"values" should be expressed as "constraints"/"enum"

[danfowler]

We can now specify that a given column must be one of several values in core JSON Table Schema. We can use the "enum" constraint for this:

http://specs.frictionlessdata.io/json-table-schema/#field-constraints

 {
  "name": "status",
  "description": "",
  "type": "string",
  "values": ["active", "inactive", "defunct", "temporarily closed"]
}

is better expressed as:

 {
  "name": "status",
  "description": "",
  "type": "string",
  "constraints": {
    "enum": ["active", "inactive", "defunct", "temporarily closed"]
  }
}

[timgdavies]

Thanks @danfowler for flagging this.

@robredpath If I don't get to it before you are working on docs generation next week, please update the sample data first so that you are working on the latest frictionless data specs.

[robredpath]

@timgdavies @danfowler 2512e77

[NeilMcKLogic]

This is great news, interoperability will be greatly improved if we constrain fields either to a finite list like this or at least a data type. As such, can we consider adding such "type" constraints to other fields like email addresses and ensure other obvious fields like boolean and date/datetime get these constraints too?

[robredpath]

Further constraints would be great for interoperability and we're likely to be recommending them for a future version of HSDS. Thanks @NeilMcKechnie !

[robredpath]

@NeilMcKechnie Issue #99 may be of interest to you as well.