Allow data values to refer to user-defined variables

[Vince Bickers]

For example:

"name":"loaded", "value": "$timestamp"

[Vince Bickers]

This is now available. e.g.

    {
      "type": "Bronze",
      "update_strategy": "unique",
      "labels": [{ "name": "Medal" }],
      "identity": ["BRONZE_MEDAL", "sport", "year", "athlete"],
      "condition": "bronze > 0",
      "properties": [{"name": "total", "column": "bronze"}]
    },
...

  "values": [
    { "name": "OLYMPICS",        "value": "Olympics"},
    { "name": "GOLD_MEDAL",      "value": "Gold" },
    { "name": "SILVER_MEDAL",    "value": "Silver" },
    { "name": "BRONZE_MEDAL",    "value": "Bronze" }
  ]

Here, the variable BRONZE_MEDAL is referred to in the declaration of the node typeBronze. There is no field with this name in the input data set, so the importer obtains the required value from the variable - in this case "Bronze".