Form
# Low Level Form is Experimental Please use the High Level Form for now for production.
Forms are used to collect information from your users. Forms group the inputs and submit them together.
Basic Example
Here is an example of a form collecting an email address, with built-in validation on the email. If email entered is invalid, the form cannot be submitted. Note that the form.submit button is not automatically disabled. It is still clickable, but does not submit the form data. After successful submission, an alert window shows up and the form is cleared. There are a few flex containers used in the example to control the layout of the form components.
rx.form.root(
rx.form.field(
rx.flex(
rx.form.label("Email"),
rx.form.control(
rx.input(
placeholder="Email Address",
# type attribute is required for "typeMismatch" validation
type="email",
),
as_child=True,
),
rx.form.message(
"Please enter a valid email",
match="typeMismatch",
),
rx.form.submit(
rx.button("Submit"),
as_child=True,
),
direction="column",
spacing="2",
align="stretch",
),
name="email",
),
on_submit=lambda form_data: rx.window_alert(
form_data.to_string()
),
reset_on_submit=True,
)In this example, the rx.input has an attribute type="email" and the form.message has the attribute match="typeMismatch". Those are required for the form to validate the input by its type. The prop as_child="True" is required when using other components to construct a Form component. This example has used rx.input to construct the Form Control and button the Form Submit.
Form Anatomy
form.root(
form.field(
form.label(...),
form.control(...),
form.message(...),
),
form.submit(...),
)A Form Root (form.root) contains all the parts of a form. The Form Field (form.field), Form Submit (form.submit), etc should all be inside a Form Root. A Form Field can contain a Form Label (form.label), a Form Control (form.control), and a Form Message (form.message). A Form Label is a label element. A Form Control is where the user enters the input or makes selections. By default, the Form Control is a input. Using other form components to construct the Form Control is supported. To do that, set the prop as_child=True on the Form Control.
The Form Message is a validation message which is automatically wired (functionality and accessibility). When the Form Control determines the input is invalid, the Form Message is shown. The match prop is to enable client side validation. To perform server side validation, both the force_match prop of the Form Control and the server_invalid prop of the Form Field are set together.
The Form Submit is by default a button that submits the form. To use another button component as a Form Submit, include that button as a child inside form.submit and set the prop as_child=True.
The on_submit prop of the Form Root accepts an event handler. It is called with the submitted form data dictionary. To clear the form after submission, set the reset_on_submit=True prop.
Data Submission
As previously mentioned, the various pieces of data in the form are submitted together as a dictionary. The form control or the input components must have the name attribute. This name is the key to get the value from the form data dictionary. If no validation is needed, the form type components such as Checkbox, Radio Groups, TextArea can be included directly under the Form Root instead of inside a Form Control.
Results
import reflex as rx
import reflex.components.radix.primitives as rdxp
class RadixFormSubmissionState(rx.State):
form_data: dict
def handle_submit(self, form_data: dict):
"""Handle the form submit."""
self.form_data = form_data
@rx.var
def form_data_keys(self) -> list:
return list(self.form_data.keys())
@rx.var
def form_data_values(self) -> list:
return list(self.form_data.values())
def radix_form_submission_example():
return rx.flex(
rx.form.root(
rx.flex(
rx.flex(
rx.checkbox(
default_checked=True,
name="box1",
),
rx.text("box1 checkbox"),
direction="row",
spacing="2",
align="center",
),
rx.radio.root(
rx.flex(
rx.radio.item(value="1"),
"1",
direction="row",
align="center",
spacing="2",
),
rx.flex(
rx.radio.item(value="2"),
"2",
direction="row",
align="center",
spacing="2",
),
rx.flex(
rx.radio.item(value="3"),
"3",
direction="row",
align="center",
spacing="2",
),
default_value="1",
name="box2",
),
rx.input(
placeholder="box3 textfield input",
name="box3",
),
rx.select.root(
rx.select.trigger(
placeholder="box4 select",
),
rx.select.content(
rx.select.group(
rx.select.item(
"Orange", value="orange"
),
rx.select.item(
"Apple", value="apple"
),
),
),
name="box4",
),
rx.flex(
rx.switch(
default_checked=True,
name="box5",
),
"box5 switch",
spacing="2",
align="center",
direction="row",
),
rx.flex(
rx.slider(
default_value=[40],
width="100%",
name="box6",
),
"box6 slider",
direction="row",
spacing="2",
align="center",
),
rx.text_area(
placeholder="Enter for box7 textarea",
name="box7",
),
rx.form.submit(
rx.button("Submit"),
as_child=True,
),
direction="column",
spacing="4",
),
on_submit=RadixFormSubmissionState.handle_submit,
),
rx.divider(size="4"),
rx.text(
"Results",
weight="bold",
),
rx.foreach(
RadixFormSubmissionState.form_data_keys,
lambda key, idx: rx.text(
key,
" : ",
RadixFormSubmissionState.form_data_values[
idx
],
),
),
direction="column",
spacing="4",
)Validation
Server side validation is done through Computed Vars on the State. The Var should return a boolean flag indicating when input is invalid. Set that Var on both the server_invalid prop of form.field and the force_match prop of form.message. There is an example how to do that in the Final Example.
