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Facets in JSON

Kinds of Facets

See the corresponding XML list for definitions.

XML Facet JSON Facet Text Num Date
enumeration enum X    
fractionDigits n/a      
length minLength
maxLength		 X    
maxLength maxLength X    
minLength minLength X    
minExclusive minimum
exclusiveMinimum: true		   X  
minInclusive minimum   X  
maxExclusive maximum
exclusiveMaximum: true		   X  
maxInclusive maximum   X  
pattern pattern X    
totalDigits n/a      
whiteSpace n/a      

Draft 6 of the JSON Schema specification changes the types of exclusiveMinimum and exclusiveMaximum from booleans to numbers so that they may be used without also requiring minimum and maximum.

Enumerations

Enumerations are defined within a simple type declaration in the oneOf array. Each enumeration is defined as an object with enum and description properties.

Defining enumerations in an array is a JSON Schema requirement. Since NIEM requires definitions for enumerations, the object must be repeated with a single enumeration in each enum array and a corresponding description.

{
  "oneOf" : [
    { "enum": [ "1" ], "description": "…" },
    { "enum": [ "2" ], "description": "…" },
    { "enum": [ "3" ], "description": "…" }
  ]
}

This example shows the definition of iso_4217:CurrencyCodeSimpleType with three enumerations:

{
  "definitions": {
    "iso_4217:CurrencyCodeSimpleType": {
      "type": "string",
      "description": "A data type for a currency that qualifies a monetary amount.",
      "oneOf": [
        {
          "enum": [ "EUR" ],
          "description": "Euro"
        },
        {
          "enum": [ "GBP" ],
          "description": "Pound Sterling"
        },
        {
          "enum": [ "USD" ],
          "description": "US Dollar"
        }
      ]
    }
  }
}

Numeric Range

This example shows a numeric simple type with a minimum and a maximum value:

{
  "definitions": {
    "my:CustomRangeSimpleType": {
      "description": "A data type for ...",
      "type": "integer",
      "minimum": 0,
      "maximum": 100
    },
  }
}
  • The base type may be set to number instead of integer to allow for decimal values.
  • Add the properties exclusiveMinimum: true and exclusiveMaximum: true to make the range exclusive of the edge values.

Generic Template

This template shows the definition of a simple type with a base:

{
  "definitions": {
    "SIMPLE_TYPE": {
      "description": "TYPE_DEFINITION",
      "type": "BASE_TYPE",
      "FACET_KIND": "FACET_VALUE"
    },
  }
}
  • SIMPLE_TYPE - this should be a qualified name that ends with SimpleType.
  • BASE_TYPE - this should be either string, number, or integer.
  • FACET_KIND - this should be one of the values defined in the JSON facets table above.

Example of a string type with a maximum length:

{
  "definitions": {
    "ext:NAMESimpleType": {
      "description": "A data type for...",
      "type": "string",
      "maxLength": 20
    },
  }
}