How to deserialize JSON to a class where the same variable name has different data types?

Question

I am trying to deserialize some JSON to a class using JSON.deserialize. My JSON looks like this

{
    "type": "GeometryCollection",
    "geometries": [
        {
            "type": "Point",
            "coordinates": [-3.529138029308078, 50.71957856160531]
        }, 
        {
            "type": "Polygon",
            "coordinates": [
                [
                    [-3.5381984710693364, 50.72477461305143],
                    [-3.5381984710693364, 50.727165282893836],
                    [-3.5295295715332036, 50.727165282893836],
                    [-3.5295295715332036, 50.72477461305143],
                    [-3.5381984710693364, 50.72477461305143]
                ]
            ]
        }
    ]
}

and the class I am trying to use looks like this

public class geometryCollection 
{
  String type;   
  List<geometry> geometries; 
}

public class geometry 
{
  String type;
  /*List<Decimal> coordinates;
  List<List<List<Decimal>>> coordinates;*/
}

As you can see in my JSON the items in the 'geometries' array have a type and coordinates. The problem is that for a point the coordinates are of type List<Decimal> and for polygon they are of type List<List<List<Decimal>>>.

Is there a good way to deserialize this JSON when two different data types use the same name?

Answer 1

So I decided the easiest way is to do a find and replace on the JSON string and change the names of one of the duplicate variables.

String s2 = geoJSON.replace('"coordinates":[[[', '"polygonCoordinates":[[[');

Then I updated my classes to look like this

public class geometryCollection
{
   String type;   
   List<geometry> geometries; 
}

public class geometry
{
   String type;
   List<Decimal> coordinates;
   List<List<List<Decimal>>> polygonCoordinates;
}

Then once I have serialized the JOSN I can change it back.

Answer 2

maton, anyone who encounters this use case,

I had a similar use case. I ended up opensourcing my take on this https://github.com/gaelmotte/apex-json-serialization

After deploying, your code can be adapted as such:

public class GeometryCollection 
{
  String type;   
  List<Geometry> Geometries; 
}

public abstract class Geometry implements JSONDeserializer.Deserializable, JSONDeserializer.Polymorph
{
  String type;
   public virtual void setDeserializedField(String key, Object value) {
      switch on key {
        when 'type' {
          this.type = (String) value;
        }
      }
    }
    public virtual Map<String, System.Type> getDeserializableFields() {
      return new Map<String, System.Type>{ 'type' => String.class };
    }
}

public class GeometryDiscriminator implements JSONDeserializer.Discriminator {
    public System.Type discriminate(Map<String, Object> untyppedMap) {
      if (untyppedMap.get('type') == 'Point') {
        return PointGeometry.class;
      }
      return PolygonGeometry.class;
    }
  }

public PointGeometry extends Geometry {
  List<Decimal> coordinates;
 public override void setDeserializedField(String key, Object value) {
      switch on key {
        when 'coordinates' {
          this.coordinates = (List<Decimal>) value;
        }
        when else {
          super.setDeserializedField(key, value);
        }
      }
    }
    public override Map<String, System.Type> getDeserializableFields() {
      Map<String, System.Type> fields = super.getDeserializableFields();
      fields.putAll(new Map<String, System.Type>{ 'coordinates' =>  List<Decimal>.class });
      return fields;
    }
}

public PolygonGeometry extends Geometry {
  List<List<List<Decimal>>> coordinates;
 public override void setDeserializedField(String key, Object value) {
      switch on key {
        when 'coordinates' {
          this.coordinates = (List<List<List<Decimal>>>) value;
        }
        when else {
          super.setDeserializedField(key, value);
        }
      }
    }
    public override Map<String, System.Type> getDeserializableFields() {
      Map<String, System.Type> fields = super.getDeserializableFields();
      fields.putAll(new Map<String, System.Type>{ 'coordinates' =>  List<List<List<Decimal>>>.class });
      return fields;
    }
}

I agree this is more tedious to setup, but much cleaner (polymorphism may benefit you in the long run). I wish there were some kind of custom annotations or introspection, but too bad...