Partials with Locals
Now that we learned about locals, let's refactor our old codebase and add a couple new features using this new tool.
Objectives
- Use the
locals
keyword - Understand why using instance variables in partials is bad
- Use a partial to iterate over a collection, passing in a local
- Use a partial from another controller with a local
Overview
So your team's lead engineer looked over the codebase and asked you to not refer to instance variables in your partials but rather to pass through local variables. That way, your code will be more explicit about its dependencies when it calls the partial.
Also, the lead engineer asked for a couple new features.
The first is that we display all students on the classroom show page instead of singling out the oldest student with a special note. The engineer thinks this isn't very polite.
Second, they also want to add some search functionality so that a user can search for a student by name. They'll type the name in in a form field and we'll use the power of ActiveRecord to find matching data. It's OK if other students with similar names are returned in the search results.
Instructions
-
Refactor the
_form.html.erb
partial to accept the argument to theform_for
helper as a local. You'll also need to change thenew.html.erb
andedit.html.erb
views as well. -
Refactor the
_student.html.erb
partial to pass through each rendered student as a local. -
On the classroom show page, iterate through each classroom's students and display each of them using our
_student.html.erb
partial with locals. -
Create a
_classroom.html.erb
partial to display classroom information on the classroom show page. -
Add in search functionality such that users can type in a student name or fragment of a student name and and see all matching results on the students index page. The results should be displayed by rendering a
students/_student.html.erb
partial. This will require you to do a "fuzzy" or "wildcard" search in the controller in order to create the set of matches. To help you out, you'll want to write a flexibly matching (or "wildcard") query in ActiveRecord that follows the form:Student.where("name LIKE ?", "%M%")
. You should be able to visually test this by visitinghttp://localhost:3000?query="search_text"
. Doing so will mean that you will have aquery
parameter whose data can be fit into aLIKE
query.
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