Add -f codepage flag for input/output encoding by dlevy-msft-sql · Pull Request #627 · microsoft/go-sqlcmd

dlevy-msft-sql · 2026-01-25T03:10:02Z

Summary

Implements the -f flag from ODBC sqlcmd for specifying input and output file code pages.

Changes

cmd/sqlcmd/sqlcmd.go: Added CodePage and ListCodePages fields, -f/--code-page flag, validation, and runtime application
pkg/sqlcmd/codepage.go: Comprehensive codepage support with parsing and encoding conversion
pkg/sqlcmd/codepage_test.go: Unit tests for codepage parsing and supported encodings
pkg/sqlcmd/commands.go: Updated :R command to respect codepage settings when reading files
pkg/sqlcmd/sqlcmd.go: Added CodePage field to Sqlcmd struct
cmd/sqlcmd/sqlcmd_test.go: Command line argument tests for valid and invalid codepage values
README.md: Documentation with format examples

Usage

# Single codepage for both input and output
sqlcmd -S server -f 65001 -i script.sql -o results.txt

# Different codepages for input and output
sqlcmd -S server -f i:1252,o:65001 -i windows_script.sql -o utf8_results.txt

# List all supported codepages
sqlcmd --list-codepages

Supported Codepages

Unicode: 65001 (UTF-8), 1200 (UTF-16LE), 1201 (UTF-16BE)
Windows: 874, 1250-1258
OEM/DOS: 437, 850, etc.
ISO-8859: 28591-28606
CJK: 932 (Shift-JIS), 936 (GB2312), 949 (Korean), 950 (Big5)
EBCDIC: 37, 1047, 1140

Testing

All existing tests pass
Added command line argument parsing tests
Added unit tests for codepage parsing and validation

Improves ODBC sqlcmd compatibility.

- Add -f/--code-page flag with ODBC-compatible format parsing - Support 50+ codepages: Unicode, Windows, OEM/DOS, ISO-8859, CJK, EBCDIC, Macintosh - Apply input codepage in IncludeFile() for :r command - Apply output codepage in outCommand() for :OUT file writes - Add --list-codepages flag to display all supported codepages - Add comprehensive unit tests for parsing and encoding lookup

Copilot

Pull request overview

Adds ODBC sqlcmd-compatible -f/--code-page support to control input/output file encodings (plus --list-codepages) for improved interoperability.

Changes:

Introduces codepage parsing/validation and a mapping from Windows codepages to Go encodings.
Applies configured codepages when reading -i / :R files and when writing -o / :OUT / :ERROR outputs.
Adds CLI argument tests, unit tests for codepage parsing/lookup, and README documentation.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
`cmd/sqlcmd/sqlcmd.go`	Adds `-f/--code-page`, `--list-codepages`, validation, and wiring into runtime `Sqlcmd` configuration.
`cmd/sqlcmd/sqlcmd_test.go`	Adds CLI parsing/validation test cases for the new flags.
`pkg/sqlcmd/codepage.go`	Implements `ParseCodePage`, `GetEncoding`, and `SupportedCodePages`.
`pkg/sqlcmd/codepage_test.go`	Adds unit tests for parsing and encoding lookup.
`pkg/sqlcmd/commands.go`	Applies output codepage transforms in `:OUT` and `:ERROR`.
`pkg/sqlcmd/sqlcmd.go`	Applies input codepage transforms (or BOM-based auto-detect fallback) when including files.
`README.md`	Documents `-f` usage and `--list-codepages`.

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pkg/sqlcmd/commands.go

pkg/sqlcmd/codepage_test.go

pkg/sqlcmd/commands.go

Copilot

Pull request overview

Copilot reviewed 7 out of 7 changed files in this pull request and generated 5 comments.

pkg/sqlcmd/sqlcmd.go

pkg/sqlcmd/commands.go

pkg/sqlcmd/sqlcmd.go

pkg/sqlcmd/codepage_test.go

pkg/sqlcmd/codepage.go

- Fix nil encoding panic in errorCommand when OutputCodePage is 65001 (UTF-8) - Close file handle in outCommand when GetEncoding returns an error - Handle close error properly in errorCommand - Apply UTF-8 BOM stripping when input codepage is 65001 - Fix test subtest names to use strconv.Itoa instead of string(rune)

Copilot

Pull request overview

Copilot reviewed 7 out of 7 changed files in this pull request and generated 5 comments.

pkg/sqlcmd/sqlcmd.go

pkg/sqlcmd/codepage.go

pkg/sqlcmd/commands.go

Copilot

Pull request overview

Copilot reviewed 7 out of 7 changed files in this pull request and generated 2 comments.

pkg/sqlcmd/commands.go

- Use localizer.Errorf for all user-facing error messages - Fix UTF-16 BOM handling using ExpectBOM for input decoding - Add transformWriteCloser to properly close underlying file handles - Use transformWriteCloser in outCommand and errorCommand for both UnicodeOutputFile and CodePage transforms to prevent file handle leaks - Add integration tests for output/error codepage encoding

Use strconv.Itoa instead of %d to avoid locale-specific thousands separators in error message.

