Parameter Specification

A parameter is represented by a JSON object which defines the parameter's properties. Parameters are typically defined together as a list within a Form.

Specification

key	type	required	dynamic	default value	description
name	string	yes	no	n\a	The unique identifier for parameter. Note that if this is empty, and the parameter is added to a form, it will be renamed to something non-empty (and unique within the form.)
type	enum	yes	no	n/a	The parameter type.
valueType	enum: string, stringEncoded, stringEncodedParts	yes	no	n/a	The type of the literal value. Internal Only: StringEncoded will fully fmeParsableText encode the value. StringEncodedParts is for values that are lists where the list elements/values should be fmeParsableText encoded but not the list itself.
defaultValue	any	no	no	n/a	The default value of the parameter.
prompt	string	conditional	no	n/a	A human-readable prompt for the parameter. Required when showPrompt is true.
showPrompt	boolean	no	no	varies based on parameter type	As a general rule, parameters which span multiple lines (tables, groups, etc) do not show the prompt by default and rely on the outer group to provide context.
supportedValueTypes	array\: ["expression", "globalParameter", "null", "noOp", "none"]	no	no	["globalParameter"]	A list of value setting methods to allow. "expression" includes attribute values. "literal" is not included in the enumeration as literal values are always allowed. To exclude all value types except literals, specify ["none"].
required	boolean	no	no	true	If true a value must be entered for the parameter of the transformer will appear invalid.
setValue	string, object	no	yes	n/a	Logic to control the value of the parameter. Default is not to modify value.
visibility	enum, boolean	no	yes	visibleEnabled	Logic to control enabling, disabling and hiding the parameter.
expressionSettings	dictionary	no	no	n/a	A dictionary of settings related to defining an expression value type.
choiceSettings	dictionary	no	no	n/a	A dictionary of settings related to defining the choice list this parameter may present.

deprecated

key	type	required	dynamic	default value	description
hidden	boolean	no	no	false	If true parameter will not be shown in the ui, but its value will be stored. (Replaced by visibility.)
deprecatedFlags	array\: ["wholeline", "showZipButton", "noEdit", "disabledOnly", "alwaysEnabled", "forceDefs", "ignoreValue"]	no	no	n/a	Allows specifying a list of legacy flags. Note: setting this should be avoided at all costs when making new transformers or new versions of transformers.

expressionSettings

key	type	required	internal	default value	description
sourcePorts	array\	no	no	[]	A string list of port names where attributes can be referred to.
supportsConditionals	boolean	no	no	true	Whether or not the expression supports conditionals.
supportsAbort	boolean	no	no	false	Whether or not abort can be used as a value.
subsequentFeatures	integer	no	yes	0	Number of subsequent adjacent features to access for attribute references. Valid number values are integers in the interval [-1, 100]. If -1 is specified, the maximum number is used.
priorFeatures	integer	no	yes	0	Number of prior adjacent features to access for attribute references. Valid number values are integers in the interval [-1, 100]. If -1 is specified, the maximum number is used.

choiceSettings

key	type	required	default value	description
choiceSet	enum	yes	userDefined	For text-based types, a keyword identifying a predefined set of choices to use for this parameter. By default, the encodings set includes fme-system (encoding of the operating system) and fme-binary (binary).
include	array\	no	n/a	A list of values to intersect with the choices defined by a choice set. Using 'exclude' at the same time as 'include' is not supported since it does not make sense.
exclude	array\	no	n/a	A list of values to exclude from the choices defined by a choice set.
sort	enum: noSort, naturalSort	yes	varies based on choice set	Whether or not to sort the choice list. Default is for user defined choice sets is to do natural sort. The default varies for other choice sets. For example, encodings are sorted with the most common first. AttributeNames are alphabetic.
choices	array\	no	n/a	A list of dictionaries with the following keys, specifying a choice list used by the 'dropdown' and 'listbox' types. If present a text widget will have an additional dropdown that allows the user to select from a list of values. Only applicable on textbox-based types.

choices

key	type	required	default value	description
value	string	yes	n/a	The value of the choice to be used in the backend.
useValueInTextEditor	boolean	no	false	If true the value will be shown to the user instead of the display string.
display	string	no	value	The display string to be shown to the user. The string will be translated before being shown. If you have a choice that does not require translation, do not specify this property.
icon	path	no	n/a	The path to an image file to use as an icon, shown as part of the choice.
textFormatting	dictionary	no	n\a	A dictionary of formatting options to apply to the choice.

textFormatting

key	type	required	default value	description
bold	boolean	no	false	If true the display text will be bold.
italic	boolean	no	false	If true the display text will be italicized.
strikeout	boolean	no	false	If true the display text will be stricken out.
underline	boolean	no	false	If true the display text will be underlined.

