Decode single values in ArrayQuery

[zoriya]

If we have a t.Transform(t.Array()) in a query param and only pass one value, the value is never Decoded.

minimal repro:

import { Elysia, t } from "elysia";

new Elysia()
	.get(
		"/",
		({ query }) => {
			return query;
		},
		{
			query: t.Object({
				a: t
					.Transform(t.Array(t.String()))
					.Decode((x) => {
						return { decoded: x };
					})
					.Encode((x) => {
						throw new Error("nop");
					}),
				b: t.Optional(
					t
						.Transform(t.String())
						.Decode((x) => {
							return { decoded: x };
						})
						.Encode((x) => {
							throw new Error("nop");
						}),
				),
			}),
		},
	)
   .listen(3000);

doing curl http://localhost:3000?a=toto,tata we get the expected decoded value:

{
  "a": {
    "decoded": [
      "toto",
      "taat"
    ]
  }
}

doing it with a single value also works curl http://localhost:3000?a=toto

{
  "a": {
    "decoded": [
      "toto"
    ]
  }
}

but adding another transformed query params break it for a single value: curl http://localhost:3000?a=toto&b=toto

{
  "a": [
    "toto"
  ],
  "b": {
    "decoded": "toto"
  }
}

while adding a second value works: curl http://localhost:3000?a=toto,tata&b=toto

{
  "a": {
    "decoded": [
      "toto",
      "tata"
    ]
  },
  "b": {
    "decoded": "toto"
  }
}

After this patch is applied, this works too! curl 'http://localhost:8901?a=toto&b=toto'

{
  "a": {
    "decoded": [
      "toto"
    ]
  },
  "b": {
    "decoded": "toto"
  }
}

Summary by CodeRabbit

• Bug Fixes
  • Improved consistency in array query decoding for single-value string inputs. String values are now processed through the same validation pipeline as comma-separated values, ensuring uniform handling across all input types.

_{✏️ Tip: You can customize this high-level summary in your review settings.}

[coderabbitai]

Walkthrough

ArrayQuery.Decode now routes single-element string inputs through compiler.Decode by passing [value], instead of returning the raw [value], making decoding consistent with comma-separated inputs.

Changes

Cohort / File(s)	Change Summary
Array Validation Consistency src/type-system/index.ts	ArrayQuery.Decode changed to call compiler.Decode([value]) for single-element string inputs rather than returning the raw [value], aligning single-value decoding with comma-separated decoding logic.

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~3 minutes

Poem

🐰 One string, one path, now validated true,
No raw escapes when decoding is due,
Through compiler's eye, both single and bunch,
Consistency hopped—a satisfying crunch! 🥕

Pre-merge checks and finishing touches

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'Decode single values in ArrayQuery' directly and accurately describes the main change: applying compiler-based decoding to single-element string inputs in ArrayQuery, which fixes the reported bug where single values weren't decoded correctly.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

✨ Finishing touches

• 📝 Generate docstrings

---

📜 Recent review details

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between e16dc82 and abf62bd.

📒 Files selected for processing (1)

• src/type-system/index.ts

🚧 Files skipped from review as they are similar to previous changes (1)

• src/type-system/index.ts

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[pkg-pr-new]

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npm i https://pkg.pr.new/elysiajs/elysia@1655

commit: abf62bd