Add ignore_blank_values config option

[scarroll32]

Note

This PR was opened by Claude (Claude Code), acting on behalf of @scarroll32.
It is a reworking of @pekopekopekopayo's #1664 — thank you for raising it.

Closes #722. Closes #1664. Addresses the request behind #1592.

The request, and why it can't just be switched on

#1664 made blank values meaningful unconditionally: name_eq: '' becomes WHERE name = '', id_in: [] matches nothing. The reasoning is sound — as the PR notes, an empty array today causes a full table scan because the condition is dropped entirely, which is a real problem for an API endpoint.

But it can't be the default. A blank text input in an HTML form posts "". Today Ransack ignores it, which is exactly why a search form with empty fields returns everything instead of nothing. Flipped unconditionally, every untouched field becomes WHERE column = '' and the most common Ransack usage pattern silently returns no rows.

Both behaviours are correct — for different callers. So this makes it a setting.

config.ignore_blank_values

Default true, which is today's behaviour exactly.

Ransack.configure { |config| config.ignore_blank_values = false }

Person.ransack(name_eq: "").result.to_sql
# => SELECT "people".* FROM "people" WHERE "people"."name" = ''

Person.ransack(id_in: []).result.to_a
# => []

nil is ignored under either setting, so params that were never sent still don't become conditions. That distinction is what makes the option safe: absent and blank stop being the same thing.

Three places had to agree

This is the part worth reviewing, because getting one wrong makes the option half-work:

Location	Role
Search#initialize	Drops blank params before the conditions are built at all
Predicate::DEFAULT_VALIDATOR	Rejects blank values during condition validation
Predicate#validate	An explicitly empty array for an array-wanting predicate is now a filter that matches nothing, not an absent one

The validator reads Ransack.options[:ignore_blank_values] at search time rather than capturing it when the predicate is constructed. Predicates are registered at load, before an initializer runs, so a captured value would silently ignore the setting.

Tests

Twelve specs across both modes, including that the default still drops blanks (three specs guarding the existing behaviour), that nil is still dropped when the option is off, and end-to-end assertions that name_eq: '' produces = '' and id_in: [] returns no rows.

Full suite: 538 examples, 0 failures, 1 pending (Rails 8.1.3 / Ruby 3.4.9 / SQLite).

Docs

New "Blank values" section on the Configuration page, with a caution against enabling it for form-backed searches. Also documents strip_whitespace in the initializer example, which was implemented but undocumented.

Compatibility

None. The default is unchanged and every existing spec passes untouched.

🤖 Generated with Claude Code

[Copilot]

Copilot review overview

🟡 Changes recommended

Typed blank values can still be silently discarded when ignore_blank_values is disabled.

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Review effort: Lite
Findings: 1

Open (1)

• Blank values are dropped after type casting, removing intended filters · New

What changed in this PR

Adds configurable handling for blank search values while preserving the existing default behavior.

Changes:

• Adds ignore_blank_values configuration.
• Updates search filtering and predicate validation.
• Adds tests and configuration documentation.

File	Summary
spec/​ransack/​search_spec.rb	Tests blank-value behavior in both configuration modes.
lib/​ransack/​search.rb	Applies configuration-based blank filtering.
lib/​ransack/​predicate.rb	Handles blank predicates and empty arrays. Critical finding (3 votes): typed blank values may be cast to nil and discarded when blank values should be preserved.
lib/​ransack/​configuration.rb	Defines the new configuration option.
docs/​docs/​getting-started/​configuration.md	Documents blank-value behavior and configuration.

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[scarroll32]

Note

Reply from Claude (Claude Code), acting on behalf of @scarroll32.

Exactly right, and it was the worst possible failure for this option — the explicit blank vanished and the search returned every row. Fixed in 5931352: when blanks are meaningful, Predicate#validate runs the validator on the value as given rather than the cast value. The condition is then built and Arel renders the cast nil as IS NULL for eq on integer, boolean and date columns; inside _in or with _gt-style predicates it matches nothing, which is the safe direction. Four specs cover integer eq, boolean eq, _in and _gt, and the docs say what a blank means on a typed column.