Tables - LayerData - Drop sample and flag columns

This gets rid of columns sample_a|b|c and the flags column in favor of
storing three values for identical top and bottom height. The flags
column information will move to the comments. Also adding not-null and
index constraints for better data integrity.

Fixes #165

snowexsql/tables/layer_data.py

@@ -1,10 +1,10 @@
-from sqlalchemy import Column, Float, Integer, String, ForeignKey
+from sqlalchemy import Column, Float, ForeignKey, Integer, String, Text
 from sqlalchemy.orm import relationship
 
 from .base import Base
 from .doi import HasDOI
-from .measurement_type import HasMeasurementType
 from .instrument import HasInstrument
+from .measurement_type import HasMeasurementType
 
 
 class LayerData(
@@ -18,15 +18,11 @@ class LayerData(
     """
     __tablename__ = 'layers'
 
-    depth = Column(Float)
+    depth = Column(Float, nullable=False, index=True)
     pit_id = Column(String(50))
     bottom_depth = Column(Float)
-    comments = Column(String(1000))
-    sample_a = Column(String(20))
-    sample_b = Column(String(20))
-    sample_c = Column(String(20))
-    value = Column(String(50))
-    flags = Column(String(20))
+    comments = Column(Text)
+    value = Column(Text, nullable=False, index=True)
 
     # Link the site id with a foreign key
     site_id = Column(

tests/db_connection.py

@@ -123,8 +123,8 @@ def populated_layer(self, db):
             'geom': WKTElement(
                 "POINT(747987.6190615438 4324061.7062127385)", srid=26912
             ),
+            'depth': 100,
             'value': '42.5',
-            'sample_a': '42.5'
         }
         self._add_entry(
             db.url, LayerData, 'fakeinstrument', ["TEST"],

tests/factories/layer_data.py

@@ -17,8 +17,6 @@ class Meta:
     bottom_depth = 90.0
     comments = 'Layer comment'
     value = '40'
-    flags = 'Sample'
-    sample_a = '42'
 
     measurement_type = factory.SubFactory(
         MeasurementTypeFactory, name='Density', units='kg/m3'

tests/tables/test_layer_data.py

@@ -37,12 +37,6 @@ def test_comments_attribute(self):
     def test_value_attribute(self):
         assert self.subject.value == self.attributes.value
 
-    def test_sample_a_attribute(self):
-        assert self.subject.sample_a == self.attributes.sample_a
-
-    def test_flags_attribute(self):
-        assert self.subject.flags == self.attributes.flags
-
     def test_has_site(self):
         assert isinstance(self.subject.site, Site)
         assert self.subject.site.name == self.attributes.site.name