A Value object is returned from GetParameterInfo when used in a script tool's ToolValidator class, and from the GetParameter function depending on the parameter type.


PropertyExplanationData Type
(Read Only)

Indicates whether the value object is empty.


If a parameter has no value, the parameter's value property will return a NoneType and the isEmpty property will be inaccessible. To determine whether a parameter has a value, use an if check against the Parameter value property, for example, if param.value:.

(Read and Write)

Provides the value of the value object.


Code sample

Value example

UpdateParameter populates a value list for the second parameter based on the attribute names of NetCDF file.

def updateParameters(self):
    """Modify the values and properties of parameters before internal
    validation is performed.  This method is called whenever a parameter
    has been changed."""

    # If the parameter has been altered, but not validated
    if self.params[0].altered and not self.params[0].hasBeenValidated:
        # Create a NetCDFFIleProperties object based on the input and
        #   use it to populate the value list of the sceond parameter.
        net_cdf = arcpy.NetCDFFileProperties(self.params[0].value.value)
        att_names = net_cdf.getAttributeNames()
        self.params[1].filter.list = att_names
        self.params[1].value = att_names[0]


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