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Parameter

In diesem Thema

  1. Zusammenfassung
  2. Diskussion
  3. Syntax
  4. Eigenschaften
  5. Methodenübersicht
  6. Methoden
  7. Codebeispiel
Verwandte Themen
  1. Festlegen von Parametern für Skriptwerkzeuge
  2. Value
  3. Filter
  4. Schema
  5. Customizing script tool behavior

Zusammenfassung

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

Diskussion

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).

Syntax

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

The parameter name.

(Der Standardwert ist None)

String
displayName

The parameter label as shown in the Geoprocessing pane.

(Der Standardwert ist None)

String
direction

The direction of the parameter.

(Der Standardwert ist None)

String
datatype

The data type of the parameter.

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

(Der Standardwert ist None)

String
parameterType

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

(Der Standardwert ist None)

String
enabled

False if the parameter is unavailable.

(Der Standardwert ist None)

Boolean
category

The category of the parameter.

(Der Standardwert ist None)

String
symbology

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

(Der Standardwert ist None)

String
multiValue

True if the parameter is a multivalue parameter.

(Der Standardwert ist None)

Boolean

Eigenschaften

EigenschaftErläuterungDatentyp
altered
(Schreibgeschützt)

True if the user has modified the value.

Boolean
category
(Lesen und schreiben)

The category of the parameter.

String
charts
(Lesen und schreiben)

A list of Chart objects that are added to an output parameter.

Object
columns
(Lesen und schreiben)

The structure of the columns in a value table parameter.

The columns are organized in a list of lists, with each inner list representing the column data type, column name, and an optional read-only value. If the read-only value is set to ReadOnly, the column cannot be modified by the user.


import arcpy
param = arcpy.Parameter()
param.datatype = "GPValueTable"
param.columns = [["GPFeatureLayer", "Features"], ["GPLong", "Ranks"]]
String
controlCLSID
(Lesen und schreiben)

A class identifier that can be used to override the default control for the data type.

Learn more about parameter controls

String
datatype
(Lesen und schreiben)

The data type of the parameter.

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

String
defaultEnvironmentName
(Lesen und schreiben)

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

String
direction
(Lesen und schreiben)

The direction of the parameter.

String
displayName
(Lesen und schreiben)

The parameter label as shown in the Geoprocessing pane.

String
displayOrder
(Lesen und schreiben)

The order in which a parameter is displayed in the Geoprocessing pane. This may be different from the order the parameters are accessed from Python.

Integer
enabled
(Lesen und schreiben)

False if the parameter is unavailable.

Boolean
filter
(Schreibgeschützt)

The filter to apply to values in the parameter.

Filter
filters
(Lesen und schreiben)

Similar to the filter property, but it is 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
(Schreibgeschützt)

True if the internal validation routine has checked the parameter.

Boolean
message
(Schreibgeschützt)

The message to be displayed to the user.

String
multiValue
(Lesen und schreiben)

True if the parameter is a multivalue parameter.

Boolean
name
(Lesen und schreiben)

The parameter name.

String
parameterDependencies
(Lesen und schreiben)

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
(Lesen und schreiben)

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

In validation, the parameterType value cannot be dynamically modified. However, it may be necessary for a parameter to behave as a required parameter or an optional parameter 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 530 or 735. Using message ID 530 or 735 will cause an optional parameter to behave as a required parameter.

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

The schema of the output dataset.

Schema
symbology
(Lesen und schreiben)

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

String
value
(Lesen und schreiben)

The value of the parameter.

Object
valueAsText
(Schreibgeschützt)

The value of the parameter as a string.

String
values
(Lesen und schreiben)

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

Variant

Methodenübersicht

MethodeErläuterung
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.

Methoden

clearMessage ()
hasError ()
Rückgabewert
DatentypErläuterung
Boolean

True if the parameter contains an error.

hasWarning ()
Rückgabewert
DatentypErläuterung
Boolean

True if the parameter contains a warning. 

isInputValueDerived ()
Rückgabewert
DatentypErläuterung
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)
ParameterErläuterungDatentyp
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})
ParameterErläuterungDatentyp
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)
ParameterErläuterungDatentyp
message

The string to be added as a warning message to the geoprocessing tool messages.

String

Codebeispiel

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

Verwandte Themen

  • Festlegen von Parametern für Skriptwerkzeuge
  • Value
  • Filter
  • Schema
  • Customizing script tool behavior

Feedback zu diesem Thema?

In diesem Thema
  1. Zusammenfassung
  2. Diskussion
  3. Syntax
  4. Eigenschaften
  5. Methodenübersicht
  6. Methoden
  7. Codebeispiel
Verwandte Themen
  1. Festlegen von Parametern für Skriptwerkzeuge
  2. Value
  3. Filter
  4. Schema
  5. Customizing script tool behavior