QGIS/resources/function_help/json/is_selected

{
  "name": "is_selected",
  "type": "function",
  "description": "Returns True if a feature is selected. Can be used with zero, one or two arguments, see below for details.",
  "variants": [
        {
            "variant": "No parameters",
            "variant_description": "If called with no parameters, the function will return true if the current feature in the current layer is selected.",
            "arguments": [],
            "examples": [ { "expression": "is_selected()", "returns" : "True if the current feature in the current layer is selected." } ]
        },
        {
            "variant": "One 'feature' parameter",
            "variant_description": "If called with a 'feature' parameter only, the function returns true if the specified feature from the current layer is selected.",
            "arguments": [ { "arg": "feature", "description": "The feature which should be checked for selection." } ],
            "examples": [ { "expression": "is_selected(@atlas_feature)", "returns": "True if the current atlas feature is selected." } ]
        },
        {
            "variant" : "Two parameters",
            "variant_description": "If the function is called with both a layer and a feature, it will return true if the specified feature from the specified layer is selected.",
            "arguments": [ { "arg": "layer", "description": "The layer (or its ID or name) on which the selection will be checked." }, { "arg": "feature", "description": "The feature which should be checked for selection." } ],
            "examples": [ { "expression": "is_selected( 'streets', get_feature('streets', 'name', \"street_name\"))", "returns": "True if the current building's street is selected (assuming the building layer has a field named 'street_name' and the 'streets' layer has a field called 'name')." } ]
        }
  ]
 }