Add Provide Fake Form Helper To Controllers as a Rails TIL

README.md

@@ -10,7 +10,7 @@ pairing with smart people at Hashrocket.
 
 For a steady stream of TILs, [sign up for my newsletter](https://crafty-builder-6996.ck.page/e169c61186).
 
-_1646 TILs and counting..._
+_1647 TILs and counting..._
 
 See some of the other learning resources I work on:
 - [Get Started with Vimium](https://egghead.io/courses/get-started-with-vimium~3t5f7)
@@ -1099,6 +1099,7 @@ If you've learned something here, support my efforts writing daily TILs by
 - [Prefer select_all Over execute For Read Queries](rails/prefer-select-all-over-execute-for-read-queries.md)
 - [Pretend Generations](rails/pretend-generations.md)
 - [Prevent Writes With A Sandboxed Rails Console](rails/prevent-writes-with-a-sandboxed-rails-console.md)
+- [Provide Fake Form Helper To Controllers](rails/provide-fake-form-helper-to-controllers.md)
 - [Query A Single Value From The Database](rails/query-a-single-value-from-the-database.md)
 - [Read In Environment-Specific Config Values](rails/read-in-environment-specific-config-values.md)
 - [Read-Only Models](rails/read-only-models.md)

rails/provide-fake-form-helper-to-controllers.md

@@ -0,0 +1,40 @@
+# Provide Fake Form Helper To Controllers
+
+I'm rendering a partial from a turbo stream. The partial is meant to be
+rendered within a Rails form object because it contains an input element that
+needs to reference the form object. The problem is that from the controller
+that is streaming the partial, there is no
+[FormBuilder](https://api.rubyonrails.org/v6.1.0/classes/ActionView/Helpers/FormBuilder.html)
+object.
+
+One way to get around this that I've borrowed from [Justin
+Searls](https://justin.searls.co/posts/instantiate-a-custom-rails-formbuilder-without-using-form_with/)
+is with a `FauxFormHelper`.
+
+```ruby
+module FauxFormHelper
+  FauxFormObject = Struct.new do
+    def errors
+    end
+
+    def method_missing(...)
+    end
+
+    def respond_to_missing?(...)
+      true
+    end
+  end
+
+  def faux_form
+    @faux_form ||= ActionView::Helpers::FormBuilder.new(
+      nil,
+      FauxFormObject.new,
+      self,
+      {}
+    )
+  end
+end
+```
+
+This module defines and exposes a `faux_form` object that controllers and views
+can access. Then my partial can recieve that form object as a parameter.