st.experimental_user

st.experimental_user is a Streamlit command that returns information about the logged-in user on Streamlit Cloud. It allows developers to personalize apps for the user viewing the app. In a private Streamlit Cloud app, it returns a dictionary with the viewer's email. This value of this field is empty in a public Streamlit Cloud app to prevent leaking user emails to developers.

The API closely resembles that of st.session_state and st.secrets. It follows a field-based API, which is very similar to Python dictionaries.

Allowed fields

The st.experimental_user command returns a dictionary with only one field: email.

Display the allowed field by passing the command to st.write:

# Display the contents of the dictionary
st.write(st.experimental_user)

The above displays a dict with one field and value. The field is always email:

{
  "email": "value"
}

You can check if a field exists in st.experimental_user:

# Returns True if the field exists
"email" in st.experimental_user

# Returns False if the field does not exist
"name" in st.experimental_user

Read values

Read the value of the email field and display it by passing to st.write:

# Dictionary like API
st.write(st.experimental_user['email'])

# Attribute API
st.write(st.experimental_user.email)

The above outputs either None or the logged-in user's email or test@localhost.com, depending on where the app is running. Read further to learn about st.experimental_user's context-dependent behavior.

Updates and modifications

Keys and values for st.experimental_user cannot be updated or modified. Streamlit throws a handy StreamlitAPIException exception if you try to update them:

st.experimental_user.name = None
# Throws an exception!

st.experimental_user.email = "hello"
# Throws an exception!

Context-dependent behavior

The value of st.experimental_user.email is context-dependent. It returns a value depending on where the app is running. The private or public app can be running on Streamlit Cloud, locally, or on a 3rd party cloud provider. Let's look at the different scenarios.

Private app on Streamlit Cloud

Users need to be logged in to Streamlit Cloud to view private apps. If a user is not logged, they see:

If a user is logged in, st.experimental_user.email returns the user's email. Suppose a user logged in to Streamlit Cloud using jane@email.com:

st.experimental_user.email
# Returns: jane@email.com

Public app on Streamlit Cloud

Currently, st.experimental_user.email returns information about the logged-in user of private apps on Streamlit Cloud. If used in a public app, it returns None. For example:

st.experimental_user.email
# Returns: None

This value of this field is empty in a public Streamlit Cloud app to prevent leaking user emails to developers.

Local development

When developing locally, st.experimental_user.email returns test@localhost.com. We don't return None to make it easier to locally test this functionality. For example:

st.experimental_user.email
# Returns: test@localhost.com

App deployed on a 3rd party cloud provider

When deploying an app on a 3rd party cloud provider (e.g. Amazon EC2, Heroku, etc), st.experimental_user.email behaves the same as during local development. For example:

st.experimental_user.email # On a 3rd party cloud provider
# Returns: test@localhost.com

Examples

The ability to personalize apps for the user viewing the app is a great way to make your app more engaging.

It unlocks a plethora of use-cases for developers, some of which could include: showing additional controls for admins, visualizing a user's Streamlit history, a personalized stock ticker, a chatbot app, and much more. We're excited to see what you build with this feature!

Here's a code snippet that shows extra buttons for admins:

# Show extra buttons for admin users.
ADMIN_USERS = {
    'person1@email.com',
    'person2@email.com',
    'person3@email.com'
}
if st.experimental_user.email in ADMIN_USERS:
    display_the_extra_admin_buttons()
display_the_interface_everyone_sees()

Show different content to users based on their email address:

# Show different content based on the user's email address.
if st.experimental_user.email == 'jane@email.com':
    display_jane_content()
elif st.experimental_user.email == 'adam@foocorp.io':
    display_adam_content()
else:
    st.write("Please contact us to get access!")

Greet users with their name that's stored in a database:

# Greet the user by their name.
if st.experimental_user.email:
    # Get the user's name from the database.
    name = get_name_from_db(st.experimental_user.email)
    st.write('Hello, %s!' % name)

Caveats and limitations

• st.experimental_user is read-only. You cannot update or modify its value. Doing so will throw a StreamlitAPIException.
• A valid email is returned only if the user is logged in to Streamlit Cloud and the app is private. Else, None or test@localhost.com is returned.
• This is an experimental feature. Experimental features and their APIs may change or be removed at any time. To learn more, click here.