haskell-beam/beam

onConflictUpdateSetWhere has wrong type?

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#644 opened on Nov 7, 2022

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Description

I noticed that this function's type is

onConflictUpdateSetWhere :: Beamable table
  => (forall s. table (QField s) -> table (QExpr be s) -> QAssignment be s)
  -> (forall s. table (QField s) -> table (QExpr be s) -> QExpr be s Bool)
  -> SqlConflictAction be table

The first callback controls the assignments for the ON CONFLICT UPDATE clause, while the second callback controls the WHERE. It has two arguments,

  • table (QField s) -- this represents the existing table
  • table (QExpr be s) -- this represents the "excluded" row, i.e. the one that would have been inserted if there were no conflict.

I'm confused about the first argument. Shouldn't it be a table (QExpr be s) instead of table (QField s)? If the purpose is to use it to write a QExpr be s Bool, then it seems wrong for it to have this QField type (unless there's a conversion function I'm missing).

I'm also comparing it with functions like conflictingFieldsWhere, which also use the table (QExpr be s) type.

Please let me know if I'm missing something obvious :)

Contributor guide

Research direction
Inspect the type signature of onConflictUpdateSetWhere and compare with conflictingFieldsWhere. Check if there is a conversion function from QField to QExpr that should be applied, or if the type is indeed incorrect. Trace usage in the codebase to see how the first argument is used.
Tech stack
haskell
Domain
database
Issue type
Bug
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2
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1-3 hours
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Clear
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Haskell
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60