FLUID-5300: fluid.transforms.valueMapper requires outputValue (or outputPath) being specified for the output object

Description

When a literal value needs to be mapped to an object that has multiple paths and values, for example:

var inputModel = {
    hazard: "flashing"
};

var expectedTransformedObject = {
    hasHazard: true,
    audio: true
};

The transformation rule that performs this transformation successfully looks like:

{
    type: "fluid.transforms.valueMapper",
    inputPath: "hazard",
    options: {
        "flashing": {
            "outputValue": {
                transform: [{
                    type: "fluid.transforms.literalValue",
                    value: true,
                    outputPath: "hasHazard"
                }, {
                    type: "fluid.transforms.literalValue",
                    value: true,
                    outputPath: "sound"
                }]
            }
        }
    }
};

Note that in this rule:
1. "outputValue" needs to be specified as a key in the map options;
2. Nested transformation rules needs to be defined for each output key value pair rather than a direct compound values.

It would be nice to simplify the rule to be:

{
    type: "fluid.transforms.valueMapper",
    inputPath: "hazard",
    options: {
        "flashing": {
            "hasHazard": true,
            "sound": true
        }
    }
}

In today's conversation at irc channel, Antranig expressed concerns that the implementation of the valueMapper is not consistent with that of our other transforms:

https://botbot.me/freenode/fluid-work/2014-04-02/?tz=America/Havana

at 11:19AM onwards.

Comments

• Antranig Basman commented 2016-04-15T12:01:10.399-0400

  Two changes have altered the terrain around this issue since it was filed -
  i) FLUID-5867 altered the default framework behaviour on encountering nested transforms to be consistent with this behaviour
  ii) We supported the "literalValue": "x" syntax to more compactly encode literal values

• Antranig Basman commented 2016-04-15T12:04:42.185-0400

  With these changes, cindy's transform becomes

  {
      type: "fluid.transforms.valueMapper",
      inputPath: "hazard",
      options: {
          "flashing": {
              "outputValue": {
                  "hasHazard": true
                  "sound": true
              }
          }
      }
  };
  

  which I think is pretty reasonable