refactor(variables): replace deprecated 'get_any' with 'get' method

[laipz8200]

Checklist:

Important

Please review the checklist below before submitting your pull request.

• Please open an issue before creating a PR or link to an existing issue
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I ran dev/reformat(backend) and cd web && npx lint-staged(frontend) to appease the lint gods

Description

• Removed deprecated get_any method in favor of the get method for variable retrieval across multiple nodes.
• Improved error handling for variable retrieval by adding checks for variable existence and type validation.
• Introduced specific error messages for missing or invalid variable types to enhance debugging capabilities.

Fixes

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update, included: Dify Document
• Improvement, including but not limited to code refactoring, performance optimization, and UI/UX improvement
• Dependency upgrade

Testing Instructions

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce. Please also list any relevant details for your test configuration

• Test A
• Test B

[bowenliang123]

LGTM. Long-awaited refactoring.

[ChristenJacquottet]

This refactoring is breaking many workflows because some users were reliant on the previous behavior where input variables could be null. The deprecated get_any method allowed workflows to proceed even with missing or null values, providing fault tolerance. The new get method is stricter and requires all variables to exist, resulting in unexpected failures for workflows that aren't explicitly handling missing inputs.

[laipz8200]

This refactoring is breaking many workflows because some users were reliant on the previous behavior where input variables could be null. The deprecated get_any method allowed workflows to proceed even with missing or null values, providing fault tolerance. The new get method is stricter and requires all variables to exist, resulting in unexpected failures for workflows that aren't explicitly handling missing inputs.

You are right. We allow the Optional variable in the START Node to be empty, but we don’t permit misreferenced variables in other cases. This refactoring is necessary to provide a more manageable and optimized user experience in the future.