Use a custom node ID format

Oct 13, 2025 by wbrum.org 16 views

Introduction

In a Home Assistant topology, the MAX_NODE_ID_LENGTH constant is used to determine the maximum length of node IDs. However, it appears that this constant is not being applied to group members, leading to unexpected behavior when working with devices that have long names. In this article, we will explore the issue, its implications, and potential solutions.

Understanding MAX_NODE_ID_LENGTH

The MAX_NODE_ID_LENGTH constant is a crucial setting in Home Assistant that determines the maximum length of node IDs. This constant is used to prevent node IDs from becoming too long and causing issues with the topology. By default, the MAX_NODE_ID_LENGTH is set to 16 characters, but it can be adjusted by modifying the defaults.const.MAX_NODE_ID_LENGTH variable.

The Issue

The problem arises when working with devices that have long names, such as the example provided:

defaults.const.MAX_NODE_ID_LENGTH: 18

groups:
  _ auto_create: True
  nodes:
    members: [ device-017-length ]

In this example, the MAX_NODE_ID_LENGTH is set to 18, but the node ID device-017-length still fails to be created due to the 16-character limit being applied to group member lists.

Implications

The failure to apply the MAX_NODE_ID_LENGTH constant to group members has several implications:

Inconsistent behavior: The inconsistent application of the MAX_NODE_ID_LENGTH constant can lead to unexpected behavior when working with devices that have long names.
Node ID creation issues: The failure to create node IDs due to the 16-character limit can cause issues with the topology, leading to errors and potential data loss.
Limited flexibility: The inability to adjust the MAX_NODE_ID_LENGTH constant for group members limits the flexibility of the topology and can make it more difficult to work with devices that have long names.

Potential Solutions

To address the issue, several potential solutions can be explored:

Adjust the MAX_NODE_ID_LENGTH constant: Modifying the defaults.const.MAX_NODE_ID_LENGTH variable to a higher value, such as 20 or 25, can help to prevent node ID creation issues.
Use a custom node ID format: Using a custom node ID format that takes into account the MAX_NODE_ID_LENGTH constant can help to prevent issues with long node IDs.
Implement a workaround: Implementing a workaround, such as using a separate variable to store the node ID, can help to bypass the 16-character limit and prevent node ID creation issues.

Conclusion

The failure to apply the MAX_NODE_ID_LENGTH constant to group members is a significant issue that can lead to inconsistent behavior, node ID creation issues, and limited flexibility. By exploring potential solutions, such as adjusting the MAX_NODE_ID_LENGTH constant, using a custom node ID format, or implementing a workaround, users can help to prevent these issues and ensure a more stable and flexible topology.

Recommendations

To prevent node ID creation issues and ensure a more stable and flexible topology, we recommend the following:

Adjust the MAX_NODE_ID_LENGTH constant: Modify the defaults.const.MAX_NODE_ID_LENGTH variable to a higher value, such as 20 or 25, to prevent node ID creation issues.
Use a custom node ID format: Use a custom node ID format that takes into account the MAX_NODE_ID_LENGTH constant to prevent issues with long node IDs.
Implement a workaround: Implement a workaround, such as using a separate variable to store the node ID, to bypass the 16-character limit and prevent node ID creation issues.

By following these recommendations, users can help to prevent node ID creation issues and ensure a more stable and flexible topology.

Future Development

To address the issue and provide a more stable and flexible topology, we recommend the following:

Improve the MAX_NODE_ID_LENGTH constant: Improve the MAX_NODE_ID_LENGTH constant to take into account the group member list and prevent node ID creation issues.
Implement a more flexible node ID format: Implement a more flexible node ID format that can accommodate long node IDs and prevent issues with the topology.
Provide a workaround: Provide a workaround, such as a separate variable to store the node ID, to bypass the 16-character limit and prevent node ID creation issues.

Frequently Asked Questions

In this article, we will address some of the most frequently asked questions related to the MAX_NODE_ID_LENGTH constant not being applied to group members.