Types

• checkbox
• color
• datetime
• dropdown
• file
• font
• geometry
• group
• icon
• listbox
• message
• multi
• number
• password
• radio
• range
• table
• text
• tree

Choice Sets

• userDefined
• attributeNames
• coordinateSystems
• dbConnections
• dynamicServiceValues
• encodings
• exposableFormatAttributes
• geometryTransformations
• pointCloudComponents
• pointCloudTypes
• readers
• readerValues
• webConnections
• writers

Dynamic Properties

For interactions between parameters, see dynamicproperties

visibility

value	description
visibleEnabled	The parameter will be enabled and visible in the UI, unless its parent parameter ("group", "table", or "multi") is disabled and/or hidden.
visibleDisabled	The parameter will visible, but disabled.
hiddenEnabled	The parameter will hidden from the UI but be treated as enabled internally.
hiddenDisabled	The parameter will hidden from the UI and disabled internally.
true	Synonym for "visibleEnabled".
false	Synonym for "hiddenEnabled".
other value or undefined	Default to "visibleEnabled".

visibility Example:

"visibility": {
  "if": [{
    "$hasValue": {
      "parameter": "OFF_BUTTON",
      "value": "OFF"
    },
    "then": "visibleDisabled"
  }]
}

setValue

type	description
string	The parameter value will be set to this string value.
object	The parameter value will be set to object "value", but subject to extra conditions.
other types or undefined	The parameter value will not be modified

"value" Object

key	type	required	description
value	string	yes	The parameter value may be set to this string value.
override	boolean	yes	If false, then "value" will be only be set if the user has not input a value. Otherwise the "value" will be set unconditionally.

value string Example:

"value": {
  "if": [{
    "$hasValue": {
      "parameter": "X_MAKES_OTHER_Y",
      "value": "X"
    },
    "then": "Y"
  }]
}

In the above example, if "X_MAKES_OTHER_Y" has value "X", then the parameter value will be unconditionally set to "Y".

value object Example:

"value": {
  "if": [{
    "$hasValue": {
      "parameter": "IF_X_THEN_SET_TO_Y_BUT_DONT_OVERRIDE",
      "value": "X"
    },
    "then": {
      "value": "Y",
      "override": false
    }
  }]
}

In the above example, if "IF_X_THEN_SET_TO_Y_BUT_DONT_OVERRIDE" has value "X", then the parameter value will be set to "Y" if the user has not input a value for the parameter.

Example

  "parameters": [
    {
      "name": "MESSAGE",
      "type": "text",
      "valueType": "stringEncoded",
      "supportedValueTypes": ["expression", "globalParameter", "conditional"],
      "prompt": "Log Message",
      "required": true,
      "defaultValue": "Feature is:"
    },
    {
      "name": "MAXCOORDS",
      "type": "number",
      "valueType": "string",
      "supportedValueTypes": ["expression", "globalParameter", "conditional"],
      "prompt": "Max Coordinates Per Feature",
      "required": true,
      "defaultValue": 20,
      "precision": 0
    },
    {
      "name": "MAXFEATS",
      "type": "number",
      "valueType": "string",
      "supportedValueTypes": ["expression", "globalParameter", "conditional"],
      "prompt": "Max Features to Log",
      "required": true,
      "defaultValue": 20,
      "precision": 0
    },
    {
      "name": "FEATURE_TYPE",
      "type": "text",
      "valueType":  "stringEncoded",
      "supportedValueTypes": ["expression", "globalParameter", "conditional"],
      "prompt": "Feature Type Override",
      "required": "false"
    }
  ]