skip duplicate DynamicRouteVar

[adhami3310]

No description provided.

[codspeed-hq]

Merging this PR will not alter performance

✅ 8 untouched benchmarks

---

_{Comparing skip-duplicate-DynamicRouteVar (eea992a) with main (7ee3026)}

[greptile-apps]

Greptile Summary

This PR adds a duplicate-registration guard to BaseState.setup_dynamic_args in reflex/state.py. When multiple routes share the same dynamic parameter name (e.g., [id] appearing in both /users/[id] and /posts/[id]), setup_dynamic_args was previously called once per route, causing the same DynamicRouteVar to be redundantly re-registered. The fix filters out any incoming arg that already exists as a DynamicRouteVar in cls.computed_vars before proceeding, short-circuiting entirely if all args are already registered.

Key changes:

• A dict comprehension at the top of setup_dynamic_args skips args whose key is already present in cls.computed_vars as a DynamicRouteVar.
• The existing if not args: return early-exit now also handles the case where all args were duplicates.
• No changes to tests were included with this fix.

Minor concern:

• The filter silently accepts the first registration of a given arg name, meaning if the same parameter name is used with a different type (SINGLE vs LIST) in a second route, the mismatch goes undetected at runtime. A warning log in that scenario would improve debuggability.

Confidence Score: 4/5

• This PR is safe to merge; the fix correctly prevents duplicate DynamicRouteVar registrations with one minor edge-case caveat.
• The change is small, focused, and correct for its stated purpose. The filter logic properly identifies already-registered DynamicRouteVars and skips them. The only concern is a silent type-mismatch if the same arg name is reused with different types (SINGLE vs LIST) across routes — an unlikely edge case that was already poorly handled before this PR. No regression in the common case is expected.
• reflex/state.py — specifically the new filter block at lines 1298–1306 and its interaction with the type (SINGLE/LIST) of existing DynamicRouteVar registrations.

Important Files Changed

Filename	Overview
reflex/state.py	Adds a pre-filter in setup_dynamic_args to skip args already registered as DynamicRouteVar, preventing duplicate registration when multiple routes share the same dynamic param name. Logic is correct for the common case; minor concern around silent type-mismatch when the same arg name is used with different types (SINGLE vs LIST) across different routes.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A["setup_dynamic_args(args)"] --> B["Filter: remove args already\nregistered as DynamicRouteVar"]
    B --> C{args empty\nafter filter?}
    C -- Yes --> D["return (no-op)"]
    C -- No --> E["_check_overwritten_dynamic_args(args)"]
    E --> F["For each remaining arg"]
    F --> G{arg type?}
    G -- SINGLE --> H["argsingle_factory(param)\n→ returns str from router.params"]
    G -- LIST --> I["arglist_factory(param)\n→ returns list[str] from router.params"]
    G -- other --> J["skip / continue"]
    H --> K["Create DynamicRouteVar"]
    I --> K
    K --> L["setattr(cls, param, dynamic_var)"]
    L --> M["Update cls.computed_vars,\ncls.vars, inherited vars"]

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[greptile-apps]

Silent type mismatch when same arg registered with different types

The filter skips any arg already registered as a DynamicRouteVar, regardless of the arg's type (SINGLE vs LIST). If two routes reuse the same parameter name but with different types — e.g., /users/[id] (SINGLE) and /posts/[...id] (LIST) — the first registration always wins silently, causing the wrong accessor (string vs. list) to be used for the second route.

Consider logging a warning when the incoming v (arg type) doesn't match the type that was used when the existing DynamicRouteVar was created, so developers are alerted to the mismatch rather than experiencing subtle runtime bugs:

# Skip dynamic args that have already been registered by a previous route.
args_to_skip = {}
new_args = {}
for k, v in args.items():
    existing = cls.computed_vars.get(k)
    if existing is not None and isinstance(existing, DynamicRouteVar):
        args_to_skip[k] = v
    else:
        new_args[k] = v

if args_to_skip:
    console.warn(
        f"Dynamic route args {list(args_to_skip)} are already registered and will be skipped."
    )
args = new_args

This is a low-likelihood edge case (same arg name with different types), but the silent failure mode is worth guarding against.