Soft delete

WithSoftDeletion(fn) turns a physical DELETE into an UPDATE of selected fields. The "mark, don't drop" pattern — useful to preserve data and keep foreign keys intact.

Setup

.Columns(func(m *User, c *gerpo.ColumnBuilder[User]) {
    c.Field(&m.ID)
    c.Field(&m.DeletedAt).OmitOnInsert()
}).
WithSoftDeletion(func(m *User, b *gerpo.SoftDeletionBuilder[User]) {
    b.Field(&m.DeletedAt).SetValueFn(func(ctx context.Context) any {
        t := time.Now().UTC()
        return &t
    })
}).
WithQuery(func(m *User, h query.PersistentHelper[User]) {
    h.Where().Field(&m.DeletedAt).EQ(nil)
})

Three required pieces:

1. Marker column (DeletedAt). Typically nullable — *time.Time. Add OmitOnInsert so it can't be accidentally written at INSERT time.
2. WithSoftDeletion — describes the value to write on "delete". The function runs on every Delete call and receives the context (useful for user/clock/tenant).
3. WithQuery with a filter — so soft-deleted records don't leak into SELECTs. Without it they show up in listings.

SetValueFn return type

The returned value must match the field type — for *time.Time return *time.Time, not time.Time. Build() runs a type probe: each SetValueFn is invoked once with context.Background() and the returned value is checked against the field type. A mismatch (or a panic from inside the callback) is reported from Build() rather than crashing on the first soft Delete() call.

This is not a full compile-time check — the callback body still runs at repo-build time, and if it branches on ctx values (ctx.Value(tenantKey)) that context.Background() does not carry, the probe exercises a different path than production. Keep SetValueFn bodies free of ctx-dependent branches when possible, or accept that the probe only catches the common ctx=Background case.

How it works

repo.Delete(ctx, …) executes

UPDATE users SET deleted_at = ? WHERE …

instead of DELETE FROM users WHERE …. It returns the UPDATE's RowsAffected. If zero rows match, it returns ErrNotFound.

Restoration

There's no dedicated API — restore a row with a direct UPDATE bypassing the repo:

UPDATE users SET deleted_at = NULL WHERE id = ?;

Alternatively, you can run an extra repo.Update with Only(&m.DeletedAt) and a nil value in the model — but that bypasses the persistent WHERE, so it only works when the repo's structure allows it.

Multiple marker fields

SoftDeletionBuilder supports multiple Field calls — all of them will be updated on soft-delete:

WithSoftDeletion(func(m *User, b *gerpo.SoftDeletionBuilder[User]) {
    b.Field(&m.DeletedAt).SetValueFn(now)
    b.Field(&m.DeletedBy).SetValueFn(userFromCtx)
})