gramlot.

Course · Lesson 08 of 20

Name behavior and understand lifecycle

Follow a named Logic method from its Python declaration to its browser implementation.

Reading · Practice2 sectionsPrerequisites: Run an action at the right time
Course contents
Orientation
  1. 01 Install Gramlot and create Hello world
  2. 02 Connect text and colour to Data
  3. 03 Explore Data and Source with the inspector
  4. 04 Use relative and symbolic paths, then dataFormula
  5. 05 Call the server with dataRpc and .remote
Start a project
  1. 01 Create your first project
  2. 02 Read and compose Source
  3. 03 Initialize structured Data
  4. 04 Connect fields and values
Build a form
  1. 05 Accept values, preserve drafts
  2. 06 Declare a calculation
  3. 07 Run an action at the right time
  4. 08 Name behavior and understand lifecycle
Compose an interface
  1. 09 Arrange an application with containers
  2. 10 Style the page you own
  3. 11 Publish messages and ask before acting
  4. 12 Format values without changing Data
Connect services
  1. 13 Call an endpoint
  2. 14 Load a Source fragment
  3. 15 Load Data when it is read
  4. 16 Save, restore and send Data deliberately
Deliver your work
  1. 17 Organize pages and choose a host
  2. 18 Read the JavaScript edition
  3. 19 Deliver the JavaScript edition offline
  4. 20 Explain and change a complete form

Read both files

The project generated in lesson 01 already uses named Logic. A formula names a method with func; that method returns the calculated value. A Logic module exports class Logic. The Python Page remains the place where inputs and their bindings are declared.

Read the Named logic gallery example with its Python and Logic tabs. Follow one parameter into the method and the return value back to the formula’s result path. A reusable function does not need a second binding language.

Initialize at the appropriate stage

Data declarations are installed before the first DOM build. _init is for initialization before rendering; _onBuilt follows the first successful build; _onStart runs when the page is ready. Use the stage that matches the work.

A method that needs a rendered element cannot assume that element exists during _init. Removing a declaration also releases its owned subscriptions and timers. Save code changes in the authored files and reload through the normal host lifecycle.

Your turn

Try it yourself

  1. In your generated hello project, locate the func name in Python and the corresponding method in pages/index.js.
  2. Change only a literal part of the greeting returned by that method. Save, restart and reload.
  3. Open Lifecycle and compare the reported order with your prediction.

Check your understanding

Does using a named method move the calculation onto the Python server?

Show the answer and expected result

No. Named Logic still runs in the browser. It separates browser code from the declarations, supports reuse and works with the generated strict CSP profile. A server calculation is an endpoint, introduced later.

Working examples and reference