Skip SQLite generated columns in generate entity

[JMLX42]

PR Info

• Closes: sea-orm-cli generate entity emits SQL generated columns (VIRTUAL/STORED) as writable fields #3094
• Related: fix generated columns not being discovered sea-schema#161, Column extra causes sync to add column again #2995

Bug Fixes

• sea-orm-cli generate entity no longer reverse-generates SQLite generated columns (GENERATED ALWAYS AS (...) VIRTUAL/STORED) as ordinary, writable entity fields.

Description

SQLite generated columns became discoverable when discovery switched from PRAGMA table_info to PRAGMA table_xinfo in SeaQL/sea-schema#161 — a correct fix for schema sync (#2995), where generated columns were previously invisible and sync kept re-issuing ALTER TABLE ... ADD COLUMN.

As a side effect, generate entity consumes the same discovery and now emits these columns as plain fields:

#[sea_orm(column_type = "Text", nullable)]
pub pixels: Option<i32>,

Because there is no marker distinguishing them, they land in the derived ActiveModel. Any Model::into_active_model() round-trip then includes them in INSERT/UPDATE, and SQLite rejects it:

cannot INSERT into generated column "pixels"
cannot UPDATE generated column "pixels"

Generated columns are read-only at the storage layer, so they should not be reverse-generated as writable columns. In the Entity-First workflow they are declared with #[sea_orm(extra = "GENERATED ALWAYS AS (...) VIRTUAL")], not produced by reverse codegen.

Changes

• Add discard_generated_columns() in sea-orm-cli's generate command. In the SQLite branch, each discovered table is passed through it before TableDef::write(), removing columns whose ColumnVisibility is GeneratedVirtual or GeneratedStored.
• Discovery itself is untouched, so schema sync keeps seeing generated columns and the Column extra causes sync to add column again #2995 fix is preserved — only the reverse-codegen path drops them.
• Unit test test_discard_generated_columns covering both VIRTUAL and STORED columns and confirming ordinary columns are preserved in order.

This restores the pre-rc.34 generate entity behavior for generated columns. A faithful round-trip (emitting #[sea_orm(extra = "GENERATED ...")] and marking the field read-only) would be a larger, cross-crate change — table_xinfo does not return the generation expression — and is noted as a follow-up in #3094.

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_{Authored by an AI agent (Claude Code, Anthropic), reviewed by a maintainer of a downstream project that hit this on a routine sea-orm-cli bump.}