Read Json File Python 2 to Dash Python

Dash 2.0 Migration

Dash 2.0 introduces several new features, including Long Callbacks, Flexible Callback Signatures, and a simpler import statement.

Some updates to Dash change how existing features piece of work, and you will need to update your apps for them to go on to part correctly.

Below is an outline of what updates y'all'll demand to make to your apps, along with a short overview of new functionality yous'll discover in Dash ii.0.

Breaking Changes — Callbacks

If you lot are currently naming arguments to @app.callback with country=, y'all demand to either too use input for the input arguments, or remove country.

Breaking Changes — Python two Support

Equally of version ii.0, Dash no longer supports Python two.

Recommended Updates — Import Statements

Dash 2.0 includes a simpler way to import Dash also equally its dependencies and components.

If you update your apps to utilize Dash ii.0, we recommend y'all use this simpler import statement and replace references to dash_html_components, dash_core_components, and dash_table in your app imports.

Dash 1.x

          import dash_html_components equally html import dash_core_components as dcc import dash_table                  

Dash two.0

          from dash import Dash, callback, html, dcc, dash_table, Input, Output, State, MATCH, ALL                  

In the above example, html, dcc, and dash_table are imported along with Nuance, callback, Input, Output, Land, MATCH, and ALL.

Installs

The changes that allow simpler import of dash_html_components, dash_core_components, and dash_table also affect installs of these components. If y'all have these referenced in whatsoever requirements.txt files, yous should update them.

New Features to Improve your Apps

As you lot update your apps, you may likewise desire to consider trying out some of Dash ii.0's new features.

Long Callbacks

If yous are currently using Dash 1.x and experiencing server timeouts with callbacks that run for a long time, y'all can use long callbacks to solve this event. Long callbacks run callback logic in a separate procedure, significant the app is withal available while the callback runs. Run into the Long Callbacks chapter for more details.

Flexible Callback Signatures

In Dash 1.x callback arguments are positional, significant arguments are passed to the callback function in the aforementioned order equally they are in the callback decorator. Flexible callbacks
allow for either positional or keyword arguments. Meet the Flexible Callback Signatures chapter for more details.

@dash.callback

The decorator @dash.callback is an alternative to using @app.callback in your apps. It is useful when building reusable components using pattern-matching callbacks and All-in-One components. To import and use it:

          import dash  @nuance.callback(...)                  

Similarly, @dash.clientside_callback can exist used equally an alternative to @app.clientside_callback:

          import dash  @dash.clientside_callback(...)                  

Both can also be imported past importing from dash like this:

          from dash import clientside_callback, callback                  

And then used like this:

          @callback(...)                  

          @clientside_callback(...)                  

Limitations

• The global level prevent_initial_callbacks via app = dash.Dash(__name__, prevent_initial_callbacks=True) is not supported. It defaults to False. This is however configurable on a per-callback level.
• @nuance.callback won't work in projects with multiple app declarations.
  (If y'all are using multiple app declarations to create a multi-page app, retrieve that this is not officially
  supported and consider changing to the recommended dcc.Location multi-page app solution).
• @nuance.long_callback is not nevertheless supported.

orjson Support

Dash ii.0 adds opt-in support for orjson. If the orjson library is installed, Dash volition utilise it to serialize data to JSON, improving callback performance. Encounter "Data Serialization" in the Functioning chapter for more information.

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Source: https://dash.plotly.com/dash-2-0-migration