Connection and variables are lost when block changes are made

[sotono-046]

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Dify version

0.14.1

Cloud or Self Hosted

Cloud

Steps to reproduce

• Create a new block, any type is acceptable
• Set variables in the block and make it have connections to other blocks
• Select “Change Block” from the context menu
• The existing block is replaced by the new block of your choice.
• The variables set in the existing block and its connections to other blocks will be deleted.

✔️ Expected Behavior

• Preserves the connection between the variable and the block when the block is changed
• If variables are difficult, keep the connection
• (If it is not compatible, there should be no connection)

❌ Actual Behavior

• The variables set in the existing block and its connections to other blocks will be deleted.

[dosubot]

Hello @sotono-046! 👋 I'm here to help you with bugs, questions, and becoming a contributor. I'm Dosu, a bot designed to assist you while you wait for a human maintainer.

The issue you're experiencing, where connections and variables are lost when a block is changed, seems to be related to how Dify handles block changes. Currently, there isn't specific documentation or code comments in the Dify codebase that explain the rationale behind deleting connections when a block is changed. However, the logic for handling variable preservation when a block is changed involves checking for affected nodes and updating them if a variable's name changes ^[1].

To address this issue, you might consider implementing a mechanism that checks for compatibility between the old and new block types before deciding whether to preserve or delete connections and variables. This could involve:

1. Compatibility Check: Before changing a block, check if the new block type is compatible with the existing connections and variables. If compatible, preserve them.

2. Preservation Logic: Implement logic to update the connections and variables to fit the new block type, if possible.

3. User Confirmation: If compatibility cannot be ensured, prompt the user to confirm the deletion of connections and variables.

These steps could help in maintaining the integrity of your workflow when blocks are changed.

To continue talking to Dosu, mention @dosu.

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[sotono-046]

Sorry, I checked but forgot to attach the recording of the actual behavior, here it is!

2024-12-20.204740.mp4

[crazywoola]

Preserves the connection between the variable and the block when the block is changed
If variables are difficult, keep the connection
(If it is not compatible, there should be no connection)

I think we decided to do this because the 3 items is too complicated to achieve.

The variables set in the existing block and its connections to other blocks will be deleted.