Create new IamcDataFilter class (#360)

Co-authored-by: Philip Hackstock <[email protected]>

nomenclature/processor/iamc.py

@@ -0,0 +1,36 @@
+from typing import List
+from pydantic import BaseModel, field_validator
+
+from pyam import IAMC_IDX
+
+from nomenclature.definition import DataStructureDefinition
+
+
+class IamcDataFilter(BaseModel):
+    model: List[str] | None = None
+    scenario: List[str] | None = None
+    region: List[str] | None = None
+    variable: List[str] | None = None
+    unit: List[str] | None = None
+    year: List[int] | None = None
+
+    @field_validator("*", mode="before")
+    @classmethod
+    def single_input_to_list(cls, v):
+        return v if isinstance(v, list) else [v]
+
+    def validate_with_definition(self, dsd: DataStructureDefinition) -> None:
+        error_msg = ""
+
+        # check for filter-items that are not defined in the codelists
+        for dimension in IAMC_IDX:
+            if codelist := getattr(dsd, dimension, None) is None:
+                continue
+            if invalid := codelist.validate_items(getattr(self, dimension) or []):
+                error_msg += (
+                    f"The following {dimension}s were not found in the "
+                    f"DataStructureDefinition:\n{invalid}\n"
+                )
+
+        if error_msg:
+            raise ValueError(error_msg)

nomenclature/processor/required_data.py

@@ -49,6 +49,7 @@ class RequiredData(BaseModel):
     variable: List[str] | None = None
     region: List[str] | None = None
     year: List[int] | None = None
+    # TODO consider merging with IamcDataFilter
 
     @field_validator("measurand", "region", "year", "variable", mode="before")
     @classmethod