Null-safe Data Access

Across CLI/API payload handling, treat nullable fields and missing keys as first-class: normalize None before iterating/len’ing, use safe access for nested structures, and validate prerequisites early with clear user errors.

Coding standards 1) Normalize containers before iteration/length checks

• If a field can be None but you will iterate or call len(), convert it to an appropriate default ([] for iterables, {} for maps).

2) Use safe nested access for dict-based payloads

• Avoid direct payload['a']['b'] when a/b may be missing or None. Use .get() (or explicit guards) along the path.

3) Fallback when SDK models may surface nullable properties

• If an SDK returns typed objects where .properties (or similar) may be None, fall back to the raw response/payload rather than forcing access.

4) Don’t over-guard when upstream contracts already guarantee types

• Remove redundant checks that obscure intent. If upstream guarantees result is a dict, don’t add isinstance(result, dict) solely for safety.
• Where item-level shape is uncertain, guard at the item boundary (e.g., ensure item is a dict before calling .get()).

5) When null means “missing prerequisite,” raise a clear CLI error

• If required related state is absent (e.g., managed identity object needed for an MSI-related option; host names required unless --hostname is provided), validate and raise ArgumentUsageError/validation errors before calling the backend.

Example pattern

# 1) normalize before iteration
additional_info = json_obj.get('additionalInfo') or []
for x in additional_info:
    ...

# 2) safe nested dict access
vmss = vmss_result  # dict
storage_profile = vmss.get('virtualMachineProfile', {}).get('storageProfile')
if storage_profile is not None:
    storage_profile['imageReference'] = None

# 3) fallback when SDK returns None-able properties
keys = sdk_list_function_keys(...)
return keys.properties if keys.properties is not None else dict(keys)

# 4) explicit validation on prerequisite nulls
identity = webapp.get('identity')
if enable_using_msi and not identity:
    raise ArgumentUsageError(
        "--enable-using-msi requires a managed identity. Assign one with: ..."
    )

Applying these rules consistently prevents TypeError/KeyError from null containers, avoids opaque backend failures, and keeps null-handling intent explicit and reviewable.