reflex-dev/reflex reflex-base-v0.10.0

reflex-base@0.10.0

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Breaking Changes

• Require Python 3.11 or newer; Python 3.10 is no longer supported. (#7449)
• Assigning over a state var's field through its state class raises TypeError; change its default with the field's set_default instead, such as State.__fields__["count"].set_default(10). (#7516)
• Mutable values provided as state var defaults are deep-copied when assigned at class creation time or passed to set_default, so later changes to the original object no longer reach new sessions. A module-level list filled in after the class statement, such as options: list[str] = OPTIONS followed by OPTIONS.append(...), now starts every session empty: fill it before the class is defined, or declare default_factory=lambda: list(OPTIONS). (#7519)
• Formatting a backend var as a string, e.g. width=f"{State._size}px", now raises BackendVarFormatError (a VarTypeError) instead of embedding its default value. The error names the fix: read its default with State._size.default_value(), declare a constant shared by all sessions as ClassVar[...], or use a regular state var for a value the UI shows and updates. (#7456, #7496)
• reflex_base.utils.types.is_backend_base_variable and RESERVED_BACKEND_VAR_NAMES are removed: whether a state var is a backend var is now a property of its Field in get_fields(). By convention, fields named with a leading _ are backend vars. is_mutable_type moved to reflex_base.utils.types (still importable from reflex.istate.proxy). (#7312)
• PageContext.get() and CompileContext.get() now raise LookupError instead of RuntimeError when no context is active, the same as every other BaseContext subclass. Compiler plugins that catch RuntimeError around these calls should catch LookupError. (#6553)
• Remove reflex_base.constants.CustomComponents, which only the removed reflex component CLI used. (#6425)

Features

State vars

• Field is now the descriptor holding a state var's value, and EventHandler binds to the state that declares it when accessed on a state instance. (#7312)
• Add Field.set_default to change a state var's default, given exactly one of default or default_factory, such as State.__fields__["items"].set_default(["a"]). (#7519)
• A double-underscore state attribute (a name-mangled __private name or a dunder) can now be a backend var by declaring it with an explicit rx.field() value, e.g. __counter: rx.Field[int] = rx.field(0). Without one it stays a plain class attribute, like in 0.9.x. (#7465)

Configuration

• SQLALCHEMY_POOL_TIMEOUT, REFLEX_BACKEND_COLD_START_TIMEOUT, REFLEX_SOCKET_INTERVAL and REFLEX_SOCKET_TIMEOUT are timedelta settings, so they accept a unit suffix such as REFLEX_SOCKET_TIMEOUT=2m. A bare number is still read as seconds, so existing values keep their meaning. (#7138)
• REFLEX_AUTO_RELOAD_COOLDOWN, REFLEX_OPLOCK_HOLD_TIME and REFLEX_STATE_MANAGER_DISK_DEBOUNCE replace REFLEX_AUTO_RELOAD_COOLDOWN_TIME_MS, REFLEX_OPLOCK_HOLD_TIME_MS and REFLEX_STATE_MANAGER_DISK_DEBOUNCE_SECONDS, and take a duration such as 250ms or 5m. The old names still work and keep counting the unit in their name, with a deprecation warning; they are removed in 1.0. (#7138)
• Add the REFLEX_REDIS_MAX_CONNECTIONS and REFLEX_REDIS_POOL_TIMEOUT environment variables for bounding each asynchronous Redis client's connection pool. A configured cap must be at least 3 to leave room for the token manager's two pub/sub listeners and ordinary commands; the pool wait defaults to 2 seconds and must be above 0 and shorter than the state-lock lifetime. (#7179)

Other

• Add Var.deep_equals() for structural comparison of nested frontend values. (#7208)
• Add reflex_base.utils.log.supervise_output(), which runs a command with its stdout and stderr on pipes and writes every line it and its descendants print as a JSON record; lines that already are JSON log records pass through unchanged. Output that a descendant writes after the command exits is forwarded for at most a few seconds. (#7350)

