[azure-ai-ml] Fix deployment_templates.list(name=...) crashing on stringified settings

[swarupecenits]

Notes

• Fixes internal bug #5402672: deployment_templates.list(name=...) raised AttributeError: 'str' object has no attribute 'request_timeout' and never returned any versions.
• Root cause: get() and list() return different shapes. In the list() response, requestSettings / livenessProbe / readinessProbe arrive as stringified dicts nested under properties, whereas get() returns typed objects at the top level. _from_rest_object passed those raw strings straight to the attribute-based converters (OnlineRequestSettings._from_rest_object / ProbeSettings._from_rest_object), which then failed on settings.request_timeout.
• Fix: added a small _coerce_rest_settings(value, rest_cls) helper that parses the stringified dict and wraps it into the typed REST model before conversion. Already-typed values (the get() shape) short-circuit unchanged, so that path is untouched. Applied to request_settings, liveness_probe, and readiness_probe.
• This mirrors the existing "parse stringified properties" handling already present in _from_rest_object for tags / environment_variables / allowed_instance_types, and brings list() to parity with models.list() / environments.list().

Testing

• Added test_deployment_template_from_rest_object_list_shape_stringified_settings - feeds the real list() shape (stringified requestSettings / livenessProbe / readinessProbe) and asserts they are parsed (e.g. request_timeout_ms == 90000, probe thresholds populated).
• Added test_deployment_template_from_rest_object_get_shape_typed_settings - asserts the already-working get() shape (typed settings object) still converts correctly.
• Verified live against the azure-huggingface registry: deployment_templates.list(name=...) now returns the template versions (parity with models.list()), and the reporter's suggested acceptance test passes.
• Full deployment_template unit tests pass; black and isort clean.

Description

Fixes internal bug #5402672. deployment_templates.list(name=...) no longer raises AttributeError: 'str' object has no attribute 'request_timeout' and now returns an iterable of DeploymentTemplate versions, consistent with models.list() / environments.list(). The list response nests settings (requestSettings / livenessProbe / readinessProbe) as stringified dicts under properties; these are now parsed and wrapped into the typed REST models before conversion, while the get() path (already-typed objects) is left unchanged.

All SDK Contribution checklist:

• The pull request does not introduce [breaking changes]
• CHANGELOG is updated for new features, bug fixes or other significant changes.
• I have read the contribution guidelines.

Verification

All checks below were run against the live azure-huggingface registry (and the in-repo unit tests), on the branch with this fix.

1. Repro - the crash is gone, list(name=...) now returns versions

deployment_templates.list(name=...) previously raised AttributeError: 'str' object has no attribute 'request_timeout'. It now returns the template versions (v5, v3, v2), with models.list() shown as the working control for parity.

2. Reporter's suggested acceptance test - passing

The acceptance test from the bug report passes: test_list_by_name_returns_versions and test_list_by_name_parity_with_models.

3. In-repo unit tests - passing

The deployment_template unit test suite passes, including the added coverage for the list() (stringified settings) and get() (typed settings) shapes.

Testing Guidelines

• Pull request includes test coverage for the included changes.

[Copilot]

Pull request overview

This PR fixes internal bug #5402672 where deployment_templates.list(name=...) in azure-ai-ml raised AttributeError: 'str' object has no attribute 'request_timeout' and returned no versions. The root cause is that the list() response nests requestSettings / livenessProbe / readinessProbe as stringified dicts under properties, while get() returns typed objects at the top level. The fix adds a _coerce_rest_settings helper that parses the stringified dict and wraps it into the typed REST model before the existing attribute-based converters run, bringing list() to parity with models.list() / environments.list().

Changes:

• Added _coerce_rest_settings(value, rest_cls) helper and applied it to request_settings, liveness_probe, and readiness_probe in DeploymentTemplate._from_rest_object, short-circuiting already-typed (get()) values unchanged.
• Added regression tests for both the list() (stringified) and get() (typed) shapes.
• Added a CHANGELOG entry describing the bug fix.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
sdk/ml/azure-ai-ml/azure/ai/ml/entities/_deployment/deployment_template.py	Adds _coerce_rest_settings helper and coerces settings into typed REST models before conversion
sdk/ml/azure-ai-ml/tests/deployment_template/unittests/test_deployment_template.py	Adds regression tests for list/get shapes; contains duplicated test method definitions that shadow each other
sdk/ml/azure-ai-ml/CHANGELOG.md	Documents the deployment_templates.list(name=...) bug fix