CODEWITHSUNDEEP
javascriptjson
Lali
Lali

Reputation: 13

Is there a way to get access to json items if the key name is unknown?

I want to access json items from generated keys (generated in php and encoded to json). Is it possible to increment a variable to access it?

Here is my generated JSON (sorry it looks weird in here):

{
"build1":{
  "object_id":1,
  "object_type":"school",
  "object_x":628,
  "object_y":131
  },
"build2":{
  "object_id":11,
  "object_type":"house",
  "object_x":631,
  "object_y":101
  },
"build3":{
  "object_id":12,
  "object_type":"school",
  "object_x":498,
  "object_y":131
  },
"build4":{
  "object_id":13,
  "object_type":"house",
  "object_x":770,
  "object_y":154
  },
"build5": {"object_id":14,
  "object_type":"house",
  "object_x":526,
  "object_y":217
  },
"build6":{
  "object_id":15,
  "object_type":"house",
  "object_x":563,
  "object_y":264
  }
}

I tried to (poorly) do it with simple tricks but it doesn't work. Is there a way?

Here is my code:

for(var i=1; i<= buildingsLength; i++){

       var build= "build"+i;
       var buildaccess= "buildings"+"."+build;
       var buildType= buildaccess+"."+"object_type";

       if (buildType === "house"){
           console.log("yes, its a house");
           var img = new Image();
           img.src = "../img/house.png";
           img.onload = function(){
               ctx.drawImage(img,100,100);
           };
       }else if (buildType === "school") {
           console.log("yes, its a school");
           var img = new Image();
           img.src = "../img/school.png";
           img.onload = function(){
               ctx.drawImage(img,100,100);
           };
       }else{
           console.log("error");
       }
   }

I'd like to access "buildings.build1.object_type" but "build1" should somehow increment.

Upvotes: 0

Views: 74

Answers (2)

Nikita Iskorkin
Nikita Iskorkin

Reputation: 13

You can iterate over keys of object: 

Object.keys(yourJsonObject).forEach(key => console.log(`${key}: ${yourJsonObject[key]}`));

or you can access value by key declined in string: 

const myKey = "build2";
console.log(yourJsonObject[mykey]);
// Should log:
//  {
//   "object_id":11,
//   "object_type":"house",
//   "object_x":631,
//   "object_y":101
//   }

Upvotes: 0

Harun Yilmaz
Harun Yilmaz

Reputation: 8558

You can use Object.values() to get values of the object as an array. And then iterate over it:

const myJson = {
"build1":{
  "object_id":1,
  "object_type":"school",
  "object_x":628,
  "object_y":131
  },
"build2":{
  "object_id":11,
  "object_type":"house",
  "object_x":631,
  "object_y":101
  },
"build3":{
  "object_id":12,
  "object_type":"school",
  "object_x":498,
  "object_y":131
  },
"build4":{
  "object_id":13,
  "object_type":"house",
  "object_x":770,
  "object_y":154
  },
"build5": {"object_id":14,
  "object_type":"house",
  "object_x":526,
  "object_y":217
  },
"build6":{
  "object_id":15,
  "object_type":"house",
  "object_x":563,
  "object_y":264
  }
};

for(let build of Object.values(myJson)){
   switch(build.object_type){
      case 'house':{
        console.log("It's a house!");
        break;
      }
      case 'school':{
        console.log("It's a school!");
        break;
      }
      default: break;
   }
}

Upvotes: 2

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