Issue with isValidConnection and Handling Same Handle Types in Custom Nodes

[Jarvis-Liu]

Description

I’ve encountered an issue with the isValidConnection implementation while working with custom nodes. Here’s the scenario:

1. I defined a custom node with two handles, setting their types to type: 'source' and type: 'target' respectively.
2. I created two instances of this node on the canvas and noticed that handles of the same type (e.g., source to source) can be connected. However, my intention is to allow only source to connect to target, similar to the behavior in the official demo with nodeType: 'default'. In the demo, if you try to connect source to source, the connection automatically redirects to the correct target handle.

I’m confused about why this behavior works seamlessly with nodeType: 'default' but not in my custom implementation. To address this, I attempted to use isValidConnection to validate the connection based on the handle types. However, I noticed that the connection parameter only provides the handle IDs, not their types. This forces me to look up the handle types by searching through the original data using the handle IDs, which feels overly cumbersome for a simple validation.

Questions/Suggestions

1. Would it be possible to enhance the connection parameter to include sourceHandleType and targetHandleType? This would make it much easier to validate connections without needing to manually map handle IDs to their types.
2. Alternatively, am I using isValidConnection incorrectly? Is there a more straightforward way to enforce source-to-target connections without resorting to manual lookups?

Any guidance or clarification on this would be greatly appreciated!

[bcakmakoglu]

You can set <VueFlow :connection-mode="ConnectionMode.Strict" ...> to get only allow source <--> target connections.

[Jarvis-Liu]

Thank you so much for your helpful answer! I tried it out and found it works exactly the same as using isValidConnection. 😊

Funny story - I actually noticed the 'connection-mode' this morning when consulting an AI, but it told me that setting it to 'Strict' would only allow 'one-to-one' connections, so I didn't actually try it in code. 🤷‍♂️

That said, I still hope the isValidConnection could enrich the handleType property to enable more diverse validation constraints.

If I may ask, is there a property that can achieve the auto-adjustment effect like the default node, which automatically aligns to the correct target/source?