Prepare a compound input argument — qgis_list

Some algorithm arguments require a compound object, consisting of several layers or elements. These functions apply strict validation rules when generating this object and are recommended.

Usage

qgis_list_input(...)

qgis_dict_input(...)

Arguments

...: Named values for qgis_dict_input() or unnamed values for qgis_list_input().

Value

qgis_list_input(): An object of class 'qgis_list_input'
qgis_dict_input(): An object of class 'qgis_dict_input'

Details

qgis_list_input() generates an unnamed list of class qgis_list_input. The use of qgis_list_input() instead of list() is required for compound arguments in case of no-JSON input (see qgis_using_json_input()). Since it applies strict validation rules, it is recommended in all cases though.

qgis_dict_input() generates a named list of class qgis_dict_input. qgis_dict_input() is only supported when the JSON input method applies (see qgis_using_json_input()), where it can be interchanged with a named list(). It can only be used for arguments requiring named lists. Since it applies strict validation rules, it is recommended above list().

Some QGIS argument types that need a compount object are the multilayer, aggregates, fields_mapping, tininputlayers and vectortilewriterlayers argument types.

Examples

qgis_list_input(1, 2, 3)
#> [[1]]
#> [1] 1
#> 
#> [[2]]
#> [1] 2
#> 
#> [[3]]
#> [1] 3
#> 
#> attr(,"class")
#> [1] "qgis_list_input"
qgis_dict_input(a = 1, b = 2, c = 3)
#> $a
#> [1] 1
#> 
#> $b
#> [1] 2
#> 
#> $c
#> [1] 3
#> 
#> attr(,"class")
#> [1] "qgis_dict_input"