62 lines
2.2 KiB
ReStructuredText
62 lines
2.2 KiB
ReStructuredText
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.. _access_app_state:
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################
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Access App State
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################
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**Audience:** Users who want to know how the app state can be accessed.
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**Level:** Basic
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***********************
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What is the App State ?
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***********************
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In Lightning, each component is stateful and their state are composed of all attributes defined within their **__init__** method.
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The **App State** is the collection of all the components state forming the application.
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*****************************************
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What is the special about the App State ?
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*****************************************
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The **App State** is always up-to-date, even running an application in the cloud on multiple machines.
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This means that every time an attribute is modified in a work, that information is automatically broadcasted to the flow.
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With this mechanism, any component can **react** to any other component **state changes** through the flow and complex system can be easily implemented.
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Lightning requires a state based driven mindset when implementing the flow.
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************************************
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When do I need to access the state ?
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************************************
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As a user, you are interacting with your component attributes, so most likely,
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you won't need to access the component state directly, but it can be helpful to
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understand how the state works under the hood.
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For example, here we define a **Flow** component and **Work** component, where the work increments a counter indefinitely and the flow prints its state which contains the work.
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You can easily check the state of your entire app as follows:
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.. literalinclude:: ../code_samples/quickstart/app_01.py
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Run the app with:
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.. code-block:: bash
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lightning run app docs/quickstart/app_01.py
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And here's the output you get when running the above application using **Lightning CLI**:
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.. code-block:: console
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INFO: Your app has started. View it in your browser: http://127.0.0.1:7501/view
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State: {'works': {'w': {'vars': {'counter': 1}}}}
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State: {'works': {'w': {'vars': {'counter': 2}}}}
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State: {'works': {'w': {'vars': {'counter': 3}}}}
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State: {'works': {'w': {'vars': {'counter': 3}}}}
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State: {'works': {'w': {'vars': {'counter': 4}}}}
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...
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