fix: DCIM rack U count auto-update when adding/removing devices via C…

[ljluestc]

Fix: DCIM Rack Available U Count Auto-Update

Problem

GitHub Issue #676: DCIM cabinet available U count not automatically calculated when adding physical machines through CI relations.

Current Behavior

• Rack free_u_count is only updated when using the DCIM web interface (RackManager.add_device() / remove_device())
• When devices are added via regular CI relations, rack U counts remain unchanged
• Manual rack editing is required to recalculate available U space

Impact

Users must manually edit rack properties and save to trigger U count recalculation after adding devices, which is inefficient and error-prone.

Solution

Modified ci_relation_cache() and ci_relation_delete() functions in cmdb-api/api/tasks/cmdb.py to automatically detect and handle DCIM rack U count updates.

Technical Implementation

Files Changed:

• cmdb-api/api/tasks/cmdb.py (39 lines added)

Key Changes:

1. Added import: from api.lib.cmdb.const import BuiltinModelEnum
2. Enhanced ci_relation_cache() to detect DCIM rack + device relations
3. Enhanced ci_relation_delete() to detect DCIM rack + device relation removals
4. Automatic U count recalculation using existing RackManager.calc_u_free_count()

Code Logic

# Check if parent is a DCIM rack and child has U-related attributes
# If so, recalculate the rack's free U count
try:
    parent_ci = CI.get_by_id(parent_id)
    if parent_ci and parent_ci.ci_type.name == BuiltinModelEnum.DCIM_RACK:
        child_ci = api.lib.cmdb.ci.CIManager().get_ci_by_id(child_id, need_children=False)
        if child_ci and child_ci.get(RackBuiltinAttributes.U_START) is not None:
            # Recalculate rack free U count
            payload = {RackBuiltinAttributes.FREE_U_COUNT: RackManager.calc_u_free_count(parent_id)}
            api.lib.cmdb.ci.CIManager().update(parent_id, _sync=True, **payload)
            current_app.logger.info("Updated rack {} free U count after adding/removing device {}".format(parent_id, child_id))
except Exception as e:
    current_app.logger.warning("Failed to update DCIM rack U count: {}".format(e))

Trigger Conditions

• Parent CI: Must be DCIM rack (ci_type.name == 'dcim_rack')
• Child CI: Must have U attributes (u_start is not None)
• Result: Automatic rack free_u_count recalculation

[pycook]

Thanks for this contribution! I have a few suggestions to improve code quality:

1. Remove pr-description.md from the commit
2. Move imports to the top of the file
3. Avoid redundant module path when calling CIManager

Please update these points and I'll be happy to approve!