ReSharper DevGuide

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Create a Context Action

What you should know beforehand:

Examples (?):

The purpose of context actions is to quickly introduce a minor change to the code, like changing access modifiers, convert foreach to for, and so on. When a context action is available for the current caret position, ReSharper displays the “hummer” hummer action indicator. The list of possible context actions is displayed after a user presses Alt+Enter.

context-action

For example, let’s create a very simple context action that will be applicable to variable declarations. If a variable name contains any character in uppercase, the context action will suggest to convert the name to lowercase (of course, from the point of functionality, such action is absolutely useless).

[ContextAction(Name = "ToLowerCase", Description = "Convert the text to lowercase", Group = "C#", Disabled = false, Priority = 1)] public class ToLowerCaseContextAction : ContextActionBase { private readonly IVariableDeclaration _nodeUnderCaret; public ToLowerCaseContextAction(LanguageIndependentContextActionDataProvider dataProvider) { _nodeUnderCaret = dataProvider.GetSelectedElement<IVariableDeclaration>(); } protected override Action<ITextControl> ExecutePsiTransaction(ISolution solution, IProgressIndicator progress) { return textControl => { var newText = _nodeUnderCaret.DeclaredName.ToLower(); RenameRefactoringService.Rename(solution, new RenameDataProvider((IDeclaredElement) _nodeUnderCaret, newText), textControl); }; } public override string Text => "Convert to lowercase"; public override bool IsAvailable(IUserDataHolder cache) { var nodeText = _nodeUnderCaret?.DeclaredName; var containsUpperCase = nodeText != null && nodeText.Any(char.IsUpper); return containsUpperCase; } }

Notes

  • The easiest way to create a context action is to inherit from the ContextActionBase class.
  • The context action class must be marked with the ContextAction attribute:
    • Group defines the scope of the action (C# files in our case).
    • Disabled specifies whether the action is disabled by default.
    • Priority sets the position of the action in the actions list.
  • The context data provider LanguageIndependentContextActionDataProvider obtained in the constructor provides a super-helpful method GetSelectedElement that returns the tree node under the caret. The provider has also methods that allow you to get current offset, selection range and so on.
  • The Text property defines the text that will be shown in the actions list.
  • IsAvailable is used to check whether the action is available for the current caret position. If false, the action is not shown in the list of possible context actions.
  • ExecutePsiTransaction returns the action that is executed when the context action is selected.
  • Note that we use RenameRefactoringService to change variable’s name. The service performs seamless renaming of a variable everywhere in the code.
Last modified: 12 July 2017