stdlib: implement driver.RowsColumnScanner for Go 1.27#2542
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Go 1.27 adds the driver.RowsColumnScanner interface, which lets a driver scan a column directly into the user's destination. This means stdlib users can now scan PostgreSQL arrays, ranges, multiranges, and other pgtype-aware values directly into Go slices and pgtype types without the *pgtype.Map.SQLScanner adapter. ScanColumn first tries m.Scan for pgx-native handling, then falls back to the newly public sql.ConvertAssign on a driver.Value produced by the column codec. The fallback preserves database/sql conversion semantics (e.g., scanning a binary bool into *string yields "true"/"false") for destinations pgx does not recognize. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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The RowsColumnScanner interface signatures changed between the proposal draft and the released Go 1.27 RC1. Update ScanColumn to take the leading driver.ScanContext parameter and thread it through to sql.ConvertAssign, which also gained scanCtx as its first argument. Without these, *Rows did not satisfy driver.RowsColumnScanner and database/sql silently fell back to the old Next path. Add a compile-time assertion so future signature drift fails the build. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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I've updated this PR for what finally landed in Go 1.27 RC1. Should be ready to go, but extra eyes and testers would be great. |
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June 21, 2026 02:34
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Go 1.27 adds the driver.RowsColumnScanner interface, which lets a driver scan a column directly into the user's destination. This means stdlib users can now scan PostgreSQL arrays, ranges, multiranges, and other pgtype-aware values directly into Go slices and pgtype types without the *pgtype.Map.SQLScanner adapter.
ScanColumn first tries m.Scan for pgx-native handling, then falls back to the newly public sql.ConvertAssign on a driver.Value produced by the column codec. The fallback preserves database/sql conversion semantics (e.g., scanning a binary bool into *string yields "true"/"false") for destinations pgx does not recognize.