/// Select values in nested [List] and [Map] structures using a path that may contain wildcards. /// /// The maps must always use [String] keys. /// The [path] is a dot-separated list of keys and indices. /// The wildcard "*" can be used to select all elements of a list or map. /// The wildcard "**" can be used to select all elements of a list or map and all elements of nested lists and maps. /// /// Returns an [Iterable] of the selected values. /// /// Also see [selectInJsonWithPath] for a version that returns the path to the selected values. Iterable selectInJson(dynamic json, String path) { return selectInJsonWithPath(json, path).map((e) => e.value); } Map> selectMultipleInJson( dynamic json, Map selector) { Map> result = {}; for (String key in selector.keys) { result[key] = selectInJsonWithPath(json, selector[key]!); } return result; } /// Select values in nested [List] and [Map] structures using a path that may contain wildcards. /// /// The maps must always use [String] keys. /// The [path] is a dot-separated list of keys and indices. /// The wildcard "*" can be used to select all elements of a list or map. /// The wildcard "**" can be used to select all elements of a list or map and all elements of nested lists and maps.+ /// /// Returns an [Iterable] of the selected values and their path. Iterable<({T value, String path})> selectInJsonWithPath( dynamic json, String path) sync* { if (path.isEmpty) { if (json is T) { yield (value: json, path: ""); } return; } List pathParts = path.split("."); String first = pathParts.removeAt(0); String rest = pathParts.join("."); addFirstToPath(({T value, String path}) element) => ( value: element.value, path: element.path.isEmpty ? first : "$first.${element.path}" ); if (first == "*" || first == "**") { String continueWithPath = first == "*" ? rest : path; if (json is List) { yield* json .expand((e) => selectInJsonWithPath(e, continueWithPath)) .map(addFirstToPath); } else if (json is Map) { for (String key in json.keys) { yield* selectInJsonWithPath(json[key], continueWithPath) .map(addFirstToPath); } } } else if (json is List) { try { int index = int.parse(first); yield* selectInJsonWithPath(json[index], rest); } catch (e) { // The first part of the path is not an index or out of bounds -> ignore } } else if (json is Map) { dynamic value = json[first]; if (value != null) { yield* selectInJsonWithPath(value, rest); } } }