feat: add ctx.validate()

beet/toolchain/config.py

@@ -22,6 +22,7 @@
 from beet.core.utils import FileSystemPath, JsonDict, TextComponent
 
 from .pipeline import FormattedPipelineException
+from .utils import format_validation_error
 
 
 class InvalidProjectConfig(FormattedPipelineException):
@@ -203,16 +204,6 @@ def config_error_handler(path: FileSystemPath = "<unknown>"):
     except FileNotFoundError as exc:
         raise InvalidProjectConfig(f"{path}: File not found.") from exc
     except ValidationError as exc:
-        errors = [
-            (
-                "config" + "".join(json.dumps([item]) for item in error["loc"]),
-                error["msg"].capitalize(),
-            )
-            for error in exc.errors()
-        ]
-        width = max(len(loc) for loc, _ in errors) + 1
-        message = f"{path}: Validation error.\n\n" + "\n".join(
-            "{loc:<{width}} => {msg}.".format(loc=loc, width=width, msg=msg)
-            for loc, msg in errors
-        )
+        message = f"{path}: Validation error.\n\n"
+        message += format_validation_error("config", exc)
         raise InvalidProjectConfig(message) from exc

beet/toolchain/context.py

@@ -5,6 +5,7 @@
     "ProjectCache",
     "Context",
     "ContextContainer",
+    "InvalidContextOptions",
 ]
 
 
@@ -15,25 +16,50 @@
 from pathlib import Path
 from typing import Any, Callable, List, Optional, Set, Tuple, TypeVar, overload
 
+from pydantic import ValidationError
+
 from beet.core.cache import MultiCache
 from beet.core.container import Container
 from beet.core.utils import FileSystemPath, JsonDict, TextComponent, extra_field
 from beet.library.data_pack import DataPack
 from beet.library.resource_pack import ResourcePack
 
 from .generator import Generator
-from .pipeline import GenericPipeline, GenericPlugin, GenericPluginSpec
+from .pipeline import (
+    FormattedPipelineException,
+    GenericPipeline,
+    GenericPlugin,
+    GenericPluginSpec,
+    PipelineFallthroughException,
+)
 from .template import TemplateManager
 from .tree import generate_tree
-from .utils import import_from_string
+from .utils import format_validation_error, import_from_string
 from .worker import WorkerPoolHandle
 
-InjectedType = TypeVar("InjectedType")
+T = TypeVar("T")
 
 Plugin = GenericPlugin["Context"]
 PluginSpec = GenericPluginSpec["Context"]
 
 
+class InvalidContextOptions(FormattedPipelineException):
+    """Raised when validating context metadata."""
+
+    key: str
+    explanation: Optional[str]
+
+    def __init__(self, key: str, explanation: Optional[str] = None):
+        super().__init__(key, explanation)
+        self.key = key
+        self.explanation = explanation
+        self.message = f"Invalid context options {key!r}."
+        self.format_cause = True
+
+        if explanation:
+            self.message += f"\n\n{explanation}"
+
+
 @dataclass
 class Pipeline(GenericPipeline["Context"]):
     ctx: "Context"
@@ -116,7 +142,7 @@ def __post_init__(self, whitelist: Optional[List[str]]):
         self.template.expose("parse_json", lambda string: json.loads(string))
 
     @overload
-    def inject(self, cls: Callable[["Context"], InjectedType]) -> InjectedType:
+    def inject(self, cls: Callable[["Context"], T]) -> T:
         ...
 
     @overload
@@ -174,6 +200,18 @@ def override(self, **meta: Any):
                 del self.meta[key]
             self.meta.update(to_restore)
 
+    def validate(self, key: str, validator: Callable[..., T]) -> T:
+        """Validate context metadata."""
+        try:
+            return validator(**self.meta.get(key, {}))
+        except ValidationError as exc:
+            explanation = format_validation_error(key, exc)
+            raise InvalidContextOptions(key, explanation) from None
+        except PipelineFallthroughException:
+            raise
+        except Exception as exc:
+            raise InvalidContextOptions(key) from exc
+
     @property
     def packs(self) -> Tuple[ResourcePack, DataPack]:
         return self.assets, self.data

beet/toolchain/utils.py

@@ -4,6 +4,7 @@
     "stable_hash",
     "format_obj",
     "format_exc",
+    "format_validation_error",
     "import_from_string",
     "locate_minecraft",
     "ensure_builtins",
@@ -21,6 +22,7 @@
 
 from base58 import b58encode
 from fnvhash import fnv1a_32, fnv1a_64
+from pydantic import ValidationError
 
 HASH_ALPHABET = b"123456789abcdefghijkmnopqrstuvwxyz"
 
@@ -58,6 +60,21 @@ def format_obj(obj: Any) -> str:
     return repr(f"{module}.{name}") if module and name else repr(obj)
 
 
+def format_validation_error(prefix: str, exc: ValidationError) -> str:
+    errors = [
+        (
+            prefix + "".join(json.dumps([item]) for item in error["loc"]),
+            error["msg"].capitalize(),
+        )
+        for error in exc.errors()
+    ]
+    width = max(len(loc) for loc, _ in errors) + 1
+    return "\n".join(
+        "{loc:<{width}} => {msg}.".format(loc=loc, width=width, msg=msg)
+        for loc, msg in errors
+    )
+
+
 def import_from_string(
     dotted_path: str,
     default_member: Optional[str] = None,

examples/code_validate/beet.json

@@ -0,0 +1,9 @@
+{
+  "pipeline": ["demo"],
+  "meta": {
+    "demo": {
+      "message": "hello",
+      "repeat": 7
+    }
+  }
+}

examples/code_validate/demo.py

@@ -0,0 +1,14 @@
+from pydantic import BaseModel
+
+from beet import Context, Function
+
+
+class DemoOptions(BaseModel):
+    message: str
+    repeat: int
+
+
+def beet_default(ctx: Context):
+    config = ctx.validate("demo", DemoOptions)
+
+    ctx.data["demo:foo"] = Function([f"say {config.message}"] * config.repeat)

tests/snapshots/examples__build_code_validate__0.data_pack/data/demo/functions/foo.mcfunction

@@ -0,0 +1,7 @@
+say hello
+say hello
+say hello
+say hello
+say hello
+say hello
+say hello

tests/snapshots/examples__build_code_validate__0.data_pack/pack.mcmeta

@@ -0,0 +1,6 @@
+{
+  "pack": {
+    "pack_format": 7,
+    "description": ""
+  }
+}

tests/snapshots/examples__build_code_validate__1.resource_pack/pack.mcmeta

@@ -0,0 +1,6 @@
+{
+  "pack": {
+    "pack_format": 7,
+    "description": ""
+  }
+}