Question

我在Meteor.call程序的范围上遇到了很多麻烦。它不会将我的范围变量设置为result.length

'takeaways': function (userId) {
    var len = 0;

    Meteor.call('userTakeaways', userId, function (error, result) {
        if (error) {
            console.log('there was an error finding the number of messages that were takeaways')
        } else {
            len = result.length; // result.length is 2
        }
    });

    console.log(len); // still 0

    return len;
}

请帮忙！

谢谢：）

Answer 1

len不是反应变量。因此，如果len值发生变化，则不会更新空格键值。

所以这里有两种解决这个问题的方法： 1.使用反应性var / session。

 //Make sure you have install reactive var package  
    var len = new ReactiveVar(0); 
    Template['name'].helpers({ 
        'takeaways': function (userId) {
            Meteor.call('userTakeaways', userId, function (error, result) {
               if (error) {
                   console.log('there was an error finding the number of messages that were takeaways')
               } else {
                  len.set(result.length); // result.length is 2
               }
           }); 
        console.log(len.get()); // You will get 2 when response come from you method call. 
        return len.get(); 
        } 
     });

2。使用＆＃39; simple：reactive-method＆＃39;封装

 takeaways : function(userId){
      return ReactiveMethod.call('userTakeaways', userId).length;
  }

Answer 2

尝试添加else语句

return len = result.length;

正如你可以看到的那样。

'takeaways': function (userId) {
    var len = 0;

    Meteor.call('userTakeaways', userId, function (error, result) {
        if (error) {
            console.log('there was an error finding the number of messages that were takeaways')
        } else {
            return len = result.length; // result.length is 2
        }
    });

console.log(len); // still 0

return len;

}

不会设置Meteor调用范围变量

2 个答案: