`AttributeError: 'str' object has no attribute 'joinpath'` in dagster-dbt

[dgrozenok]

What's the issue?

Summary

When running dagster-dbt integration with the DbtProjectComponent, the execution fails with AttributeError: 'str' object has no attribute 'joinpath' when dagster tries to attach SQL model code references.

Environment

• dagster: >=1.11.13
• dagster-dbt: >=0.28.1
• Python: 3.13
• dbt-core: >=1.10.13
• dbt-trino: >=1.9.3

Error Stacktrace

AttributeError: 'str' object has no attribute 'joinpath'
  File "/var/lang/lib/python3.13/site-packages/dagster_dbt/dagster_dbt_translator.py", line 725, in _attach_sql_model_code_reference
    abs_path = project.project_dir.joinpath(relative_path).resolve()
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Full stack trace:

AttributeError: 'str' object has no attribute 'joinpath'
  File "/var/lang/lib/python3.13/site-packages/dagster/_core/execution/plan/utils.py", line 57, in op_execution_error_boundary
    yield
  File "/var/lang/lib/python3.13/site-packages/dagster/_utils/__init__.py", line 394, in iterate_with_context
    next_output = next(iterator)
  File "/var/lang/lib/python3.13/site-packages/dagster_dbt/components/dbt_project/component.py", line 401, in _fn
    yield from self.execute(context=context, dbt=DbtCliResource(project))
  File "/var/lang/lib/python3.13/site-packages/dagster_dbt/components/dbt_project/component.py", line 486, in execute
    yield from self._get_dbt_event_iterator(context, dbt)
  File "/var/lang/lib/python3.13/site-packages/dagster_dbt/core/dbt_event_iterator.py", line 215, in __next__
    return next(self._inner_iterator)
  File "/var/lang/lib/python3.13/site-packages/dagster_dbt/core/dbt_cli_invocation.py", line 289, in _stream_asset_events
    yield from event.to_default_asset_events(
        manifest=self.manifest,
        dagster_dbt_translator=self.dagster_dbt_translator,
        context=self.context,
        target_path=self.target_path,
        project=self.project,
    )
  File "/var/lang/lib/python3.13/site-packages/dagster_dbt/core/dbt_cli_event.py", line 570, in to_default_asset_events
    yield from self._to_model_events(
        manifest, dagster_dbt_translator, context, target_path, project
    )
  File "/var/lang/lib/python3.13/site-packages/dagster_dbt/core/dbt_cli_event.py", line 392, in _to_model_events
    asset_key = dagster_dbt_translator.get_asset_spec(manifest, self._unique_id, project).key
  File "/var/lang/lib/python3.13/site-packages/dagster_dbt/components/dbt_project/component.py", line 532, in get_asset_spec
    base_spec = super().get_asset_spec(manifest, unique_id, project)
  File "/var/lang/lib/python3.13/site-packages/dagster/components/utils/translation.py", line 220, in get_asset_spec
    return self._shim_method("get_asset_spec")(*args, **kwargs)
  File "/var/lang/lib/python3.13/site-packages/dagster_dbt/dagster_dbt_translator.py", line 150, in get_asset_spec
    asset=self.get_asset_spec(manifest, upstream_id, project).key,
  File "/var/lang/lib/python3.13/site-packages/dagster_dbt/components/dbt_project/component.py", line 532, in get_asset_spec
    base_spec = super().get_asset_spec(manifest, unique_id, project)
  File "/var/lang/lib/python3.13/site-packages/dagster/components/utils/translation.py", line 220, in get_asset_spec
    return self._shim_method("get_asset_spec")(*args, **kwargs)
  File "/var/lang/lib/python3.13/site-packages/dagster_dbt/dagster_dbt_translator.py", line 210, in get_asset_spec
    metadata=_attach_sql_model_code_reference(
        existing_metadata=spec.metadata,
        dbt_resource_props=resource_props,
        project=project,
    )
  File "/var/lang/lib/python3.13/site-packages/dagster_dbt/dagster_dbt_translator.py", line 725, in _attach_sql_model_code_reference
    abs_path = project.project_dir.joinpath(relative_path).resolve()
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^

What did you expect to happen?

When DbtProject is retrieved from metadata, the project_dir field should be a Path object, not a string, so that methods like joinpath() can be called on it.

How to reproduce?

defs.yaml:

type: dagster_dbt.DbtProjectComponent

attributes:
  project: '{{ project_root }}/path/to/dbt/project'
  cli_args:
    - run

1. Set up a dagster-dbt project with DbtProjectComponent
2. Configure it to run a subset of dbt models
3. Run the asset that depends on Python assets and dbt models
4. The error occurs when dagster tries to attach code references to the dbt models

Dagster version

dagster, version 1.12.3

Deployment type

Local

Deployment details

No response

Additional information

Root Cause Analysis

The issue occurs when DbtProject is stored in and retrieved from Dagster asset metadata. Here's the flow:

1. Storage: In dagster_dbt_translator.py (line 200), the DbtProject object is stored in asset metadata:

   **({DAGSTER_DBT_PROJECT_METADATA_KEY: project} if project else {})

2. Serialization: When Dagster serializes the metadata, Path objects in the DbtProject are converted to strings (standard Python/JSON serialization behavior).

3. Retrieval: In asset_utils.py (line 395), the project is retrieved from metadata:

   project = first_metadata.get(DAGSTER_DBT_PROJECT_METADATA_KEY)

4. Deserialized State: The retrieved project now has project_dir as a string instead of a Path object, because metadata serialization doesn't preserve Python types.

5. Error: When _attach_sql_model_code_reference() tries to call project.project_dir.joinpath(), it fails because project_dir is now a string.

The @record_custom decorator on DbtProject doesn't help here because the object is being serialized/deserialized through Dagster's metadata system, not through the record's own serialization.

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