Link To The Current Page With Query Params

The link_to method is an ActionView helper for generating an a tag within a Rails view. There are two arguments that tend to comprise this method: the link text and a path helper.

<%= link_to 'Home', root_path %>

The link_to method can be used to generate a link to the current page with query params. You can do this be providing a hash instead of a path helper as the second argument.

<%= link_to "All", {filter: 'all'} %>
<%= link_to "New", {filter: 'new'} %>
<%= link_to "Posted", {filter: 'posted'} %>

The hash can contain one or more key-value pairs which will be turned into query params and appended to the end of the current base path.

If these are part of the posts index page, then they will render as:

<a href="/posts?filter=all">All</a>
<a href="/posts?filter=new">New</a>
<a href="/posts?filter=posted">Posted</a>

This is a great way to create links for a Rails action that presents different data based on query params. Often this is an index page where filtering is needed.

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