Validates that root where predicates can all be satisfied.

This catches impossible filters.

Examples

Bad:

from(Post, as: :post)
|> where([post: p], p.status == ^:draft)
|> where([post: p], p.status == ^:published)

Why this is bad:

No row can satisfy both equality predicates for the same field. The query is guaranteed to return no rows, which usually means a filter was composed incorrectly.

Better:

from(Post, as: :post)
|> where([post: p], p.status in ^[:draft, :published])

Why this is better:

The allowed values are represented in one satisfiable predicate.

Bad:

from(Post, as: :post)
|> where([post: p], p.sequence == ^1)
|> where([post: p], p.sequence == ^2)

Notes

This check is intentionally narrow. It evaluates supported root where predicates and ignores fragments, subqueries, non-root bindings, and most arbitrary expressions.

The check is intentionally narrow. It evaluates root schema fields and only trusts direct ==, in, and is_nil predicates in AND where expressions. Ecto.Enum fields are normalized through the schema enum mapping. Non-enum fields only compare simple literal values that already match the schema field type. or_where and or expressions are handled as separate branches and only rejected when every branch is statically unsatisfiable and at least one branch has a true predicate conflict. Fragments, subqueries, and non-root bindings are ignored. Empty in candidate lists can make a branch unsatisfiable, but standalone empty in issues are intentionally left to Bylaw.Ecto.Query.Checks.EmptyInPredicates.

Options

• :validate - explicit false disables the check. Defaults to true.

Usage

Add this module to the explicit check list passed through Bylaw.Ecto.Query. See Bylaw.Ecto.Query for the full Ecto.Repo.prepare_query/3 setup.