用$ q.all在promise中调用promise [重复]

Question

这个问题已经在这里有了答案：

• 多个诺言并行运行，$ q.all是否需要链接？ 1个答案

我有多个可以并行运行的api请求。

getlocations，getstates，get领地可以并行发出请求。 但是，一旦我从getstates（）调用获得了状态列表，就需要为每个单独的状态发出api请求并解析状态对象。

这是我到目前为止的代码，可以这样在诺言中调用诺言吗？

  getAllLocations() {
    //make a promise call for all here .
    var promise = [];
    //first prmise
    promise.push(this.getAllLocations(Id).then(
        (locationsData) => {
            this.locations = locationsData;
        }));
    //second promise
    promise.push(this.getAllStates(Id).then(
        (resp) => {
            this.states = resp.data;
            //for each state , need to make an api call and add to the state info
            angular.forEach(this.states, function(state){
                var nodeId = state.Id;
                this.getStateSummary(nodeId).then((resp) => {
                    state.healthStatus = resp.data.operationalStatus;
                });
            },this)
        }));
    //third promise
    promise.push(this.getAllterritories(Id).then(
        (resp) => {
            this.territories = resp.data;
        }));
    //after all promises parse teh location data
    $q.all(promise).then(() => {
        for (var i = 0; i < this.locations.length; i++) {
            //do something with with location here
        }
        this.gridData = this.locations;
    });
}

如果没有，打电话给getStatesummary（）的最佳方法是什么？

Answer 1

我将简化三个承诺中的每一个（尤其是1和3），以便this.locations，this.states和this.territories都在$ q.all中进行更新。然后-您不必这样做，但是我认为它使代码更具可读性

接下来，将所有3个Promise分配给一个变量（以下代码中的p1，p2，p3）

下一个问题是等待所有状态的API调用完成-在那里需要另外$ q.all

全部完成，再加上一点ES6优势，您将获得

getAllLocations() {
    //first prmise
    const p1 = this.getAllLocations(Id);
    //second promise
    const p2 = this.getAllStates(Id).then(resp => 
        //for each state , need to make an api call and add to the state info
        $q.all(resp.map(state => this.getStateSummary(state.Id).then(resp => state.healthStatus = resp.data.operationalStatus)))
        .then(() => resp) // so we return data for this.states
    );
    //third promise
    const p3 = this.getAllterritories(Id).then(resp => resp.data);
    //after all promises parse teh location data
    $q.all([p1, p2, p3]).then(([locations, states, territories]) => {
        this.locations = locations;
        this.states = states;
        this.territories = territories;
        for (var i = 0; i < locations.length; i++) {
            //do something with with location here
        }
        this.gridData = this.locations;
    });
}

如果getAllStates承诺返回一个Object而不是我的假设，它是一个数组-那么将内部$q.all替换为

        $q.all(Object.entries(resp).map(([key, state]) => this.getStateSummary(state.Id).then(resp => state.healthStatus = resp.data.operationalStatus)))

实际上，以上代码同样适用于Array或Object：p

Answer 2

您可以使用承诺链一个接一个地发送承诺

 getAllLocations() {
     //make a promise call for all here .
     var promise = [];
     //first prmise
     this.getAllLocations(Id)
         .then(
             (locationsData) => {
                 this.locations = locationsData;
                 promise.push(this.locations);

                 return this.getAllStates(Id)
             }).then(
             (resp) => {
                 this.states = resp;
                 //for each state , need to make an api call and add to the state info
                 angular.forEach(this.states, function(state) {
                     var nodeId = state.Id;
                     return this.getStateSummary(nodeId);
                 }, this)
                 return this.getAllterritories(Id);
             }).then((resp) => {
             state.healthStatus = resp.data.operationalStatus;
             promise.push(state.healthStatus);
         }).then(
             (resp) => {
                 this.territories = resp.data;
                 promise.push(this.territories);
                 this.callAll(promise)
             })
 }


 callAll(promise) {
     //after all promises parse teh location data
     this.$q.all(promise).then(() => {
         for (var i = 0; i < this.locations.length; i++) {
             //do something with with location here
         }
         this.gridData = this.locations;
     });
 }