Bug Fixes

Vars and compilation

• Negative-step slices of array and string Vars now match Python at a -1 bound (e.g. State.items[-1::-1] no longer renders an empty list), and a Var step (e.g. State.items[::State.step]) no longer raises RecursionError. (#7326)
• Var._replace(_var_data=...) no longer raises TypeError: dataclasses.replace() got multiple values for keyword argument '_var_data'. (#7256)
• A state that mixes in abc.ABC or another ABCMeta class (class MyMixin(ABC, rx.State, mixin=True)) no longer fails with a StateValueError claiming _abc_impl is reserved by BaseState. (#7339)
• Calling an event handler of up to four arguments on the state class with its arguments, plain or as Vars, and passing such a handler where a callable of its arguments is expected now type-check under ty, as they already did under pyright. Calls of handlers with five or more arguments can still be misreported by ty. (#7414)
• Auto-memoized @rx.memo wrapper names no longer repeat the wrapped memo component's tag. (#7004)
• Pages in apps with many substates no longer intermittently fail to server-render with a 500 such as SyntaxError: Invalid regular expression: /[^a-z-]/: Stack overflow. (#7369)
• Form submissions retain ID-backed controls with unset values while omitting IDs from non-controls. (#7227)

Events and uploads

• Flatten nested client event lists before dispatch and keep processing queued events after one event fails. (#7319)
• Events sent while a buffered upload is in flight are no longer chained to it: an uploading client that disconnects no longer cancels other clients' events, the upload's response no longer waits for them, and navigating during an upload cancels the previous page's unfinished on_load handlers again. Concurrent buffered uploads no longer hang or end each other's responses early, and state changes made after an upload's response has ended, such as by events a backend exception handler chains after the upload handler fails, now reach the client instead of being silently dropped. (#7357)
• sync=True rx.LocalStorage vars no longer bounce between open tabs forever when the value changes while other tabs are loading, or in several tabs at once: a tab no longer writes a value it sent to the backend back over a newer one another tab stored meanwhile. (#7505)
• rx.download(data=State.var) percent-encodes the JSON it puts in the data: URL, so a # or % in the data no longer truncates or corrupts the downloaded file. (#7325)
• OpenTelemetry spans of top-level events enqueued during an HTTP request (a chunked upload, or a custom API route calling app.event_processor.enqueue) no longer carry a reflex.event.parent_txid naming the event processor's root context; only chained events name the event that produced them. (#7358)

Other

• Deprecation warnings no longer point at a pseudo-location such as <string> or <frozen importlib._bootstrap> when the deprecated call runs inside generated or frozen code; the location now names the first real user file. (#7138)

Performance

• Speed up first page loads by opening the websocket before React mounts and hydrating the page in the same round trip as the connect. (#7064)
• Lower the CPU cost of every backend event: cached computed var reads, field reads and writes, event dispatch and the JSON encoding of state deltas are faster. A computed var returning a value of the wrong type is now logged once per computed value instead of on every read, and EventHandler.is_background and EventHandler.supersedes are read once per handler, so mark the function before the handler is first used. (#7370)
• Building Vars (operations, comparisons, rx.cond, rx.foreach) is up to twice as fast, so pages that derive many Vars compile faster; the generated code is unchanged. (#7370)
• Reading a cached computed var no longer re-validates its return type, and in production mode state var assignments and computed var results check only the outer type instead of walking every element. The type checks only log errors, so this changes no behavior beyond fewer element-level log messages in production. (#7353)
• Reduce event-queue overhead when prepending events and processing events with a connected socket. (#7053)
• Compile memoized components faster by reusing unchanged memo bodies instead of rendering them again. (#7123)

Miscellaneous

• Update generated apps to React 19.3, Vite 8.3.2, Socket.IO client 4.8.4, Autoprefixer 10.6.1, and PostCSS 8.5.29. Update the bundled Bun runtime to 1.4.2. (#7424)