DOC-6968 Add the four SCAN steps to seven cmds_generic client examples

[andy-stark-redis]

DOC-6968 — the four SCAN steps for seven clients

Adds scan1–scan4 to hiredis, go-redis, jedis, lettuce-async, lettuce-reactive, ioredis and predis in the cmds_generic set. 27 implementations, 822 lines.

Omission warnings: 63 → 36. content/commands/scan.md is back to 12 client tabs on scan1, scan2 and scan4 (from 5), and 12 on scan3 where PHP is legitimately absent — see below.

@dwdougherty this is the "next PR" from #3811: the warnings that triggered your OCD are now down by 43%, and scan.md was the page paying the visible price.

18 is not the number of matching keys

*11* matches 19 of key:1…key:1000 — I counted them. The reference gets 18 because its COUNT 1000 call continues from the cursor left by four preceding default-COUNT iterations, one of which has already yielded a match. My first ioredis attempt restarted at cursor 0, got 19, and failed its own assertion, which is how this surfaced.

Every tab now mirrors the reference's continuation semantics. One nuance for the record: on Redis 8.8 the observed split is 0, 0, 0, 1, 18, whereas the page's CLI transcript shows the match landing on the first iteration. Same total, different distribution — the split depends on iteration order, which matters for the next point.

Why Go's scan2 prints less than its siblings

A Go Example function only runs under go test if it has an // Output: block, and that block must match stdout exactly. Encoding the per-iteration counts (0,0,0,1) would make the Go test fail whenever SCAN's iteration order shifted — a red build for a reason unrelated to the docs.

So Go runs the four iterations but prints only the final 18. Same headline number, less visible narrative, no new fragility. The alternative (match the siblings exactly, accept Go as the canary that breaks first) was considered and rejected.

predis cannot express scan3, so PHP is absent from it

SCAN.php::prepareOptions in predis 3.5.1 emits only MATCH and COUNT. TYPE is silently dropped — probed against a live server:

with TYPE=zset -> geokey, stringkey, zkey
without TYPE   -> geokey, stringkey, zkey

stringkey is a plain string. An idiomatic-looking $r->scan(0, ['TYPE' => 'zset']) returns everything, which is worse than an absent tab, and using executeRaw in a docs example teaches the wrong thing. PHP therefore has scan1, scan2 and scan4 only.

This is the first real use of the behaviour added in #3811: PHP's absence renders as a cleanly omitted tab rather than a 46-line whole-file dump, and the one remaining warning for cmds_generic/scan3 is a truthful record rather than noise.

Verification

All seven PASS against Redis 8.8.0 via build/example-test-harness/run.sh cmds_generic, including hiredis through the portable C runner added earlier in this ticket. Observed output was checked against every >>> comment.

Two pre-existing failures in that sweep are not from this change — verified by re-running both with these changes stashed:

Client	Failure	Cause
nredisstack	CS0246: SkipIfRedisFactAttribute could not be found	the portable C# stub lacks that attribute
rust-async	unresolved import futures_util, AsyncIter is not an iterator	async iteration API drift in the pinned redis-rs

Neither file is touched here. Both deserve their own tickets.

What's left

36 warnings: cmds_generic 18 (del/expire/ttl 5 each, exists 2, scan3 1 for PHP), cmds_hash 12 (C and ioredis), query_vector 4 (deliberately out of scope), cmds_stream 2.

🤖 Generated with Claude Code

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Note

Low Risk
Docs and example-test harness only; no production runtime or API changes.

Overview
Adds scan1–scan4 doc examples to seven cmds_generic clients (hiredis, go-redis, jedis, lettuce-async/reactive, ioredis, predis) so scan.md can show more client tabs and cut omission warnings.

scan1: set + SSCAN with MATCH. scan2: SCAN with MATCH *11*, four default-COUNT iterations then COUNT 1000 continuing from the prior cursor (final batch 18 keys). scan3: SCAN … TYPE zset over geo/zset keys. scan4: HSCAN vs NOVALUES.

predis gets scan1, scan2, and scan4 only—TYPE on SCAN is not supported idiomatically. go-redis scan2 still runs the loop but // Output: asserts only 18, not per-iteration counts.

^{Reviewed by Cursor Bugbot for commit 06bb0e5. Bugbot is set up for automated code reviews on this repo. Configure here.}

[github-actions]

DOC-6968

[github-actions]

🧠 Redis Memory

Found 5 related items from repository history (5 new this commit):

• Commit — DOC-6968 Add the missing incr step to nine cmds_string client examples 🆕

  DOC-6968 Add the missing incr step to nine cmds_string client examples

• PR — DOC-6968 Fix two node-redis step names, and add the missing incr step for nine clients 🆕

  DOC-6968 — two node-redis step names that never matched their sets

• PR — DOC-6887 Add hash field expiration examples to hash data type page 🆕

  What

• PR — DOC-6767 added Go scan/buffer API page 🆕

• PR — DOC-6968 Omit a clients-example tab when that client lacks the requested step 🆕

  DOC-6968 — omit a clients-example tab when the client lacks the requested step

Memory updated at 06bb0e5