angular 2+从本地json文件中获取特定值

Question

I want to fetch only a certain object from the file. But I somehow only can fetch the entire data from the file.

So far my method to fetch the data looks like this:

getGeoCityFromLocalFile(lon, lat) {
    return this.http.get('/assets/city-list.json')
    .map(res => res.json()).subscribe(res => {
         If(res.coord.lon === lon && res.coord.lat === lat) {
             this.cityStatsStorage = res;
             console.log(this.cityStatsStorage);
             return this.cityStatsStorage;
         }
    });
}

I want to fetch only this Object where the lon an lan Input are the same.

Answer 1

Your problem lies in here:

If(res.coord.lon === lon && res.coord.lat === lat)

Res is an array and not a single object, so you would need a loop. Example:

for (var i=0; i<res.length; i++){
   if (res[i].coord.lon === lon && res[i].coord.lat === lat){
      this.cityStatsStorage = res[i];
      console.log(this.cityStatsStorage);
      return this.cityStatsStorage;
   }
}