Final Example
The final example shows a form that collects username and email during sign-up and validates them using server side validation. When server side validation fails, messages are displayed in red to show what is not accepted in the form, and the submit button is disabled. After submission, the collected form data is displayed in texts below the form and the form is cleared.
Username submitted:
Email submitted:
import re
import reflex as rx
import reflex.components.radix.primitives as rdxp
class RadixFormState(rx.State):
# These track the user input real time for validation
user_entered_username: str
user_entered_email: str
# These are the submitted data
username: str
email: str
mock_username_db: list[str] = ["reflex", "admin"]
@rx.var
def invalid_email(self) -> bool:
return not re.match(
r"[^@]+@[^@]+\.[^@]+", self.user_entered_email
)
@rx.var
def username_empty(self) -> bool:
return not self.user_entered_username.strip()
@rx.var
def username_is_taken(self) -> bool:
return (
self.user_entered_username
in self.mock_username_db
)
@rx.var
def input_invalid(self) -> bool:
return (
self.invalid_email
or self.username_is_taken
or self.username_empty
)
def handle_submit(self, form_data: dict):
"""Handle the form submit."""
self.username = form_data.get("username")
self.email = form_data.get("email")
def radix_form_example():
return rx.flex(
rx.form.root(
rx.flex(
rx.form.field(
rx.flex(
rx.form.label("Username"),
rx.form.control(
rx.input(
placeholder="Username",
# workaround: `name` seems to be required when on_change is set
on_change=RadixFormState.set_user_entered_username,
name="username",
),
as_child=True,
),
# server side validation message can be displayed inside a rx.cond
rx.cond(
RadixFormState.username_empty,
rx.form.message(
"Username cannot be empty",
color="var(--red-11)",
),
),
# server side validation message can be displayed by `force_match` prop
rx.form.message(
"Username already taken",
# this is a workaround:
# `force_match` does not work without `match`
# This case does not want client side validation
# and intentionally not set `required` on the input
# so "valueMissing" is always false
match="valueMissing",
force_match=RadixFormState.username_is_taken,
color="var(--red-11)",
),
direction="column",
spacing="2",
align="stretch",
),
name="username",
server_invalid=RadixFormState.username_is_taken,
),
rx.form.field(
rx.flex(
rx.form.label("Email"),
rx.form.control(
rx.input(
placeholder="Email Address",
on_change=RadixFormState.set_user_entered_email,
name="email",
),
as_child=True,
),
rx.form.message(
"A valid Email is required",
match="valueMissing",
force_match=RadixFormState.invalid_email,
color="var(--red-11)",
),
direction="column",
spacing="2",
align="stretch",
),
name="email",
server_invalid=RadixFormState.invalid_email,
),
rx.form.submit(
rx.button(
"Submit",
disabled=RadixFormState.input_invalid,
),
as_child=True,
),
direction="column",
spacing="4",
width="25em",
),
on_submit=RadixFormState.handle_submit,
reset_on_submit=True,
),
rx.divider(size="4"),
rx.text(
"Username submitted: ",
rx.text(
RadixFormState.username,
weight="bold",
color="var(--accent-11)",
),
),
rx.text(
"Email submitted: ",
rx.text(
RadixFormState.email,
weight="bold",
color="var(--accent-11)",
),
),
direction="column",
spacing="4",
)