Class: QgsProcessingParameterString¶

A string parameter for processing algorithms.

A parameter type which allows users to enter any string value.

In some circumstances it is desirable to restrict the values available when a user is asked to enter a string parameter to a list of predetermined “valid” values. Since QGIS 3.22 this can be done by setting the widget wrapper metadata “value_hints” option, as demonstrated below. (While this provides a mechanism for guiding users to select from valid string values when running a Processing algorithm through the GUI, it does not place any limits on the string values accepted via PyQGIS codes or when running the algorithm via other non-gui means. Algorithms should gracefully handle other values accordingly.)

param = QgsProcessingParameterString( 'PRINTER_NAME', 'Printer name')
# show only printers which are available on the current system as options
# for the string input.
param.setMetadata( {'widget_wrapper':
  { 'value_hints': ['Inkjet printer', 'Laser printer'] }
})

Class Hierarchy¶

Base classes¶

QgsProcessingParameterDefinition

Base class for the definition of processing parameters.

class qgis.core.QgsProcessingParameterString[source]¶

Bases: QgsProcessingParameterDefinition

__init__(name: str | None, description: str | None = '', defaultValue: Any = None, multiLine: bool = False, optional: bool = False)

Constructor for QgsProcessingParameterString.

Parameters:

name (Optional[str])
description (Optional[str] = '')
defaultValue (Any = None)
multiLine (bool = False)
optional (bool = False)

__init__(a0: QgsProcessingParameterString)

Parameters:: a0 (QgsProcessingParameterString)

static fromScriptCode(name: str | None, description: str | None, isOptional: bool, definition: str | None) → QgsProcessingParameterString | None[source]¶

Creates a new parameter using the definition from a script code.

Parameters:

name (Optional[str])
description (Optional[str])
isOptional (bool)
definition (Optional[str])

Return type:

Optional[QgsProcessingParameterString]

multiLine(self) → bool[source]¶

Returns True if the parameter allows multiline strings.