Parameter

Résumé

Every tool parameter has an associated Parameter object with properties and methods that are useful in tool validation.

Discussion

Although many Parameter object properties are read/write, most of these properties can only be set or modified when you initially create or modify the object. Several properties, including name, displayName, datatype, direction, and parameterType, establish the characteristics of a tool and cannot be modified during validation methods (such as updateMessages and updateParameters).

Syntaxe

 Parameter  ({name}, {displayName}, {direction}, {datatype}, {parameterType}, {enabled}, {category}, {symbology}, {multiValue})

Paramètre	Explication	Type de données
name	The parameter name. (La valeur par défaut est None)	String
displayName	The parameter label as shown on the tool's dialog box. (La valeur par défaut est None)	String
direction	The Input/Output direction of the parameter. (La valeur par défaut est None)	String
datatype	The data type of the parameter. For a list of parameter data types, see Geoprocessing data types. (La valeur par défaut est None)	String
parameterType	parameterType can be Required, Optional, or Derived. Derived means that the user of your tool does not enter a value for the parameter. Derived types are always output parameters. (La valeur par défaut est None)	String
enabled	False if the parameter is unavailable. (La valeur par défaut est None)	Boolean
category	The category of the parameter. (La valeur par défaut est None)	String
symbology	The path to a layer file (.lyr) used for drawing the output. (La valeur par défaut est None)	String
multiValue	True if the parameter is a multivalue parameter. (La valeur par défaut est None)	Boolean

Propriétés

Propriété	Explication	Type de données
altered (Lecture seule)	True if the user has modified the value.	Boolean
category (Lecture/écriture)	The category of the parameter.	String
columns (Lecture/écriture)	The column data types and names of a value table parameter are set using a list of lists. import arcpy param = arcpy.Parameter() param.datatype = "GPValueTable" param.columns = [["GPFeatureLayer", "Features"], ["GPLong", "Ranks"]]	String
datatype (Lecture/écriture)	The data type of the parameter. For a list of parameter data types, see Geoprocessing data types.	String
defaultEnvironmentName (Lecture/écriture)	The geoprocessing environment setting used to set the parameter's default value.	String
direction (Lecture/écriture)	The Input/Output direction of the parameter.	String
displayName (Lecture/écriture)	The parameter label as shown on the tool's dialog box.	String
enabled (Lecture/écriture)	False if the parameter is unavailable.	Boolean
filter (Lecture seule)	The filter to apply to values in the parameter.	Filter
filters (Lecture/écriture)	Similar to filter but used to support value table parameters. class SampleTool(object): # __init__ left out to simplify example def getParameterInfo(self): in_fc = arcpy.Parameter( name='in_features', displayName='Input Features', datatype='GPFeatureLayer', direction='Input', parameterType='Required') vt = arcpy.Parameter( name = 'summary_fields', displayName = 'Summary fields', datatype = 'GPValueTable', direction = 'Input', parameterType = 'Optional') vt.parameterDependencies = [in_fc.name] vt.columns = [['Field', 'Field'], ['GPString', 'Statistic'], ['GPDouble', 'Multiplier']] vt.filters[0].list = ['Double', 'Float', 'Short', 'Long'] vt.filters[1].type = 'ValueList' vt.filters[1].list = ['SUM', 'MIN', 'MAX', 'MEAN'] vt.filters[2].type = 'Range' vt.filters[2].list = [0,10]	Filter
hasBeenValidated (Lecture seule)	True if the internal validation routine has checked the parameter.	Boolean
message (Lecture seule)	The message to be displayed to the user.	String
multiValue (Lecture/écriture)	True if the parameter is a multivalue parameter.	Boolean
name (Lecture/écriture)	The parameter name.	String
parameterDependencies (Lecture/écriture)	A list of indexes of each dependent parameter. In a script tool, parameterDependencies is set with a list of parameter indexes; in a Python toolbox tool, parameterDependencies is set with a list of parameter names.	Integer
parameterType (Lecture/écriture)	parameterType can be Required, Optional, or Derived. Derived means that the user of your tool does not enter a value for the parameter. Derived types are always output parameters. Required —A Required parameter requires an input value from the user. The tool cannot be executed until a value has been supplied. Optional — An Optional parameter does not require a value. Derived —A Derived parameter is only for output parameters. A derived output parameter does not show on the tool dialog box.	String
schema (Lecture seule)	The schema of the output dataset.	Schema
symbology (Lecture/écriture)	The path to a layer file (.lyr) used for drawing the output.	String
value (Lecture/écriture)	The value of the parameter.	Object
valueAsText (Lecture seule)	The value of the parameter as a string. Remarque : For Python toolboxes only.	String
values (Lecture/écriture)	The values of the Value Table parameter, which is set using a list of lists.	Variant

