rmosolgo / rmosolgo/graphql-ruby
Fields with lazy results aren't resolved inside directive context
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- Ruby
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Description
Describe the bug
If you have a field that is resolved lazily, e.g. using a GraphQL::Batch::Loader, and that field is selected in a query using a directive which applies to the field, the field will be resolved outside of the directive's scope (outside of the yield of the directive's resolve).
Say you're using a gem with a class method that's given a block and that method sets/reverts a class variable before/after the block is called. Then you write a directive that passes resolve's block into that gem's class method as its block. Given a lazy field that uses the class variable, that field will be resolved using the "after" value instead of the "during" value.
Versions
graphql version: 2.3.7
rails (or other framework): N/A
other applicable versions (graphql-batch, etc): graphql-batch 0.6.0
GraphQL schema
class Attributed
class << self
attr_reader :attr
def with_attribute(attr)
previous_attr = @attr
@attr = attr
yield
ensure
@attr = previous_attr
end
end
end
class TestLoader < GraphQL::Batch::Loader
def perform(keys)
keys.each { fulfill(_1, Attributed.attr) }
end
end
class TestSchema < GraphQL::Schema
class TestQuery < GraphQL::Schema::Object
field :lazy_value, String
def lazy_value
TestLoader.for.load(nil)
end
field :value, String
def value
Attributed.attr
end
end
class WithAttribute < GraphQL::Schema::Directive
locations(GraphQL::Schema::Directive::QUERY)
def self.resolve(*, &block)
Attributed.with_attribute("red", &block)
end
end
query(TestQuery)
directives(WithAttribute)
use(GraphQL::Batch)
end
GraphQL query
query @withAttribute {
value
lazyValue
}
{
"data": {
"value": "red",
"lazyValue": nil
}
}
Steps to reproduce
Run the query above using the provided schema and classes
Expected behavior
Both value and lazyValue resolve to red
Actual behavior
lazyValue resolves to nil because it's outside of the withAttribute directive scope when it gets resolved and so Attributed.with_attributed has reverted to its previous attr value.
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start by running the provided TestSchema, TestLoader, WithAttribute directive, and query to reproduce the difference between value and lazyValue. Trace directive resolve and lazy field execution, then add a regression test showing both fields resolve to red while the directive scope is active.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- graphql, ruby
- Domain
- api, backend
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 45/100