Config context merging of objects #4506

New Issue

adam · 2025-12-29T18:36:49+01:00

adam commented

2025-12-29 18:36:49 +01:00

Originally created by @jchmielniak on GitHub (Jan 27, 2021).

Environment

Python version: 3.6.8
NetBox version: 2.10.3

Proposed Functionality

Cnfig contex are being merged as defined in documentation. Context with higher weight overwrites the lower.
This works good for contexts with simple JSON values. With object and list this behavior is not consistent.
JSON List follows merging like variables and JSON object are being merged to a new object including keys from both context.
This is w very practical but not documented feature. It would be good if lists could use the same merging schema.
We use merging of objects to add some additional items for a group of devices.
Fe: We set 2 DNS Server in Region, but for some devices we add a third one.

I am not sure it is a bug or feature.

Use Case

Functionality now:
Context A
{
"list": ["1", "2"],
"obj": {"one": "this"}
}
Context B
{
"list": ["10", "20"],
"obj": {"two": "that"}
}

Resulting context:
{
"list": ["1", "2"],
"obj": {
"one": "this",
"two": "that"
}
}

Expected context:
{
"list": ["1", "2", "10", "20"],
"obj": {
"one": "this",
"two": "that"
}
}

Database Changes

External Dependencies

Originally created by @jchmielniak on GitHub (Jan 27, 2021).  ### Environment * Python version: 3.6.8 * NetBox version: 2.10.3  ### Proposed Functionality Cnfig contex are being merged as defined in documentation. Context with higher weight overwrites the lower. This works good for contexts with simple JSON values. With object and list this behavior is not consistent. JSON List follows merging like variables and JSON object are being merged to a new object including keys from both context. This is w very practical but not documented feature. It would be good if lists could use the same merging schema. We use merging of objects to add some additional items for a group of devices. Fe: We set 2 DNS Server in Region, but for some devices we add a third one. I am not sure it is a bug or feature.  ### Use Case Functionality now: Context A { "list": ["1", "2"], "obj": {"one": "this"} } Context B { "list": ["10", "20"], "obj": {"two": "that"} } Resulting context: { "list": ["1", "2"], "obj": { "one": "this", "two": "that" } } Expected context: { "list": ["1", "2", "10", "20"], "obj": { "one": "this", "two": "that" } }  ### Database Changes  ### External Dependencies

adam added the status: under review label 2025-12-29 18:36:49 +01:00

adam closed this issue

2025-12-29 18:36:49 +01:00

adam commented

2025-12-29 18:36:49 +01:00

@jeremystretch commented on GitHub (Feb 4, 2021):

With object and list this behavior is not consistent.

The behavior is consistent, it's just not what you want. Each key within a higher-weight ConfigContext will overwrite the same key (if any) in a lower-weight ConfigContext, regardless of value type. This is by design, and allows us to reliably overwrite lists or dictionaries as needed. (For example, setting a global list of NTP servers, and overwriting it with a region-specific list.) Changing this would break the current behavior.

@jeremystretch commented on GitHub (Feb 4, 2021): > With object and list this behavior is not consistent. The behavior _is_ consistent, it's just not what you want. Each key within a higher-weight ConfigContext will overwrite the same key (if any) in a lower-weight ConfigContext, regardless of value type. This is by design, and allows us to reliably overwrite lists or dictionaries as needed. (For example, setting a global list of NTP servers, and overwriting it with a region-specific list.) Changing this would break the current behavior.

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Reference: starred/netbox#4506