Vue d’ensemble des méthodes

Méthode	Explication
clearMessage ()	Clears out any message text and sets the status to informative (no error or warning).
hasError ()	Returns True if the parameter contains an error. To evaluate whether a parameter has an error, hasError should be called within the tool validation's updateMessages method.
hasWarning ()	Returns True if the parameter contains a warning.
isInputValueDerived ()	Returns True if the tool is being validated inside a Model and the input value is the output of another tool in the model.
setErrorMessage (message)	Sets a parameter as having an error with the supplied message. Tools do not execute if any of the parameters have an error.
setIDMessage (message_type, message_ID, {add_argument1}, {add_argument2})	Sets a parameter as having a system message.
setWarningMessage (message)	Sets a parameter as having an error with the supplied message. Unlike errors, tools will execute with warning messages.

Méthodes

clearMessage ()

hasError ()

Valeur renvoyée

Type de données	Explication
Boolean	True if the parameter contains an error.

hasWarning ()

Valeur renvoyée

Type de données	Explication
Boolean	True if the parameter contains a warning.

isInputValueDerived ()

Valeur renvoyée

Type de données	Explication
Boolean	True if the tool is being validated inside a Model and the input value is the output of another tool in the model.

setErrorMessage (message)

Paramètre	Explication	Type de données
message	The string to be added as an error message to the geoprocessing tool messages.	String

setIDMessage (message_type, message_ID, {add_argument1}, {add_argument2})

Paramètre	Explication	Type de données
message_type	Defines whether the message will be an error or a warning. ERROR —The message will be an error message. WARNING —The message will be a warning message.	String
message_ID	The message ID allows you to reference existing system messages.	Integer
add_argument1	Depending on which message ID is used, an argument may be necessary to complete the message. Common examples include dataset or field names. The data type is variable depending on the message.	Object
add_argument2	Depending on which message ID is used, an argument may be necessary to complete the message. Common examples include dataset or field names. The data type is variable depending on the message.	Object

setWarningMessage (message)

Paramètre	Explication	Type de données
message	The string to be added as a warning message to the geoprocessing tool messages.	String

Exemple de code

Parameter example

Enabling or disabling a parameter in a ToolValidator class.

def updateParameters(self):
    # If the option to use a weights file ("Get Spatial Weights From File") 
    # is selected, enable the parameter for specifying the file; 
    # otherwise, disable it

    if self.params[3].value == "Get Spatial Weights From File":
        self.params[8].enabled = True
    else:
        self.params[8].enabled = False

    return

Parameter example 2

Setting a default value for a parameter in a ToolValidator class.

def updateParameters(self):
    # Set the default distance threshold to 1/100 of the larger of
    # the width or height of the extent of the input features.  Do
    # not set if there is no input dataset yet, or the user has set
    # a specific distance (Altered is true).

    if self.params[0].value:
        if not self.params[6].altered:
            extent = arcpy.Describe(self.params[0].value)
        width = extent.XMax - extent.XMin
        height = extent.YMax - extent.YMin

        if width < height:
            self.params[6].value = width / 100
        else:
            self.params[6].value = height / 100

        return

Parameter example 3

Setting a custom error message for a parameter in a ToolValidator class.

def updateMessages(self):
    self.params[6].clearMessage()

    # Check to see if the threshold distance contains a value of
    # zero and the user has specified a fixed distance band.
    if self.params[6].value <= 0:
        if self.params[3].value == "Fixed Distance Band":
            self.params[6].setErrorMessage(
                "Zero or a negative distance is invalid when "
                "using a fixed distance band. Please use a "
                "positive value greater than zero.")
        elif self.params[6].value < 0:
            self.params[6].setErrorMessage(
                "A positive distance value is required when "
                "using a fixed distance band. Please specify "
                "a distance.")

    return