Field Enhancements and Select Bind Fix

[StrangeYear]

• Do only one thing
• Non breaking API changes
• Tested

What did this pull request do?

This pull request enhances gorm/gen field expression capabilities and fixes an issue related to bind variable index generation in parameterized SELECT expressions. It includes the following updates:

• Add Coalesce function to field expressions.
• Add ILike / NotILike helpers for PostgreSQL.
• Add Filter function to support PostgreSQL FILTER (WHERE ...) syntax in aggregate expressions.
• Fix incorrect bind index generation when using parameterized expressions inside Select(...).

New Features

1. Coalesce

Adds support for SQL COALESCE in field.Expr:

u.Name.Coalesce("unknown")

Generates:

COALESCE("name", ?)

2. ILike / NotILike

Adds PostgreSQL case-insensitive pattern matching:

u.Name.ILike("%john%")
u.Name.NotILike("%test%")

Generates:

"name" ILIKE ?
"name" NOT ILIKE ?

3. Filter (PostgreSQL aggregate filter)

Adds support for conditional aggregation:

u.ID.Count().Filter(u.Age.Gt(18))

Generates:

COUNT("id") FILTER (WHERE "age" > ?)

This allows clean construction of conditional aggregate expressions without falling back to raw SQL.

Bug Fix

Previously, when multiple field.Expr values containing bind variables were passed into Select(...), each expression was built using a new gorm.Statement. This caused bind indexes to restart from $1 for every expression (PostgreSQL), producing invalid SQL such as:

SELECT $1, $1

instead of:

SELECT $1, $2

This PR fixes the issue by preserving bind index offsets across select expressions while still preventing SQL accumulation between statements.

The fix:

• Ensures continuous and correct bind index generation
• Does not change any public API
• Does not affect existing users who do not use parameterized select expressions
• Corrects previously invalid SQL behavior

This change is considered a bug fix rather than a breaking change.

User Case Description

This PR enables advanced SQL construction in gorm/gen:

1. Conditional aggregation (PostgreSQL):

Select(
    u.ID.Count().Filter(u.Status.Eq("active")),
)

2. Case-insensitive search:

Where(u.Name.ILike("%john%"))

3. Null fallback handling:

Select(u.Nickname.Coalesce(u.Name))

4. Parameterized expressions inside Select:

Select(
    field.Expr("?", 1),
    field.Expr("?", 2),
)

Now correctly generates:

SELECT $1, $2

Compatibility

• No public API changes
• No breaking behavior
• Existing non-parameterized Select usage unaffected
• Only fixes incorrect bind index behavior when parameters are used in select expressions

[propel-code-bot]

LGTM, ship it! 🚢

Details

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[propel-code-bot]

These helpers gracefully downgrade to standard LIKE/NOT LIKE semantics or the base aggregate form on non-PostgreSQL backends, and the select-expression plumbing now preserves the running bind offset while preventing SQL accumulation between statements.

Affected Areas

• field/clause.go
• field/generics.go
• field/expr.go
• do.go

This summary was automatically generated by @propel-code-bot

[propel-code-bot]

LGTM, ship it! 🚢

Details

Why was this auto-approved?

✅ APPROVED: No issues detected.

Dismissing previous approval: 1 new comment(s) require attention based on Default policy

[propel-code-bot]

LGTM, ship it! 🚢

Details

Why was this auto-approved?

✅ APPROVED: No issues detected.