    var x = catId; 
    alert('rec id:'+x); 

    $.ajax({ 
     url:'http://localhost:33401/Home/GetProductCats?id='+ x, 
     method:'GET', 
     success:function(d1){ 
      this.setState({data2:d1}); 
     }.bind(this), 
     error:function(){ 
      alert('ERROR'); 
     }.bind(this) 
    }) 
}, 
getData:function(){ 
    //ajax here 
    $.ajax({ 
     url:'http://localhost:33401/Home/GetProductCats', 
     method:'GET', 
     success:function(d1){ 
      this.setState({data1:d1}); 
     }.bind(this), 
     error:function(){ 
      alert('ERROR'); 
     }.bind(this) 
    }) 
} 
}); 

var PRODOPTIONS = React.createClass({ 
    render:function(){ 
     return(<option value={this.props.optValue}>{this.props.optText}</option>) 
    } 

}); 

var PRODCATSOPTION = React.createClass({ 
    render:function(){ 
     return(<option value={this.props.optValue}>{this.props.optText}</option>) 
    } 

}); 




ReactDOM.render(<TWODROPDOWNCOMP/>, document.getElementById('d1')); 

Answer 1

，你通常会做的选择应填充。在AJAX调用之后，选项出现了。

<select id="ddlPorducts" ref="refProds"> 
    {this.state.data2.map(opt => (
    <option value={opt}>{opt}</option> 
))} 
</select>