Handle scalar rows in CSV export

[Mike Krüger (mkrueger)]

Problem

export --format=csv collected CSV headers only from JSON object properties. Rows whose value is not an object (for example export out.csv --format=csv --query="SELECT VALUE c.id FROM c", or numbers, booleans, null, arrays) were written as empty lines, while the command still reported the exported row count.

Change

• Non-object rows are written to a column with an empty header by default; set COSMOSDB_SHELL_CSV_SCALAR_COLUMN to name it, matching the existing scalar CSV rendering in CommandState.Table.cs (JsonElement.ToString() escaped with CommandState.EscapeCSV).
• Mixed result sets keep both the object property columns and the scalar column, so no row loses data.
• Object-only exports are unchanged.
• docs/commands.md describes the empty default header, environment-variable override, and mixed results. Header collisions produce an error instead of combining values.

Tests in ExportCommandTests cover scalar strings that need escaping, numbers, booleans, null, arrays, object-only rows, mixed rows, and the default/environment-variable lookup.

Examples

CSV output below uses the default ; separator.

1. Scalar-only results

Container documents: {"id":"1"}, {"id":"2"}, {"id":"3"}

export ids.csv --format=csv --query="SELECT VALUE c.id FROM c"

Before (no header, one empty line per row, while the command still reported 3 exported rows):

After:

""
"1"
"2"
"3"

2. Mixed object and scalar results

Container documents:

{"id":"1","address":{"city":"Berlin","zip":"10115"}}
{"id":"2","address":"Hamburg; Hafen"}
{"id":"3","address":{"city":"Munich"}}

export addresses.csv --format=csv --query="SELECT VALUE c.address FROM c"

Before (the string address from document 2 was lost):

"city";"zip"
"Berlin";"10115"
"";""
"Munich";""

After (object columns are kept and the scalar goes into the empty-header column, escaped as usual):

"city";"zip";""
"Berlin";"10115";""
"";"";"Hamburg; Hafen"
"Munich";"";""

[Copilot]

Copilot review overview

🟢 Approval recommended

The targeted implementation matches existing rendering behavior and is adequately documented and tested.

Review effort: Balanced
Findings: None

What changed in this PR

Adds CSV export support for scalar and mixed query results.

Changes:

• Writes non-object rows to a value column.
• Preserves object-only behavior and supports mixed rows.
• Adds documentation and comprehensive tests.

File	Description
docs/​commands.md	Documents scalar and mixed CSV output.
ExportCommand.cs	Adds scalar-value column generation.
ExportCommandTests.cs	Covers scalar, object, array, and mixed rows.

---

💡 Add a code-review agent skill or configure MCP servers for context-aware, tailored reviews. Learn more in the docs.

[github-code-quality]

Code Coverage Overview

Languages: C#

C# / code-coverage/dotnet

The overall line coverage in commit 754d082 in the dev/mkrueger/fix-csv... branch is 65%. The line coverage in commit 6992beb in the main branch is 66%.

Show a line coverage summary of the most impacted files.

File	main 6992beb	dev/mkrueger/fix-csv... 754d082	+/-
D:\a\CosmosDBSh...akeDbCommand.cs	92%	38%	-54%
D:\a\CosmosDBSh...reateCommand.cs	78%	26%	-52%
D:\a\CosmosDBSh...ainerCommand.cs	85%	35%	-50%
D:\a\CosmosDBSh...urceProvider.cs	62%	33%	-29%
D:\a\CosmosDBSh...ceOperations.cs	20%	3%	-17%
D:\a\CosmosDBSh...sourceFacade.cs	27%	15%	-12%
D:\a\CosmosDBSh...ubscriptions.cs	89%	86%	-3%
D:\a\CosmosDBSh...osmosCommand.cs	42%	40%	-2%
D:\a\CosmosDBSh...xportCommand.cs	62%	65%	+3%
D:\a\CosmosDBSh...mportCommand.cs	46%	50%	+4%

---

_{Updated October 02, 2026 08:09 UTC}

[Copilot]

Copilot review overview

🟡 Changes recommended

The implemented empty default header contradicts the documented value column contract, and the environment-variable path lacks direct coverage.

Review effort: Balanced
Findings: 1

Open (1)

• Add coverage for default and configured scalar column lookup · New

[Copilot]

Copilot review overview

🟢 Approval recommended

The implementation, documentation, localization catalog, and focused regression coverage are consistent and complete.

Review effort: Balanced
Findings: None

Resolved since last review (1)

• Add coverage for default and configured scalar column lookup