Creating Array from Object in ActionScript

Question

I've got an object which was deserialized from JSON. It looks like this, introspected in FlashBuilder:

Cities //object
   Denver //object, contained within Cities
       description "Mile High City"
       location "Colorado"
   Los Angeles//object, contained within Cities
       description "City of Angels"
       location "California"
   New York //object, contained within Cities
       description "The Big Apple"
       location "New York State"

All I'm trying to do is to create an array of cities, so that I can do something like this: trace(arrCities[i].description); //returns "Mile High City" or "City of Angels" depending on the value of i.

But I can't get at the strings. Among things I've tried, none of which work:

var arrCities:Array = objCities as Array; //doesn't work

And:

  for (var prop:String in objCities);       
  { 
     trace("objCities."+prop+" = "+objCities[prop]);
     trace(prop.description);  //this returns only one random description 
                              //(sometimes "The Big Apple, sometimes "City of Angels" etc.
     arrCities.push(objCities[prop]);

  }

and

  for each (var prop:String in objCities);      
  { 
     trace("objCities."+prop+" = "+objCities[prop]);
     trace(prop.description);  // returns "objCities.[object Object] = undefined"
     arrCities.push(objCities[prop]);

  }

There's got to be a simple solution to this but I can't find it. Any help appreciated.

Thanks.

cities: {
    denver: {
        dateCreated: 0
        description: "Mile High Cty"
        cityCode: "dv"
        cityName: "Denver"
        properties: { }
        title: ""
    }
    newyork: {
        dateCreated: 0
        description: "The Big Apple"
        cityCode: "nyc"
        cityName: "New York"
        properties: { }
        title: ""
    }
    losangeles: {
        dateCreated: 0
        description: "City of Angels"
        cityCode: "la"
        cityName: "Los Angeles"
        properties: { }
        title: ""
    }
}

If you can share the JSON, it will probably be easier to answer. — Lars Blåsjö
– Lars Blåsjö, Commented Jul 31, 2011 at 12:19

shanethehat · Accepted Answer · 2011-07-31 14:12:30Z

3

var objCities:Object = JSON.decode(objStr);
var arrCities:Array = [];

for each (var prop:Object in objCities)     
{ 
     arrCities.push(prop);
}
trace(arrCities[0].description);

Explaination:

The form for(var foo in bar) sets foo as the name of the current element of bar in the iteration. for each(var foo in bar) sets foo as the property of this element of bar. You want each each inner object, not that object's name, to be inserted in the array, so that you end up with an array of objects like {description:"City of Angels",location:"California"}

edited Jul 31, 2011 at 14:12

answered Jul 31, 2011 at 12:19

shanethehat

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7 Comments

David Over a year ago

Thanks -- but that doesn't work either. It gives me arrCities.length = 1. Sometimes it returns the New York object, sometimes LA, sometimes Denver. But only 1.

shanethehat Over a year ago

Then could you please post the original JSON string, and tell us what you're using to deserialize it? I'll need to properly recreate your object to see why this fails.

shanethehat Over a year ago

@David - stupid typo my my part, shouldn't be a semi-colon on the first line! The semi-colon terminates the loop, and then the code in braces only executes once for the first object property.

David Over a year ago

Yes!! You're a hero. Interesting (I did not know this) that within a for..in loop you don't use a semicolon. Last piece: What if I want to access something like description or cityCode?

shanethehat Over a year ago

You can use it inside the loop, just not where I did before my edit: for each() ; {

|

Kaken Bok · Accepted Answer · 2011-07-31 12:35:28Z

0

This library includes the facto standard of reading JSON into AS3 Objects: https://github.com/mikechambers/as3corelib. You will need to use it. To develop your own version of a JSON parser is in (probably) no case reasonable.

answered Jul 31, 2011 at 12:35

Kaken Bok

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5 Comments

David Over a year ago

Yes, I'm already using it. I've pulled in the JSON and converted it to objects. Now I need to get at the data in the objects. That's where I'm stuck.

Kaken Bok Over a year ago

Great, perhaps the cities are not a list and the JSON parser returns you an object instead of an enumerated array. Is this right? trace (this what json parser returns);

Kaken Bok Over a year ago

Than you access your cities either via loop over the object properties (for in) or - if you know the cities - directly using the citiy as key: jsonReturnObj[myCityName][description].

David Over a year ago

Thanks but I've tried that as shanethehat suggested and it returns one item. I then tried a nested loop, ie looping through each city, but that also didn't work. Looks like I'll have to post some JSON....

David Over a year ago

I've posted the JSON. By the way I don't know the city names. What I'm trying to do is populate a combobox with them. The JSON changes, listing different cities according to various criteria, so I need to dynamically read in the city names from the JSON.

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