How to Render Partial in Rails: Syntax and Examples

In Rails, you render a partial using render partial: 'partial_name' or simply render 'partial_name'. Partials are reusable view templates that help keep your code DRY and organized.

Syntax

Use render partial: 'partial_name' or the shorthand render 'partial_name' to include a partial view. The partial file should start with an underscore, like _partial_name.html.erb.

You can also pass local variables with locals: { key: value } to customize the partial.

erb

<%= render partial: 'shared/header' %>

<%= render 'shared/header' %>

<%= render 'shared/item', locals: { item: @item } %>

Example

This example shows rendering a partial named _greeting.html.erb that displays a greeting message. The partial receives a local variable name.

erb

<!-- app/views/home/index.html.erb -->
<h1>Welcome Page</h1>
<%= render 'greeting', locals: { name: 'Alice' } %>

<!-- app/views/home/_greeting.html.erb -->
<p>Hello, <%= name %>! Welcome to our site.</p>

Output

<h1>Welcome Page</h1>
<p>Hello, Alice! Welcome to our site.</p>

Common Pitfalls

• Forgetting the underscore prefix in the partial filename (e.g., use _partial.html.erb, not partial.html.erb).
• Not passing required local variables, causing errors inside the partial.
• Using render partial: with a full path but missing the underscore.
• Trying to render a partial without the correct file extension.

erb

<!-- Wrong: missing underscore -->
<%= render 'header' %> <!-- Will fail if file is named header.html.erb instead of _header.html.erb -->

<!-- Right: with underscore -->
<%= render 'header' %> <!-- Works if file is _header.html.erb -->

Quick Reference

Tips for rendering partials in Rails:

• Partial filenames start with an underscore.
• Use render 'partial_name' for simplicity.
• Pass variables with locals: { key: value }.
• Keep partials small and focused for reuse.

Key Takeaways

Render partials with render 'partial_name' where the file starts with an underscore.

Pass data to partials using locals: { key: value } to customize content.

Always name partial files with a leading underscore to be recognized by Rails.

Keep partials focused and reusable to maintain clean views.

Avoid missing underscores or forgetting to pass required locals to prevent errors.