feat: Json data type

[matthewerwin]

Tested that this is working with mssql against Azure Sql Server.

Notes:

• validates JSON if parameter value is a string
• encodes as JSON if parameter value is an object
• passes 'null' to the server if parameter value is null
• The inclusion of this new data type does not create any breaking changes to the codebase

I used the following logic to deduce the implementation:

1. Referenced 0xF4 and PLP based on SqlClient
2. That no parameter collation bytes are sent because Microsoft is very clear that JSON collation is fixed to Latin1_General_100_BIN2_UTF8 to match JSON Spec
3. That the protocol only needed 0xf4 id prefix and no length bytes since its a newer data type which doesn't have a legacy <= 8000 implementation like varchar did (and the 'json' type has no length setting in SQL)
4. That due to the fixed collation that UTF-8 encoding in validate() is sufficient

I did not use the iconv-lite library b/c it seemed like unnecessary overhead vs the direct Buffer.from( ) support in Node.

This resolves this Feature Request I created earlier before deciding to address with a PR after a little digging.

[matthewerwin]

@arthurschreiber @dhensby -- is there a plan to roll any updates out to Tedious in the near future? Noticed there has been no movement on the repo in 6+ months.

I had a couple in-flight items including this PR and would like to do what I can to help if needed. Another one was

tediousjs/node-mssql#1727

and it seems a deprecation on Microsoft's side related to that as well:
#1684

Generally it seems some maintenance things are accumulating without any regular interval releases from the Tedious team. Happy to help organize and move some things through for a release including reviewing other PR's if it's a matter of limited time to organize/test/review.

[arthurschreiber]

👋🏻 Heya! You're right, I didn't have a lot of time to spend on tedious recently.

If you don't mind, can you mention me on whatever issues are the most urgent in your eyes, and I'll promise to carve out some time to get them reviewed and merged. 🙇

[matthewerwin]

@arthurschreiber you bet -- I'll make a pass through the open PR's & tickets over the next week and see what stands out.

[Copilot]

Pull Request Overview

Adds support for a JSON data type by implementing its PLP encoding and registering it in the type registry.

• Introduce src/data-types/json.ts to handle JSON validation, length resolution, and PLP data streaming.
• Register the new Json type in src/data-type.ts, update the type lookup tables, and augment the documentation.

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
src/data-types/json.ts	New module defining the JSON type’s declaration, validation, and PLP encoding.
src/data-type.ts	Imports and registers Json in TYPE/TYPES and updates the docs table.

[Copilot]

Using instanceof String is uncommon and only matches String objects, not primitives. You can simplify to typeof parameter.value === 'string' to cover all string inputs.

Suggested change

	if ((parameter.value instanceof String || typeof (parameter.value) == 'string'))
	if (typeof parameter.value === 'string')

[Copilot]

Using .length on a string gives UTF-16 code-unit count, not the byte length for UTF-8. Switch to Buffer.byteLength(value, 'utf8') to get the correct byte length.

Suggested change

	return parameter.value.length;
	else return JSON.stringify(parameter.value).length;
	return Buffer.byteLength(parameter.value, 'utf8');
	else return Buffer.byteLength(JSON.stringify(parameter.value), 'utf8');

[Copilot]

Similar to above, prefer typeof value === 'string' instead of instanceof String to reliably detect primitive strings.

Suggested change

	if (!(value instanceof String || typeof (value) == 'string'))
	if (typeof value !== 'string')