[resolved] embelish resolver exceptions

Author: alangenfeld

python_modules/libraries/dagster-components/dagster_components/resolved/context.py

@@ -13,6 +13,8 @@
 from jinja2.exceptions import UndefinedError
 from jinja2.nativetypes import NativeTemplate
 
+from dagster_components.resolved.model import ResolvableModel
+
 T = TypeVar("T")
 
 
@@ -91,6 +93,24 @@ def _scope_threw_exc(self, fmt_exc: list[str]):
 
         return ResolutionException("".join(msg_parts))
 
+    def build_resolve_fn_exc(
+        self,
+        fmt_exc: list[str],
+        field_name: str,
+        model: ResolvableModel,
+    ) -> ResolutionException:
+        msg_parts = []
+        loc = self._location()
+        if loc:
+            msg_parts.append(loc + "\n")
+
+        msg_parts.append(
+            f"Exception occurred in Resolver for field '{field_name}' resolving from {model.__class__.__name__}({model}).\n"
+        )
+        msg_parts.extend(fmt_exc)
+
+        return ResolutionException("".join(msg_parts))
+
     def _resolve_inner_value(self, val: Any) -> Any:
         """Resolves a single value, if it is a templated string."""
         if isinstance(val, str):

python_modules/libraries/dagster-components/dagster_components/resolved/model.py

@@ -1,3 +1,5 @@
+import sys
+import traceback
 from abc import ABC, abstractmethod
 from collections.abc import Mapping, Sequence
 from dataclasses import dataclass
@@ -305,14 +307,26 @@ def from_model(fn: Callable[["ResolutionContext", Any], Any]):
         """Resolve this field by invoking the function which will receive the entire parent ResolvableModel."""
         return Resolver(ParentFn(fn))
 
-    def execute(self, context: "ResolutionContext", model: ResolvableModel, field_name: str) -> Any:
-        if isinstance(self.fn, ParentFn):
-            return self.fn.callable(context, model)
-        elif isinstance(self.fn, AttrWithContextFn):
-            attr = getattr(model, field_name)
-            return self.fn.callable(context.at_path(field_name), attr)
-        else:
-            raise ValueError(f"Unsupported DSLFieldResolver type: {self.fn}")
+    def execute(
+        self,
+        context: "ResolutionContext",
+        model: ResolvableModel,
+        field_name: str,
+    ) -> Any:
+        try:
+            if isinstance(self.fn, ParentFn):
+                return self.fn.callable(context, model)
+            elif isinstance(self.fn, AttrWithContextFn):
+                attr = getattr(model, field_name)
+                return self.fn.callable(context.at_path(field_name), attr)
+        except Exception:
+            raise context.build_resolve_fn_exc(
+                traceback.format_exception(*sys.exc_info()),
+                field_name=field_name,
+                model=model,
+            )
+
+        raise ValueError(f"Unsupported DSLFieldResolver type: {self.fn}")
 
 
 ResolvedType: TypeAlias = Union[type[ResolvedKwargs], type[ResolvedFrom]]

python_modules/libraries/dagster-components/dagster_components/test/basic_components.py

@@ -4,12 +4,12 @@
 
 from collections.abc import Mapping
 from dataclasses import dataclass
-from typing import Any
+from typing import Annotated, Any
 
 from dagster._core.definitions.definitions_class import Definitions
 from pydantic import BaseModel, ConfigDict
 
-from dagster_components import Component, ResolvableModel, ResolvedFrom
+from dagster_components import Component, ResolvableModel, ResolvedFrom, Resolver
 from dagster_components.core.component import ComponentLoadContext
 
 
@@ -24,12 +24,20 @@ def _error():
 class MyComponentModel(ResolvableModel):
     a_string: str
     an_int: int
+    throw: bool = False
+
+
+def _maybe_throw(ctx, throw):
+    if throw:
+        _error()
+    return throw
 
 
 @dataclass
 class MyComponent(Component, ResolvedFrom[MyComponentModel]):
     a_string: str
     an_int: int
+    throw: Annotated[bool, Resolver(_maybe_throw)]
 
     def build_defs(self, context: ComponentLoadContext) -> Definitions:
         return Definitions()

python_modules/libraries/dagster-components/dagster_components_tests/integration_tests/components/validation/basic_component_resolve_exc/component.yaml

@@ -0,0 +1,6 @@
+type: .MyComponent
+
+attributes:
+  a_string: "hi"
+  an_int: 3
+  throw: true

python_modules/libraries/dagster-components/dagster_components_tests/integration_tests/validation_tests/test_component_validation.py

@@ -37,6 +37,16 @@
             "_inner_error()",
         ),
     ),
+    ComponentValidationTestCase(
+        component_path="validation/basic_component_resolve_exc",
+        component_type_filepath=BASIC_COMPONENT_TYPE_FILEPATH,
+        should_error=True,
+        validate_error_msg=msg_includes_all_of(
+            "component.yaml:6",
+            'raise Exception("boom")',
+            "_inner_error()",
+        ),
+    ),
 ]