fix(triggers): support POST with query params for autoscan compatibility

[jkristoph]

Summary

• Fixes autoscan-to-autoscan forwarding compatibility
• The original autoscan sends scan requests between instances as POST /triggers/manual?dir=/path with an empty body (see targets/autoscan/api.go)
• The current POST handler requires a JSON body and rejects Manual/Autoscan trigger types, making it incompatible
• This was previously documented in feat: Autoscan Legacy Trigger #307, which included an nginx workaround

Changes

• Modified trigger_post to accept raw Bytes instead of Json<Value>, allowing empty bodies
• When the body is empty or not valid JSON, the handler falls back to query parameter parsing (same logic as the GET handler)
• Extracted shared query-param handling into trigger_get_inner() to avoid code duplication
• Existing JSON-body triggers (Sonarr, Radarr, etc.) continue to work unchanged

How autoscan sends requests

From targets/autoscan/api.go in the autoscan repo:

req, err := http.NewRequestWithContext(ctx, http.MethodPost, triggerURL, http.NoBody)
q := url.Values{}
q.Add("dir", folder)
req.URL.RawQuery = q.Encode()

Test plan

• POST /triggers/<autoscan-type>?dir=/path with no body → should succeed (was failing)
• POST /triggers/<manual-type>?path=/file with no body → should succeed (was failing)
• GET /triggers/<autoscan-type>?dir=/path → should still work (unchanged)
• GET /triggers/<manual-type>?path=/file → should still work (unchanged)
• POST /triggers/sonarr with JSON body → should still work (unchanged)
• HEAD /triggers/manual health check → should still work (unchanged)

🤖 Generated with Claude Code

[dan-online]

Nice direction here. I think the cleanest fix is to parse the query string based on trigger_settings instead of going through the untagged enum first. That lets manual normalize the legacy dir shape explicitly, and it keeps invalid non-empty JSON failing fast instead of silently falling back.

Something like:

Suggested change

	let parsed_body: Option<serde_json::Value> = if body.is_empty() {
	None
	} else {
	serde_json::from_slice(&body).ok()
	};
	let has_body = parsed_body
	.as_ref()
	.map(|b| !b.is_null())
	.unwrap_or(false);
	if !has_body {
	if let Ok(query) =
	Query::<TriggerQueryParams>::from_query(req.query_string())
	{
	return trigger_get_inner(&trigger, query.into_inner(), &manager, trigger_settings)
	.await;
	}
	let query_fallback = if body.is_empty() {
	match trigger_settings {
	Trigger::Manual(_) | Trigger::Bazarr(_) => Query::<ManualQueryParams>::from_query(req.query_string())
	.map(|q| TriggerQueryParams::Manual(q.into_inner()))
	.or_else(|_| {
	Query::<AutoscanQueryParams>::from_query(req.query_string()).map(|q| {
	TriggerQueryParams::Manual(ManualQueryParams {
	path: q.into_inner().dir,
	hash: None,
	})
	})
	})
	.ok(),
	Trigger::Autoscan(_) => Query::<AutoscanQueryParams>::from_query(req.query_string())
	.map(|q| TriggerQueryParams::Autoscan(q.into_inner()))
	.ok(),
	_ => None,
	}
	} else {
	None
	};
	if let Some(query) = query_fallback {
	return trigger_get_inner(&trigger, query, &manager, trigger_settings).await;
	}
	let parsed_body: Option<serde_json::Value> = if body.is_empty() {
	None
	} else {
	Some(
	serde_json::from_slice(&body)
	.map_err(|_| actix_web::error::ErrorBadRequest("Invalid JSON body"))?,
	)
	};

[dan-online]

Not implemented feels a little odd here. I think 400 Invalid request would be a safer response for unsupported combinations.

Something like:

Suggested change

	_ => Ok(HttpResponse::BadRequest().body("Invalid request")),