Relation Mapper

If you have already checked the PMD manual, you know that a PMD file can define relations between models. When these relations are parsed, they are stored in a Julia dictionary, the Relation Mapper.

Relation Mapper JSON file

However, it is also possible to fill the Relation Mapper with a JSON file, that follows the same structure as OpenStudy's dictionary for relations.

In the example below, we have a Relation Mapper file with the following information:

• The model CustomModel has two relations defined, one with SecondCollection and another with ThirdCollection.
  • The relation with SecondCollection is a 1_to_1 relation, and the parameter is called system.
  • The relation with ThirdCollection is a 1_to_N relation, and the parameter is called station.
• The model SecondCollection has two relations with FourthCollection.
  • The first relation with FourthCollection is a FROM relation, and the parameter is called no1.
  • The second relation with FourthCollection is a TO relation, and the parameter is called no2.

{
    "CustomCollection": {
        "SecondCollection": {
            "system": {
                "is_vector": false,
                "type": "1_TO_1"
            }
        },
        "ThirdCollection": {
            "station": {
                "is_vector": true,
                "type": "1_TO_N"
            }
        }
    },
    "SecondCollection": {
        "FourthCollection": {
            "no1": {
                "is_vector": false,
                "type": "FROM"
            },
            "no2": {
                "is_vector": false,
                "type": "TO"
            }
        }
    }
}