fix(postgrest): use POST for rpc() with get:true and object args

[PedroHenrique0713]

🔍 Description

What changed?

rpc() has a guard (_hasObjectArg) that falls back to POST + JSON body when an argument is an object or array-of-objects, because objects cannot be serialized into URL query params. This guard previously only checked head — it now checks head || get.

The Prefer: return=minimal header is now only set when head is true (a get: true call wants the response data back, so it must not request a minimal response).

Why was this change needed?

A call like:

await supabase.rpc("fn", { data: { key: "value" } }, { get: true })

fell into the GET branch because _hasObjectArg was head && ... (false when head is false). The object was then serialized into the URL as [object Object] — silently corrupting the request. PostgREST would receive ?data=[object Object] instead of the intended JSON body.

The head: true path was already correct (it triggered the POST fallback and set return=minimal). This PR extends the same behavior to get: true, minus the return=minimal header (since get wants the response payload).

📸 Screenshots/Examples

// Before: GET /rpc/fn?data=[object Object]  — silently broken
// After:  POST /rpc/fn  body={"data":{"key":"value"}}  — correct
await supabase.rpc("fn", { data: { key: "value" } }, { get: true })

🔄 Breaking changes

• This PR contains no breaking changes

Calls with primitive args (strings, numbers, arrays of primitives) are unaffected — they still use GET with URL params as before.

📋 Checklist

• I have read the Contributing Guidelines
• My PR title follows the conventional commit format: fix(postgrest): ...
• I have run pnpm nx format to ensure consistent code formatting
• I have added tests for new functionality (if applicable)
• I have updated documentation (if applicable)

📝 Additional notes

Validated E2E: 3/3 tests pass. The first two tests inspect the wire (method/body/headers) via a mock fetch since the test DB has no function that accepts a jsonb arg; the third test hits the real PostgREST server to confirm the primitive-arg get: true path is unchanged.

Local checks: jest test/rpc-get-object-args.test.ts → 3 passed, tsc --noEmit → clean, prettier --check → clean.

[coderabbitai]

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📥 Commits

Reviewing files that changed from the base of the PR and between 5c18b62 and 5d0054b.

📒 Files selected for processing (2)

• packages/core/postgrest-js/src/PostgrestClient.ts
• packages/core/postgrest-js/test/rpc-get-object-args.test.ts

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📝 Walkthrough

Summary by CodeRabbit

• Bug Fixes
  • Improved RPC requests with object arguments when using GET options.
  • Prevented object values from being incorrectly serialized into request URLs.
  • Preserved minimal-response behavior for HEAD requests.
  • Confirmed that RPC requests with primitive arguments continue using GET as expected.

Walkthrough

PostgrestClient.rpc now sends object-valued arguments using POST when get: true or head: true is specified. return=minimal is applied only to object-argument requests using head: true, while count preferences remain available for other requests. New tests verify POST bodies, header behavior, and the existing GET path for primitive arguments.

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