Vue Flow Bug: Custom Node Handle & Edge Property Issues

Hey everyone, let's dive into a tricky bug I've been wrestling with in Vue Flow. It involves custom nodes, their handles, and how edge properties like sourcePosition and targetPosition behave. It's a bit technical, but I'll break it down so it's easy to follow.

The Bug: Handle Behavior with Custom Nodes

So, the problem centers around custom nodes in Vue Flow. When you create these custom nodes and add multiple handles (those little connection points), the edge properties don't always play nice. Specifically, the sourcePosition and targetPosition seem to default to the first handle defined, ignoring subsequent ones. This leads to some unexpected edge connections, and generally makes it harder to work with complex node setups. This is a significant issue if you're building something where the precise connection points are critical.

In the current behavior, when you define a custom node and set up multiple handles, the edges tend to connect only to the first available handle. This means that even if you specify different sourcePosition or targetPosition properties for the edges, they are ignored, which could lead to a buggy and unreliable user experience.

Imagine this: You've got a node with multiple input and output points. You meticulously define the positions of each handle, expecting the edges to connect accordingly. But nope! The edges stubbornly attach to the first handle, creating a mess of connections. This behavior is definitely not what we want. You know what I mean, right? We want those edges to connect where we tell them to.

Current Behavior in Vue Flow

Currently, when using custom nodes and defining multiple handles, the edge properties sourcePosition and targetPosition don't seem to work as expected. The edges tend to connect to the first handle, even if other positions are specified. This behavior leads to the unexpected connection which in turn could cause confusion to the end-users.

This can be frustrating, particularly in complex diagrams or applications where precise edge positioning is essential. When you have many nodes and connections, you expect the visualization to be clear and the connections to be accurate.

This is a common issue, particularly when people are building sophisticated node graphs. In these cases, precise placement is critical for the user to understand the flow of information or the relationships between elements. So, you can imagine the frustration when things don't connect where they should!

Expected Behavior

We'd expect the edge properties, like sourcePosition and targetPosition, to respect the handle positions we define. That means, when you set up a custom node with multiple handles and then create edges, the edges should connect to the handles based on the sourcePosition and targetPosition properties specified. This will enable more flexible and accurate diagrams.

Essentially, the expected behavior is that if you define a custom node with multiple handles, the edges should connect to the handle positions that are specified when creating the edges, not just the first handle by default.

This gives you full control over the connection points, leading to cleaner and more understandable diagrams. For example, if you're creating a data flow diagram, you'll want the connections to accurately represent the flow of data.

Why This Matters

Why is this bug a big deal, you ask? Well, precise handle positioning is crucial for a few reasons:

• Clear Visualization: It makes your diagrams easier to understand at a glance. No more spaghetti connections!
• User Experience: Accurate connections improve usability. Users can quickly see how things are connected.
• Complex Diagrams: It's essential for building complex diagrams where precision is key, such as data flow diagrams or network visualizations.

Steps to Reproduce (In theory)

Unfortunately, there isn't a specific, step-by-step guide to reproduce the issue (that was in the original report). However, the steps would generally involve the following:

1. Create a custom node in Vue Flow.
2. Add multiple handles to that custom node.
3. Create an edge and set its sourcePosition or targetPosition properties to a handle other than the first one.
4. Observe that the edge connects to the first handle, ignoring your specified position.

Further Investigation

To really nail down the issue, we'd need a minimal reproduction case (like a CodeSandbox link). This would help pinpoint the exact cause and allow the Vue Flow developers to fix it.

Potential Solutions

While a definitive solution depends on the root cause, some possible approaches include:

• Reviewing the Handle Logic: The Vue Flow code that handles edge connections may need to be adjusted to correctly interpret sourcePosition and targetPosition with multiple handles.
• Handle Indexing: Ensure that handle positions are properly indexed and used when creating edges.
• Component Updates: Make sure that the custom node component is correctly updating and passing the handle positions to the edge components.

Conclusion

This bug highlights the need for precise control over edge connections in Vue Flow. It's essential for creating clear, user-friendly diagrams, and will likely be addressed in a future update.

As the community grows, these bugs are identified and fixed. Hopefully, this one gets resolved quickly so that everyone can enjoy the power of Vue Flow with more precision and control.

In a nutshell: This bug makes it difficult to position edges correctly when you have custom nodes with multiple handles. It's something that needs attention to ensure Vue Flow remains a top-notch tool for creating visual diagrams.

For more information about Vue Flow, you can check out their official documentation. Vue Flow Documentation. And if you want to dig into how to create custom nodes, check out this guide from the Vue Flow team Creating Custom Nodes