Base: read from known_attributes in respond_to_missing?#450
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By including the [ActiveModel::AttributeAssignment][], the `Base` class
can access the [assign_attributes][] method for bulk assignment of
attributes **without** saving them to the server (like through
`Base#update_attributes`).
```ruby
person = Person.new
person.id # => nil
person.name # => nil
person.assign_attributes id: 1, name: "Matz"
person.id # => 1
person.name # => "Matz"
```
Support for versions prior to 7.2.0
---
This commit includes a conditional monkey-patch of the
`_assign_attribute` method when Active Model's version is < 7.2.0:
```ruby
# 7.1.5.2
def _assign_attribute(k, v)
setter = :"#{k}="
if respond_to?(setter)
public_send(setter, v)
else
raise UnknownAttributeError.new(self, k.to_s)
end
end
# 7.2.0
def _assign_attribute(k, v)
setter = :"#{k}="
public_send(setter, v)
rescue NoMethodError
if respond_to?(setter)
raise
else
raise UnknownAttributeError.new(self, k.to_s)
end
end
```
The change is necessary because the [7.1.5.2][] version queries the
instance with `respond_to?`, whereas the [7.2.0][] version skips the
query and sends the method first, falling back to a `NoMethodError`
rescue in case that it doesn't.
[rails#450][] is an alternative to including the monkey patch. If merged,
it'd make `respond_to?` behavior more like `method_missing`, so the
monkey patch would be unnecessary.
[ActiveModel::AttributeAssignment]: https://edgeapi.rubyonrails.org/classes/ActiveModel/AttributeAssignment.html
[assign_attributes]: https://edgeapi.rubyonrails.org/classes/ActiveModel/AttributeAssignment.html#method-i-assign_attributes
[7.1.5.2]: https://github.com/rails/rails/blob/v7.1.5.2/activemodel/lib/active_model/attribute_assignment.rb
[7.2.0]: https://github.com/rails/rails/blob/v7.2.0/activemodel/lib/active_model/attribute_assignment.rb
[rails#450]: rails#450
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method_missing and respond_to_missingknown_attributes in respond_to_missing?
Prior to this commit, the `respond_to_missing?` implementation had a
conditional to supports attributes being able to be written to through
methods "did not respond to" (like `send("#{attr_name}=", value)`), as
well as `?`-suffixed predicate methods.
The `method_missing` implementation has a set of conditionals similar to
`respond_to_missing`, but with subtle variations through checking for an
attribute name's inclusion in `known_attributes` (attributes defined by
the Schema **or** assigned during `Base#load`) rather than the attribute
name's inclusion in `attributes` (the current instance's assigned
values, without any attributes declared in the Schema).
Without the implementation changes, the following tests introduced in
this commit fail:
```
1) Failure:
BaseTest#test_respond_to_known_attributes [test/cases/base_test.rb:972]:
Expected #<Person:0x000000011d0cdcf8 @attributes={}, @prefix_options={}, @persisted=false> (Person) to respond to #name=.
```
This commit changes the `respond_to_missing?` conditional to check for
the presence of the key in `known_attributes` rather than `attributes`
so that instances will respond to `=`-suffixed writers and `?`-suffixed
predicates for attributes that are declared in the resource's Schema
that have not yet been assigned to.
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Prior to this commit, the
respond_to_missing?implementation had aconditional to supports attributes being able to be written to through
methods "did not respond to" (like
send("#{attr_name}=", value)), aswell as
?-suffixed predicate methods.The
method_missingimplementation has a set of conditionals similar torespond_to_missing, but with subtle variations through checking for anattribute name's inclusion in
known_attributes(attributes defined bythe Schema or assigned during
Base#load) rather than the attributename's inclusion in
attributes(the current instance's assignedvalues, without any attributes declared in the Schema).
Without the implementation changes, the following tests introduced in
this commit fail:
This commit changes the
respond_to_missing?conditional to check forthe presence of the key in
known_attributesrather thanattributesso that instances will respond to
=-suffixed writers and?-suffixedpredicates for attributes that are declared in the resource's Schema
that have not yet been assigned to.