Q: What is the MAX_NODE_ID_LENGTH constant?

A: The MAX_NODE_ID_LENGTH constant is a setting in Home Assistant that determines the maximum length of node IDs. This constant is used to prevent node IDs from becoming too long and causing issues with the topology.

Q: Why is the MAX_NODE_ID_LENGTH constant not being applied to group members?

A: The MAX_NODE_ID_LENGTH constant is not being applied to group members because of a bug in the Home Assistant topology. This bug causes the 16-character limit to be applied to group member lists instead of the MAX_NODE_ID_LENGTH constant.

Q: What are the implications of the MAX_NODE_ID_LENGTH constant not being applied to group members?

A: The failure to apply the MAX_NODE_ID_LENGTH constant to group members has several implications, including:

Inconsistent behavior: The inconsistent application of the MAX_NODE_ID_LENGTH constant can lead to unexpected behavior when working with devices that have long names.
Node ID creation issues: The failure to create node IDs due to the 16-character limit can cause issues with the topology, leading to errors and potential data loss.
Limited flexibility: The inability to adjust the MAX_NODE_ID_LENGTH constant for group members limits the flexibility of the topology and can make it more difficult to work with devices that have long names.

Q: How can I prevent node ID creation issues?

A: To prevent node ID creation issues, you can try the following:

Adjust the MAX_NODE_ID_LENGTH constant: Modify the defaults.const.MAX_NODE_ID_LENGTH variable to a higher value, such as 20 or 25, to prevent node ID creation issues.
Use a custom node ID format: Use a custom node ID format that takes into account the MAX_NODE_ID_LENGTH constant to prevent issues with long node IDs.
Implement a workaround: Implement a workaround, such as using a separate variable to store the node ID, to bypass the 16-character limit and prevent node ID creation issues.

Q: What are some potential solutions to the MAX_NODE_ID_LENGTH constant not being applied to group members?

A: Some potential solutions to the MAX_NODE_ID_LENGTH constant not being applied to group members include:

Improving the MAX_NODE_ID_LENGTH constant: Improve the MAX_NODE_ID_LENGTH constant to take into account the group member list and prevent node ID creation issues.
Implementing a more flexible node ID format: Implement a more flexible node ID format that can accommodate long node IDs and prevent issues with the topology.
Providing a workaround: Provide a workaround, such as a separate variable to store the node ID, to bypass the 16-character limit and prevent node ID creation issues.

Q: How can I report a bug related to the MAX_NODE_ID_LENGTH constant not being applied to group members?

A: To report a bug related to the MAX_NODE_ID_LENGTH constant not being applied to group members, you can follow these steps:

Check the Home Assistant documentation: Check the Home Assistant documentation to see if the issue is already documented.
Search for existing issues: Search for existing issues on the Home Assistant GitHub page to see if someone else has already reported the issue.
Create a new issue: If you cannot find an existing issue, create a new issue on the Home Assistant GitHub page and provide as much detail as possible about the issue.

Conclusion

The failure to apply the MAX_NODE_ID_LENGTH constant to group members is a significant issue that can lead to inconsistent behavior, node ID creation issues, and limited flexibility. By understanding the implications of this issue and exploring potential solutions, users can help to prevent these issues and ensure a more stable and flexible topology.

Recommendations

To prevent node ID creation issues and ensure a more stable and flexible topology, we recommend the following:

Adjust the MAX_NODE_ID_LENGTH constant: Modify the defaults.const.MAX_NODE_ID_LENGTH variable to a higher value, such as 20 or 25, to prevent node ID creation issues.
Use a custom node ID format: Use a custom node ID format that takes into account the MAX_NODE_ID_LENGTH constant to prevent issues with long node IDs.
Implement a workaround: Implement a workaround, such as using a separate variable to store the node ID, to bypass the 16-character limit and prevent node ID creation issues.

By following these recommendations, users can help to prevent node ID creation issues and ensure a more stable and flexible topology.