- Fix typo
- Adjust output example to other example's format

[ci skip]

This will keep the behavior of an application with the defaults of a 4.2
or 5.0 application behaving the same when upgrading to 5.2.

When `form_with` was introduced we disabled the automatic
generation of ids that was enabled in `form_for`. This usually
is not an good idea since labels don't work when the input
doesn't have an id and it made harder to test with Capybara.

You can still disable the automatic generation of ids setting
`config.action_view.form_with_generates_ids` to `false.`

This basically reverts c4d1a4ef

Add back a bit about a resource oriented style of routing.

[ci skip]

The `@` ivar format doesn’t work with RDoc's `+` code formatting; needs `<tt>`.

[ci skip]

FormHelper includes FormTagHelper so we don't need to define two methods

Also make sure file_field doesn't mutate the original options passed in.

This reverts commit 3420a145, reversing
changes made to afb66a5a.

* Allow a default value to be declared for class_attribute

* Convert to using class_attribute default rather than explicit setter

* Removed instance_accessor option by mistake

* False is a valid default value

* Documentation

Allows users to not have remote forms by default, since there's
more JS harness, e.g. bundling rails-ujs, otherwise.

Also don't skip creating defaults file anymore. Sprockets isn't the only new config.

Effectively treat nil values as "auto", e.g. whatever a form helper
chooses to interpret it as.

But treat an explicitly assigned false value as disabling.

Replace `FormOptionHelper` to `FormOptionsHelper`.

Since it affects the entire form, should not mutate `object_name` of class.

Fixes #26931

Ensure the support works like form_with.

Has the handy effect of making the initial examples in the form_with
docs work too.

Had to do some finagling such that form_with's without a scope didn't
wrap their names in braces ala `[title]`.

Remote is gone, long live local.

By using `except` any option provided to `form_with` would become an html
attribute unless explicitly opted out. This proved annoying when adding
new internal keys in the options hash and seeing them pop up in the html
output.

Prevent this by inverting the `except` to `slice` out the keys we want to
allow becoming html attributes, like id and class.

Fixes that the following ERB template would result in invalid HTML
output:

    <%= form_with model: Post.new, local: true do |form| %>
    <% end %>

Specifically, the resulting form tag would have a spurious `remote`
attribute:

    <form remote="false" ...>

Continuing 67f81cc7 where we decided not to output ids
by default in the new form helpers.

Went with @dhh's suggestion of just requiring ids on
fields being labelled:
https://github.com/rails/rails/issues/25197#issuecomment-231797117

Seems okay enough.

Follow up to #26976.

* Add form_with to unify form_tag/form_for.

`form_tag` and `form_for` serve very similar use cases. This
PR unifies that usage such that `form_with` can output just
the opening form tag akin to `form_tag` and can just work with
a url, for instance.

`form_with` by default doesn't attach class or id to the form —
removing them on fields is moved out to a default revisiting PR later.

Ported over old tests where applicable to ensure maximum coverage,
but left some commented out because they don't yet apply (e.g.
`fields_for` later being replaced by `fields`).

[ Kasper Timm Hansen & Marek Kirejczyk ]

* Add fields DSL method.

Strips `_for` and requires models passed as a keyword argument.

* Document form_with.

Graft the `form_for` docs: rewrite, revise and expand where
needed.

Also test that a `format` isn't used when an explicit URL
is passed.

* Enable remote by default.

Brand new world! Forms submit via XHRs by default, woah.

* Invert `include_id` to `skip_id`.

`skip_id: true` reads better than `include_id: false` (since the
`include_id` default is true).

* Invert `remote` to `local`.

Since forms are remote by default, the option name makes more sense
as `local: true`.

* Invert `enforce_utf8` to `skip_enforcing_utf8`.

* Refer to the brand spanking new rails-ujs.

Soon to be bundled in Rails proper, so jquery-ujs is out.

* Make `form_with` a bit more composed.

The flow is still not quite what it should be because the legacy
methods and these new ones pull at opposite ends.

Lots of options have been renamed, so now the new pieces don't fit
in so well.

I'll try to work on this in later commits after this PR (it's likely
there's a much better way to structure this whole part of Action View).

add `# Let's say that @user.receive_newsletter returns "no":` for `def radio_button(object_name, method, tag_value, options = {})`.
fix `# Let's say that @user.category returns "no":` to `# Let's say that @user.receive_newsletter returns "no":`