从存储中调用api，并将数据绑定到ReactJS / flux中的组件状态

Question

Using React-router-component, i have set to load my home page with a component called gigist which is as folows:

var React = require('react');
var AppStore =require('../../stores/app-store.js');
var GigsListItem = require('./giglistitem.js');
var StoreWatchMixin =require('../../mixins/StoreWatchMixin.js');

function getGigs()
{

    return {items:AppStore.getGigs()}
}

var GigsList= React.createClass({
  mixins:[new StoreWatchMixin(getGigs)],
  componentWillMount:function()
  {
     this.setState(getGigs());
     console.log(this.state);
  },
  componentDidMount:function()
  {
     this.setState(getGigs());
     console.log(this.state);
  },
    render:function()
    {
        console.log("rendered view");
        var liststyle={border:'1px solid black'};

        /*
        var items=this.state.items.map(function(item)
        {
            return <GigsListItem gig={item} />
        })  */
        return (

                <div className="row" style={liststyle}>
                {this.state.items}

                </div>
               )
    }
});

module.exports=GigsList;

I am making an ajax call using npm reqwest,but the problem is that the view is being rendered and setting its state to undefined before completion of ajax request. You can see it from my console log

From the console '1' is at setting initial state for component giglist,'3' is component will mount,'rendered view' is while rendering component,'2' is for the ajax request

which clearly states that data is not being set to component state after the ajax call.

I need to set state for the component after i get response from it. I tried setting state with componentwillmount and componentdidmount but neither solve my issue.

here is my store code:

var AppDispatcher = require('../dispatchers/app-dispatcher');
var AppConstants = require('../constants/app-constants');
var reqwest = require('reqwest');
var merge = require('react/lib/merge');
var EventEmitter = require('events').EventEmitter;

var CHANGE_EVENT = "change";

var _gigs = [];

function getGigsList()
{

reqwest({url:'myapi',
type:'get',
success:function(resp)
{
  console.log(2);
  return resp.gigs;  
  //alert(JSON.stringify(_gigs));
}.bind(this)})  


}  



var _cartItems = [];


function _removeItem(index){
  _cartItems[index].inCart = false;
  _cartItems.splice(index, 1);
}

function _increaseItem(index){
  _cartItems[index].qty++;
}

function _decreaseItem(index){
  if(_cartItems[index].qty>1){
    _cartItems[index].qty--;
  }
  else {
    _removeItem(index);
  }
}


function _addItem(item){
  if(!item.inCart){
    item['qty'] = 1;
    item['inCart'] = true;
    _cartItems.push(item);
  }
  else {
    _cartItems.forEach(function(cartItem, i){
      if(cartItem.id===item.id){
        _increaseItem(i);
      }
    });
  }
}

function _CartTotals()
{
  var qty=0,total=0;
  _cartItems.forEach(function(cartItem)
    {
       qty+=cartItem.qty;
       total+=cartItem.cost * cartItem.qty;

    });
  return {'qty':qty,'total':total}
}


var AppStore = merge(EventEmitter.prototype, {
  emitChange:function(){
    this.emit(CHANGE_EVENT)
  },

  addChangeListener:function(callback){
    this.on(CHANGE_EVENT, callback)
  },

  removeChangeListener:function(callback){
    this.removeListener(CHANGE_EVENT, callback)
  },

  getCart:function(){
    return _cartItems
  },

  getGigs:function(){
    alert(JSON.stringify(getGigsList()));
    return getGigsList();
  },

  getCartTotals:function()
  {
    return _CartTotals();
  },

  dispatcherIndex:AppDispatcher.register(function(payload){
    var action = payload.action; // this is our action from handleViewAction
    switch(action.actionType){
      case AppConstants.ADD_ITEM:
        _addItem(payload.action.item);
        break;

      case AppConstants.REMOVE_ITEM:
        _removeItem(payload.action.index);
        break;

      case AppConstants.INCREASE_ITEM:
        _increaseItem(payload.action.index);
        break;

      case AppConstants.DECREASE_ITEM:
        _decreaseItem(payload.action.index);
        break;
    }
    AppStore.emitChange();

    return true;
  })
})

module.exports = AppStore;

can somebody point out where i am doing wrong.I hope i am clear.Thanks in advance

Answer 1

You cannot use return statements in asynchronous code, ie, in the success callback of your ajax-call.

Instead, try to check if there are already gigs in the store, in which case you return them, and if there are no gigs in the store you do a request to get some and in the success callback you set the store state to the new data and emit a change that will tell your component to try to fetch the store state again.

    function getGigsList()
    {
        if (_gigs.length > 0) { return _gigs; } //return immediately if data exists

        reqwest({url:'myapi',
        type:'get',
        success:function(resp)
        {
            console.log(2);
            _.gigs = resp.gigs;  
            this.emit(CHANGE_EVENT);
        }.bind(this)}) 

        return _gigs; //currently an empty array. this way you don't have to check for undefined in the component, you can just iterate over it directly
    }