analysis_method

core/lexicon.json

@@ -341,6 +341,9 @@
   {"categories": [{"name": "sample_method", "description": null}], "term": "pump", "definition": "pump"},
   {"categories": [{"name": "sample_method", "description": null}], "term": "thief sampler", "definition": "thief sampler"},
 
+  {"categories": [{"name": "analysis_method_type", "description": null}], "term": "Laboratory", "definition": "A procedure performed on a physical sample in a controlled, off-site laboratory environment. These methods typically involve complex instrumentation, standardized reagents, and formal quality control protocols."},
+  {"categories": [{"name": "analysis_method_type", "description": null}], "term": "Field Procedure", "definition": "A standardized procedure performed on-site at the time of sample collection. This can involve direct measurement of the environmental medium using a calibrated field instrument or a specific, documented technique for collecting a sample."},
+  {"categories": [{"name": "analysis_method_type", "description": null}], "term": "Calculation", "definition": "A mathematical procedure used to derive a new data point from one or more directly measured values. This type is used to document the provenance of calculated data, providing an auditable trail."},
 
   {"categories": [{"name": "organization", "description": null}], "term": "USGS", "definition": "US Geological Survey"},
   {"categories": [{"name": "organization", "description": null}], "term": "TWDB", "definition": "Texas Water Development Board"},

db/__init__.py

@@ -19,6 +19,7 @@
 from db.base import *
 from db.base import Base
 
+from db.analysis_method import *
 from db.asset import *
 from db.collabnet import *
 from db.contact import *

db/analysis_method.py

@@ -0,0 +1,45 @@
+"""
+This table is a citable library of abstract analytical methods and
+standardized field procedures.
+"""
+
+from typing import List, TYPE_CHECKING
+
+from sqlalchemy.orm import relationship, Mapped, mapped_column
+
+from db.base import Base, AutoBaseMixin, ReleaseMixin, lexicon_term
+
+if TYPE_CHECKING:
+    from db.observation import Observation
+
+
+class AnalysisMethod(Base, AutoBaseMixin, ReleaseMixin):
+    """
+    Represents a single, citable analytical method or standard procedure.
+    This is a lookup table.
+    """
+
+    # --- Columns ---
+    analysis_method_code: Mapped[str] = mapped_column(
+        nullable=True,
+        unique=True,
+        comment="The official code or identifier for the method (e.g., 'EPA 300.0').",
+    )
+    analysis_method_name: Mapped[str] = mapped_column(
+        nullable=False,
+        comment="The common, human-readable name of the method (e.g., Ion Chromatography for Anions).",
+    )
+    analysis_method_type: Mapped[str] = lexicon_term(
+        nullable=True,
+        comment="A controlled vocabulary field to categorize the method (e.g., 'Laboratory', 'Field Procedure', 'Calculation').",
+    )
+    source_organization: Mapped[str] = lexicon_term(
+        nullable=True,
+        comment="The organization that published the method (e.g., 'US EPA', 'USGS').",
+    )
+
+    # --- Relationships ---
+    # One-To-Many: An AnalysisMethod can be used for many Observations.
+    observations: Mapped[List["Observation"]] = relationship(
+        "Observation", back_populates="analysis_method"
+    )

db/observation.py

@@ -17,18 +17,27 @@
 from sqlalchemy import (
     ForeignKey,
     DateTime,
+    Integer,
 )
 from sqlalchemy.orm import mapped_column, relationship, Mapped
 
 from db.base import Base, AutoBaseMixin, ReleaseMixin, lexicon_term
 
+from typing import TYPE_CHECKING
+
+if TYPE_CHECKING:
+    from db.sample import Sample
+    from db.sensor import Sensor
+    from db.analysis_method import AnalysisMethod
+
 
 class Observation(Base, AutoBaseMixin, ReleaseMixin):
     __versioned__ = {}
 
     # NM_Aquifer fields for audits
     nma_pk_waterlevels: Mapped[str] = mapped_column(nullable=True)
 
+    # --- Foreign Keys ---
     sample_id: Mapped[int] = mapped_column(
         ForeignKey("sample.id", ondelete="CASCADE"),
         nullable=False,
@@ -37,7 +46,11 @@ class Observation(Base, AutoBaseMixin, ReleaseMixin):
         ForeignKey("sensor.id", ondelete="CASCADE"),
         nullable=True,
     )
+    analysis_method_id: Mapped[int] = mapped_column(
+        Integer, ForeignKey("analysis_method.id"), nullable=True
+    )
 
+    # --- Columns ---
     observation_datetime: Mapped[datetime] = mapped_column(
         DateTime(timezone=True), nullable=False, doc="Timestamp of the observation"
     )
@@ -63,12 +76,21 @@ class Observation(Base, AutoBaseMixin, ReleaseMixin):
         doc="Depth of the geothermal observation in feet",
     )
 
+    # --- Relationships ---
+    # Many-To-One: An Observation can be generated by one piece of Equipment.
     sensor: Mapped["Sensor"] = relationship(  # noqa: F821
         "Sensor", back_populates="observations", passive_deletes=True
     )  # noqa: F821
+
+    # Many-To-One: An Observation is derived from one Sample.
     sample: Mapped["Sample"] = relationship(  # noqa: F821
         "Sample", back_populates="observations", passive_deletes=True
     )  # noqa: F821
 
+    # Many-To-One: An Observation can be generated using one AnalysisMethod.
+    analysis_method: Mapped["AnalysisMethod"] = relationship(
+        "AnalysisMethod", back_populates="observations"
+    )
+
 
 # ============= EOF =============================================