Edge cases with key transformations

[summera]

Describe the bug

I've noticed a few interesting bugs/edge cases related to transforming keys:

Case 1 - Nested inline associations

Using #transform_keys! does not seem to work on nested inline associations, whereas #transform_keys does. Here's an example. Note that valueCents is still camel case when calling #transform_keys!(:dash).

class MySerializer
  include Alba::Resource

  transform_keys :lower_camel

  many :budget_lines do
    attributes :operating_budget_id

    many :budget_amounts do
      attributes :value_cents
    end
  end
end


> MySerializer.new(object).as_json
=>
{"budgetLines" =>
  [{"operatingBudgetId" => 1,
    "budgetAmounts" => [{"valueCents" => 100}]}]}

> MySerializer.transform_keys!(:dash).new(object).as_json
=>
{"budget-lines" =>
  [{"operating-budget-id" => 1,
    "budget-amounts" => [{"valueCents" => 100}]}]}

Case 2 - transform_keys! side effects remain

Note that the final call to as_json is a mix of dash and camel case. This might be related to inline associations?

> MySerializer.new(object).as_json
=>
{"budgetLines" =>
  [{"operatingBudgetId" => 1,
    "budgetAmounts" => [{"valueCents" => 100}]}]}

> MySerializer.transform_keys!(:dash).new(object).as_json
=>
{"budget-lines" =>
  [{"operating-budget-id" => 1,
    "budget-amounts" => [{"valueCents" => 100}]}]}

> MySerializer.new(object).as_json
=>
{"budgetLines" =>
  [{"operating-budget-id" => 1,
    "budget-amounts" => [{"valueCents" => 100}]}]}

Case 3 - JSONB does not have keys transformed

I have a column with a JSONB array of objects that has snakecase keys. If included in the serializer, I'd like to have those keys transformed as well. Is there a good way to achieve this? Right now, I'm doing the following as a workaround:

  attribute :periods do |object|
    object.periods.map do |p|
      p.deep_transform_keys { |key| transform_key(key) }
    end
  end

To Reproduce

See examples above.

Expected behavior

• Case 1: #transform_keys! expected to propagate to nested relations
• Case 2: #transform_keys! expected to not have side effects beyond using the class returned from it. Do you think it would be possible to pass the key type to the #serialize or #as_json methods if we want to change keys at the time of serialization? Example would be: MySerializer.new(object).as_json(transform_keys: :lower_camel).
• Case 3: It would be nice to be able to transform hash/jsonb attributes

Actual behavior

See examples above.

Environment

• Ruby version: 3.4.4

Thanks in advance for any help!

[okuramasafumi]

@summera Thank you for reporting issues. For case 1 and 2, I think it's a bug. And for case 3, Alba is designed to work with Ruby objects, not with RDB columns, so I cannot come up with a good solution for this case.

Would you like to work on this? If not, I'm going to investigate it.

[summera]

Hey @okuramasafumi, thanks for the response!

And for case 3, Alba is designed to work with Ruby objects, not with RDB columns, so I cannot come up with a good solution for this case.

Just to clarify, I think from Alba's perspective, it would be a matter of dealing with hashes and arrays, not necessarily with database columns. You can see the same behavior with inline hashes and arrays:

class MySerializer
  include Alba::Resource

  transform_keys :lower_camel

  attribute :hash do
    { foo_bar: :baz }
  end

  attribute :array do
    [{ foo_bar: :baz }]
  end
end

=> {"hash" => {foo_bar: :baz}, "array" => [{foo_bar: :baz}]}

In theory, I think it could be handled by using something like Rails' #deep_transform_values? Unless I'm missing something?

Would you like to work on this? If not, I'm going to investigate it.

Please feel free to investigate and thank you! If I'm able to find some time to investigate in the short-term, I'll follow up.

[okuramasafumi]

@summera I cannot find the exact cause of case 1 and 2. This is experimental feature, and it's hard to debug this kind of behavior (that's part of the reasons why it's experimental). so please expect some more time to fix.
I think I can fix case 3 relatively easily, so could you submit another issue for that JSONB problem only? It makes it easy to track progress, and case 3 is different from case 1 and anyway.

[okuramasafumi]

@summera I came up with this case:

class MySerializer
  include Alba::Resource

  transform_keys :lower_camel

  attribute :hash do
    { foo_bar: :baz }
  end

  attribute :deep_nested_array do
    [[[{ foo_bar: :baz }]]]
  end
end

Then, deep_nested_array has a Hash inside, but it's under deep nest. Should this be handled?

[summera]

Then, deep_nested_array has a Hash inside, but it's under deep nest. Should this be handled?

Hey @okuramasafumi, sorry for the delayed reply! I'm not clear on the case you're asking about. Are you asking whether Alba should handle cases where the top-level object is an array or something else? Would you still like me to open a separate ticket?