RubyMine 2020.2 Help

Code completion

This section covers various techniques of context-aware code completion that allow you to speed up your coding process.

Basic completion

Basic code completion helps you complete the names of classes, methods, and keywords within the visibility scope. When you invoke code completion, RubyMine analyses the context and suggests the choices that are reachable from the current caret position (suggestions also include Live templates).

Invoke basic completion

  1. Start typing a name.

  2. Press Ctrl+Space or choose Code | Code Completion | Basic from the main menu.

    Basic completion

  3. If necessary, press Ctrl+Space for the second time (or press Ctrl+Alt+Space).

    The completion popup shows all declared names. In this case, RubyMine suggests text-based results regardless of whether they are appropriate in the current context.

    Declared names completion

Hippie completion

Hippie completion is a completion engine that analyses your text in the visible scope and generates suggestions from the current context. It helps you complete any word from any of the currently opened files.

Expand a string at caret to an existing word

  1. Type the initial string and do one of the following:

    • Press Alt+/ or choose Code | Code Completion | Cyclic Expand Word to search for matching words before the caret.

    • Press Alt+Shift+/ or choose Code | Code Completion | Cyclic Expand Word (Backward) to search for matching words after the caret and in other open files.

    The first suggested value appears, and the prototype is highlighted in the source code.

    Expand word
  2. Accept the suggestion, or hold the Alt key and keep pressing / until the desired word is found.

Postfix code completion

Postfix code completion helps you reduce backward caret jumps as you write code. You can transform an already-typed expression to a different one based on a postfix you type after the dot, the type of expression, and its context.

  • To view a full list of available postfix templates, in the Settings/Preferences dialog Ctrl+Alt+S, go to Editor | General | Postfix Completion.

  • Select Tab, Space, or Enter to expand postfix templates.

Transform a statement with a postfix

  1. Type an expression and then type a postfix after a dot, for example, .if:

    Postfix completion
  2. (Optional step) If required, select an expression that will be used as a condition:

    Postfix completion expression
  3. Press Enter:

    Postfix completion result

To disable certain postfix completion templates, in the Settings/Preferences dialog Ctrl+Alt+S select Editor | General | Postfix Completion.

You can selectTab, Space, or Enter to expand postfix templates.

You can edit the predefined postfix templates, for example, to replace a long key with a shorter one, or to expand the list of applicable expression types.

Create custom postfix templates

  1. In the Settings/Preferences dialog Ctrl+Alt+S, go to Editor | General | Postfix Completion.

  2. Click the Add button on the toolbar.

  3. Specify the Key, that is the combination of symbols that will invoke the template, select which expression types the new template will be applicable to, and type the target expression in the following format: $EXPR$ <target_expression>, for example, $EXPR$ =!null.

Completion of tags and attributes

RubyMine automatically completes names and values of tags and attributes in many file types:

Complete tag names

  1. Press < and start typing the tag name. RubyMine displays the list of tag names appropriate in the current context.

    Tags completion

    Use the Up and Down buttons to scroll through the list.

  2. Press Enter to accept a selection from the list. If your file is associated with a schema or a DTD, RubyMine automatically inserts the mandatory attributes according to it.

Import a taglib declaration

If you need to use tags declared in a tag library, you need to import this taglib before any custom tag from it can be used.

  1. Start typing a taglib prefix and press Alt+Insert.

  2. Select a taglib from the list and press Enter.

    Import taglib declaration

    RubyMine imports the selected taglib and adds the import statement automatically.

Insert a tag declared in a taglib

  1. Start typing a tag and press Ctrl+Alt+Space.

  2. Select a tag from the list. The uri of the taglib it belongs to is displayed in brackets.

    Tag completion: before

  3. Select the desired taglib and press Enter. RubyMine adds the declaration of the selected taglib:

    Tag completion: after

Configure code completion settings

To configure code completion options, In the Settings/Preferences dialog Ctrl+Alt+S go to Editor | General | Code Completion.

You can choose the following settings:



Match caseSelect if you want letter case to be taken into account for completion suggestions. Choose whether you want to match case for the first letter or for all letters.
Automatically insert single suggestions for Select if you want to automatically complete code if there's just one suggestion for basic and/or smart completion.
Sort suggestions alphabetically

Select if you want to sort items in the suggestions list in the alphabetical order instead of sorting them by relevance.

You can change this behavior at any time by clicking icons.actions.more.svg in the suggestion list and toggling the Sort by Name option.

Show suggestions as you type Select if you want the suggestions list to be invoked automatically, without having to call completion explicitly. This option is enabled by default.
Insert selected suggestion by pressing space, dot, or other context-dependent keysSelect if you want to insert the selected suggestion by typing certain keys that depend on the language, your context, and so on.
Show the documentation popup in

Select to automatically show a popup for each item in the suggestions list with the documentation for the class, method, or field currently highlighted in the lookup list.

In the field to the right, specify the delay (in milliseconds), after which the popup should appear.

Preselect first completion element Choose this option if you want to preselect the first item in the suggestions list.

Completion tips and tricks

Narrow down the suggestions list

  • You can narrow down the suggestions list by typing any part of a word (even characters from somewhere in the middle) or invoking code completion after a dot separator . RubyMine will show suggestions that include the characters you've entered in any positions.

    This makes the use of wildcards unnecessary:

    code completion wildcard

    In case of CamelCase or snake_case names, type the initial letters only. RubyMine automatically recognizes and matches the initial letters.

    code completion wildcard

Accept a suggestion

You can accept a suggestion from the list in one of the following ways:

  • Press Enter or double-click a list item to insert it to the left of the caret.

  • Press Tab to replace the characters to the right from the caret.

  • Use Ctrl+Shift+Enter to make the current code construct syntactically correct (balance parentheses, add missing braces and semicolons, and so on).

You can also use specific keys to insert the selected completion suggestion: in the Settings/Preferences dialog Ctrl+Alt+S choose Editor | General | Code Completion and select the Insert selected suggestion by pressing space, dot, or other context-dependent keys option. These keys depend on the language, your context, and so on.

View reference

  • You can use the Definitions by pressing Ctrl+Shift+I when you select an entry in the suggestions list:

    completion quick definition
  • You can use the Quick Information view by pressing Ctrl+Q when you select an entry in the suggestions list:

    Quick documentation

View code hierarchy

You can view code hierarchy when you've selected an entry from the suggestions list:

  • Ctrl+H - view type hierarchy

  • Ctrl+Shift+H - view method hierarchy.

Use machine-learning-assisted code completion

You can utilize machine learning models to rank most suitable items higher in the suggestions list.

To do this, in the Settings/Preferences dialog Ctrl+Alt+S go to Editor | General | Code Completion and enable the Rank completion suggestions based on Machine Learning option under Machine Learning-Assisted Completion.


    If code completion doesn't work, this may be due to one of the following reasons:

    • The Power Save Mode is on (File | Power Save Mode). Turning it on minimizes power consumption of your laptop by eliminating the background operations, including error highlighting, on-the-fly inspections, and code completion.

    • An SDK is not configured for your project.

    • Your file doesn't reside in a content root , so it doesn't get the required class definitions and resources needed for code completion.

    • A file containing classes and functions that you want to appear in completion suggestions list is marked as a plain text file.

    • External libraries that contain functions that you want to appear in the completion suggestions list are not added as dependencies or global libraries .

    Last modified: 19 August 2020