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Parameter

Dans cette rubrique

  1. Résumé
  2. Discussion
  3. Syntaxe
  4. Propriétés
  5. Vue d’ensemble des méthodes
  6. Méthodes
  7. Exemple de code
Rubriques connexes
  1. Définition des paramètres des outils de script
  2. Value
  3. Filter
  4. Schema
  5. Customizing script tool behavior

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})
ParamètreExplicationType 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

The parameterType property can be Required, Optional, or Derived.

(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 (.lyrx or .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

PropriétéExplicationType de données
altered
(Lecture seule)

True if the user has modified the value.

Boolean
category
(Lecture et écriture)

The category of the parameter.

String
columns
(Lecture et 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 et écriture)

The data type of the parameter.

For a list of parameter data types, see Geoprocessing data types.

String
defaultEnvironmentName
(Lecture et écriture)

The geoprocessing environment setting used to set the parameter's default value.

String
direction
(Lecture et écriture)

The Input/Output direction of the parameter.

String
displayName
(Lecture et écriture)

The parameter label as shown on the tool's dialog box.

String
displayOrder
(Lecture et écriture)

The order in which a parameter is displayed on the tool's dialog box. This may be different from the order the parameters are accessed from Python.

Integer
enabled
(Lecture et écriture)

False if the parameter is unavailable.

Boolean
filter
(Lecture seule)

The filter to apply to values in the parameter.

Filter
filters
(Lecture et 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 et écriture)

True if the parameter is a multivalue parameter.

Boolean
name
(Lecture et écriture)

The parameter name.

String
parameterDependencies
(Lecture et 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 et écriture)

The parameterType property can be Required, Optional, or Derived.

In validation, the parameterType value cannot be dynamically modified. However, it may be necessary to have a parameter behave as required or optional depending on other parameter settings. If this is the case, set the parameter as optional. Then, in the validation updateMessages method, use the Parameter setIDMessage method with message ID 735. Using message ID 735 causes an optional parameter to behave as a required parameter.

  • Required—The parameter requires a value for the tool to execute.
  • Optional— The parameter does not require a value for the tool to execute.
  • Derived—The tool returns an output value that is not provided as an input parameter. Derived parameters are always output parameters.
String
schema
(Lecture seule)

The schema of the output dataset.

Schema
symbology
(Lecture et écriture)

The path to a layer file (.lyrx or .lyr) used for drawing the output.

String
value
(Lecture et écriture)

The value of the parameter.

Object
valueAsText
(Lecture seule)

The value of the parameter as a string.

String
values
(Lecture et écriture)

The values of a Value Table parameter, which is set using a list of lists.

Variant

Vue d’ensemble des méthodes

MéthodeExplication
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 donnéesExplication
Boolean

True if the parameter contains an error.

hasWarning ()
Valeur renvoyée
Type de donnéesExplication
Boolean

True if the parameter contains a warning. 

isInputValueDerived ()
Valeur renvoyée
Type de donnéesExplication
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)
ParamètreExplicationType 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})
ParamètreExplicationType 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)
ParamètreExplicationType 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

Rubriques connexes

  • Définition des paramètres des outils de script
  • Value
  • Filter
  • Schema
  • Customizing script tool behavior

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Dans cette rubrique
  1. Résumé
  2. Discussion
  3. Syntaxe
  4. Propriétés
  5. Vue d’ensemble des méthodes
  6. Méthodes
  7. Exemple de code
Rubriques connexes
  1. Définition des paramètres des outils de script
  2. Value
  3. Filter
  4. Schema
  5. Customizing script tool behavior