Fix collection partial leaking fields between iterations (#64)#65
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jujustayfly wants to merge 1 commit into
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Fix collection partial leaking fields between iterations (#64)#65jujustayfly wants to merge 1 commit into
jujustayfly wants to merge 1 commit into
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`PbbuilderTemplate#_render_collection_with_options` allocated a single sub-message and reused it across every iteration of the partial, so any field not actively rewritten on a given iteration carried over from the previous one. In particular: - Repeated message fields written via `pb.field collection do |x| ... end` accumulated across iterations because `_append_repeated` pushes onto the shared message. - Conditionally-written fields leaked the previous element's value into elements that took the silent branch. Reset the working message on the shared `pb` between iterations inside `Pbbuilder::CollectionRenderer#build_rendered_template`, so each render starts with a clean sub-message of the right type. This brings the `partial:`/`collection:` shorthand to parity with the per-element allocation already done by manual iteration through `_append_repeated`. Adds a `_reset_message` helper on `Pbbuilder` (since the class inherits from `BasicObject` and doesn't expose `instance_variable_set`) plus two regression tests covering both leak shapes. Co-authored-by: Cursor <cursoragent@cursor.com>
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Summary
Fixes #64.
PbbuilderTemplate#_render_collection_with_optionsallocates one sub-message and reuses it for every iteration of the partial, so fields that aren't actively rewritten leak from the previous element. Two visible shapes:pb.field collection do |x| ... endinside the partial routes through_append_repeated, whichpushes onto the shared message's repeated field, so each iteration sees all prior elements.if/elsifthat writes a field only on some branches inherits the previous element's value on the silent branch.Manual iteration (
pb.field coll.each do |x| ... endat the top level) is unaffected because_append_repeatedalready allocates a fresh sub-message per element.Fix
Reset the working message on the shared
pbbetween iterations insidePbbuilder::CollectionRenderer#build_rendered_template. After snapshotting the body for the just-rendered element, swap@messagefor a fresh sub-message of the right type viapb_parent.new_message_for(field). The first iteration is already clean (initialized in_render_collection_with_options), so every iteration now starts from a fresh message.This brings the
partial:/collection:shorthand to parity with the per-element allocation manual iteration already does in_append_repeated— no extra wrapper allocation, just one extra protobuf message per element (same cost as the workaround documented in the issue).A small
_reset_message(message)helper was added toPbbuilderbecause the class inherits fromBasicObjectand doesn't exposeinstance_variable_set(calling it would route throughmethod_missing→set!and raise "Unknown field").