Copilot

Pull request overview

Copilot reviewed 8 out of 8 changed files in this pull request and generated 2 comments.

pkg/sqlcmd/codepage.go

pkg/sqlcmd/sqlcmd.go

- Create codepageRegistry map as single source of truth for codepages - GetEncoding() now uses the registry instead of switch statement - SupportedCodePages() now generates list from registry - Removes duplicate codepage definitions between the two functions - Sort SupportedCodePages result by codepage number for consistency

- Verify all returned codepages are valid in GetEncoding - Ensure results are sorted by codepage number - Check well-known codepages are present

Copilot

Pull request overview

Copilot reviewed 8 out of 8 changed files in this pull request and generated 3 comments.

pkg/sqlcmd/codepage.go

pkg/sqlcmd/sqlcmd.go

cmd/sqlcmd/sqlcmd.go

Copilot

Pull request overview

Copilot reviewed 8 out of 8 changed files in this pull request and generated 3 comments.

Copilot · 2026-01-25T23:40:24Z

pkg/sqlcmd/codepage.go

+			settings.OutputCodePage = cp
+		}
+	}
+


ParseCodePage currently accepts inputs that contain no actual codepage value (e.g. "," or only whitespace) and returns a non-nil CodePageSettings with both InputCodePage/OutputCodePage left as 0. That silently disables codepage handling even though the user supplied -f. Consider detecting this case (arg != "" but neither codepage parsed) and returning an error (and add a unit test for it).

Suggested change

// If a non-empty argument was provided but no codepage was parsed,

// treat this as an error rather than silently disabling codepage handling.

if arg != "" && settings.InputCodePage == 0 && settings.OutputCodePage == 0 {

return nil, localizer.Errorf("invalid codepage: %s", arg)

}

Copilot · 2026-01-25T23:40:24Z

pkg/sqlcmd/sqlcmd.go

+			// UTF-8 codepage: still apply BOM stripping
+			utf8bom := unicode.BOMOverride(unicode.UTF8.NewDecoder())
+			reader = transform.NewReader(f, utf8bom)
+		}
+	} else {
+		// Default: auto-detect BOM for UTF-16, fallback to UTF-8


The comment "UTF-8 codepage: still apply BOM stripping" is a bit misleading: unicode.BOMOverride will also switch decoders when it sees a UTF-16 BOM (not just strip a UTF-8 BOM). If the intent is broader BOM auto-detection, consider updating the comment; if the intent is only stripping a UTF-8 BOM, consider using a transformer that only removes the UTF-8 BOM.

Suggested change

// UTF-8 codepage: still apply BOM stripping

utf8bom := unicode.BOMOverride(unicode.UTF8.NewDecoder())

reader = transform.NewReader(f, utf8bom)

}

} else {

// Default: auto-detect BOM for UTF-16, fallback to UTF-8

// UTF-8 codepage: use BOMOverride to strip UTF-8 BOM and auto-detect UTF-16 BOMs, defaulting to UTF-8 otherwise

utf8bom := unicode.BOMOverride(unicode.UTF8.NewDecoder())

reader = transform.NewReader(f, utf8bom)

}

} else {

// Default: auto-detect BOMs (UTF-8/UTF-16) and decode accordingly, falling back to UTF-8 when no BOM is present

Copilot · 2026-01-25T23:40:25Z

pkg/sqlcmd/commands_test.go

+		name           string
+		codepage       int
+		expectedBytes  []byte
+		inputText      string
+		skipOnEncError bool


The skipOnEncError field in this test table is never used. Please remove it or use it (e.g., to skip assertions when a target encoding can’t represent the input text), to avoid dead/misleading test code.

Suggested change

name string

codepage int

expectedBytes []byte

inputText string

skipOnEncError bool

name string

codepage int

expectedBytes []byte

inputText string

dlevy-msft-sql · 2026-01-26T00:14:51Z

PR replaced by #638

dlevy-msft-sql requested a review from Copilot January 25, 2026 03:21

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dlevy-msft-sql added this to the ODBC SQLCMD Interchangeability milestone Jan 25, 2026

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Merge branch 'main' into round-out-part2

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Fix ineffectual assignment lint error

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dlevy-msft-sql added 2 commits January 25, 2026 13:26

Fix locale-specific number formatting in codepage error

2a14b75

Use strconv.Itoa instead of %d to avoid locale-specific thousands separators in error message.

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test: add TestSupportedCodePages to verify registry consistency

065b1f4

- Verify all returned codepages are valid in GetEncoding - Ensure results are sorted by codepage number - Check well-known codepages are present

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dlevy-msft-sql mentioned this pull request Jan 25, 2026

feat: implement -R and -f flags for regional settings and codepage #628

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dlevy-msft-sql added the sqlcmd switch switch in existing sqlcmd label Jan 25, 2026

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dlevy-msft-sql mentioned this pull request Jan 26, 2026

feat: add -f codepage flag for input/output encoding #638

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dlevy-msft-sql deleted the round-out-part2 branch February 5, 2026 21:41

dlevy-msft-sql restored the round-out-part2 branch February 5, 2026 21:41

+	// If a non-empty argument was provided but no codepage was parsed,
+	// treat this as an error rather than silently disabling codepage handling.
+	if arg != "" && settings.InputCodePage == 0 && settings.OutputCodePage == 0 {
+		return nil, localizer.Errorf("invalid codepage: %s", arg)
+	}

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