Question

我有一个返回承诺的简单服务。但是，如果它是基元，它只触发then（）。我无法想象我的生活。任何帮助将不胜感激。我意识到这可能是一件简单的事情，但我已经查看了许多例子，并且无法弄清楚为什么它不能从我的服务中返回我的对象。

02-12 12:29:03.728 8994-8994/? I/zygote: Not late-enabling -Xcheck:jni (already on)
02-12 12:29:03.784 8994-8994/? W/zygote: Unexpected CPU variant for X86 using defaults: x86
02-12 12:29:03.856 8994-9002/? E/zygote: Failed writing handshake bytes (-1 of 14): Broken pipe
02-12 12:29:03.856 8994-9002/? I/zygote: Debugger is no longer active
02-12 12:29:03.878 8994-9002/? W/zygote: Suspending all threads took: 22.488ms
02-12 12:29:03.944 8994-8994/? I/InstantRun: starting instant run server: is main process
02-12 12:29:04.303 8994-9016/? D/OpenGLRenderer: HWUI GL Pipeline

                                                 [ 02-12 12:29:04.401  8994: 9016 D/         ]
                                                 HostConnection::get() New Host Connection established 0x9a926e80, tid 9016
02-12 12:29:04.459 8994-8999/? I/zygote: Do partial code cache collection, code=9KB, data=18KB
02-12 12:29:04.459 8994-8999/? I/zygote: After code cache collection, code=9KB, data=18KB
02-12 12:29:04.459 8994-8999/? I/zygote: Increasing code cache capacity to 128KB
02-12 12:29:04.460 8994-8999/? I/zygote: Do partial code cache collection, code=9KB, data=36KB
02-12 12:29:04.460 8994-8999/? I/zygote: After code cache collection, code=9KB, data=36KB
02-12 12:29:04.460 8994-8999/? I/zygote: Increasing code cache capacity to 256KB
02-12 12:29:04.460 8994-8999/? I/zygote: JIT allocated 71KB for compiled code of void android.widget.TextView.<init>(android.content.Context, android.util.AttributeSet, int, int)
02-12 12:29:04.460 8994-8999/? I/zygote: Compiler allocated 4MB to compile void android.widget.TextView.<init>(android.content.Context, android.util.AttributeSet, int, int)
02-12 12:29:04.595 8994-9016/? I/zygote: android::hardware::configstore::V1_0::ISurfaceFlingerConfigs::hasWideColorDisplay retrieved: 0
02-12 12:29:04.595 8994-9016/? I/OpenGLRenderer: Initialized EGL, version 1.4
02-12 12:29:04.595 8994-9016/? D/OpenGLRenderer: Swap behavior 1
02-12 12:29:04.714 8994-9016/? D/EGL_emulation: eglCreateContext: 0xa50e6160: maj 2 min 0 rcv 2
02-12 12:29:04.753 8994-9016/? D/EGL_emulation: eglMakeCurrent: 0xa50e6160: ver 2 0 (tinfo 0xa501b6f0)
02-12 12:29:04.863 8994-9016/com.example.sparsh.newcalculator D/EGL_emulation: eglMakeCurrent: 0xa50e6160: ver 2 0 (tinfo 0xa501b6f0)
02-12 12:29:07.446 8994-8994/com.example.sparsh.newcalculator I/Choreographer: Skipped 174 frames!  The application may be doing too much work on its main thread.
02-12 12:29:12.710 8994-8994/com.example.sparsh.newcalculator D/AndroidRuntime: Shutting down VM
02-12 12:29:12.711 8994-8994/com.example.sparsh.newcalculator E/AndroidRuntime: FATAL EXCEPTION: main
                            Process: com.example.sparsh.newcalculator, PID: 8994
                            java.lang.NumberFormatException: For input string: " 666"
                                at java.lang.Integer.parseInt(Integer.java:597)
                                at java.lang.Integer.parseInt(Integer.java:643)
                                at com.example.sparsh.newcalculator.MainActivity$11.onClick(MainActivity.java:147)
                                at android.view.View.performClick(View.java:6294)
                                at android.view.View$PerformClick.run(View.java:24770)
                                at android.os.Handler.handleCallback(Handler.java:790)
                                at android.os.Handler.dispatchMessage(Handler.java:99)
                                at android.os.Looper.loop(Looper.java:164)
                                at android.app.ActivityThread.main(ActivityThread.java:6494)
                                at java.lang.reflect.Method.invoke(Native Method)
                                at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438)
                                    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807)

修改

它似乎与类型有关。如果我使用Point，它可以正常工作。

//CreateLayer inside IncidentLayer class
public CreateLayer(): Promise<any>{         
   return this.incidentService.getIncidents().toPromise().then((incs) => {
        var gfx = this.createGraphics(incs);//not an async function
        var lyr = new this._mapDependencies.FeatureLayer({
            source: gfx              
        });

        //return lyr;WILL NOT TRIGGER
        return "test";//WORKS
    }); 

}
 ......
  this.incidentLayer.CreateLayer().then((lyr)=>{
          console.log(lyr);//only triggers if lyr is a primitive
        });

我在控制台或添加catch（）之后没有错误，所以我不确定如何调试它。

_mapDependencies通过以下esri角度加载器库创建。

var lyr = new this._mapDependencies.Point();
return lyr;//works

Answer 1

您的CreateLayer（）函数不会返回承诺！您无法解决承诺并将其作为承诺返回。使用RxJs obserables会更容易，但承诺的解决方案应如下所示：

public CreateLayer(): Promise<any>{         
   return new Promise(resolve=>{
   this.incidentService.getIncidents().toPromise().then((incs) => {
        var gfx = this.createGraphics(incs);//not an async function
        var lyr = new this._mapDependencies.FeatureLayer({
            source: gfx              
        });    
        resolve(lyr);
       })
    }); 
}

我用另一个承诺包装你的getIncidents（），这是将回复给将调用此函数的任何人的承诺。当它被解析时，调用函数.then（）回调将是

你应该多读一些关于承诺如何运作here

的内容

Angular 2承诺不归还对象

1 个答案: