fix: allow null for Quantity.measure field

since apparently that is optional, e.g. for "Precipitation" quick form
logs

src/wuttafarm/db/alembic/versions/c30a725b54f9_allow_null_for_quantity_measure_id.py

@@ -0,0 +1,36 @@
+"""allow null for quantity.measure_id
+
+Revision ID: c30a725b54f9
+Revises: a240a1449de9
+Create Date: 2026-05-30 22:14:21.056993
+
+"""
+
+from typing import Sequence, Union
+
+from alembic import op
+import sqlalchemy as sa
+import wuttjamaican.db.util
+
+
+# revision identifiers, used by Alembic.
+revision: str = "c30a725b54f9"
+down_revision: Union[str, None] = "a240a1449de9"
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+
+    # quantity
+    op.alter_column(
+        "quantity", "measure_id", existing_type=sa.VARCHAR(length=20), nullable=True
+    )
+
+
+def downgrade() -> None:
+
+    # quantity
+    op.alter_column(
+        "quantity", "measure_id", existing_type=sa.VARCHAR(length=20), nullable=False
+    )

src/wuttafarm/db/model/quantities.py

@@ -109,7 +109,7 @@ class Quantity(model.Base):
     measure_id = sa.Column(
         sa.String(length=20),
         sa.ForeignKey("measure.drupal_id"),
-        nullable=False,
+        nullable=True,
         doc="""
         Measure for the quantity.
         """,
@@ -192,7 +192,12 @@ class Quantity(model.Base):
             app = config.get_app()
             value = app.render_quantity(value)
         units = str(self.units or "")
-        return f"( {measure} ) {value} {units}"
+
+        if measure:
+            return f"( {measure} ) {value} {units}"
+
+        label = self.label or ""
+        return f"{label} {value} {units}"
 
     def __str__(self):
         return self.render_as_text()

src/wuttafarm/web/views/quantities.py

@@ -298,7 +298,8 @@ class QuantityMasterView(WuttaFarmMasterView):
             f.remove("measure")
         else:
             f.set_readonly("measure")
-            f.set_default("measure", quantity.measure.name)
+            if quantity.measure:
+                f.set_default("measure", quantity.measure.name)
 
         # value
         if self.creating: