Use REAL for floating point columns if table is strict, closes #644

Refs #645

Author: simonw

docs/python-api.rst

@@ -1249,6 +1249,9 @@ If you pass a Python type, it will be mapped to SQLite types as shown here::
     np.float32: "FLOAT"
     np.float64: "FLOAT"
 
+.. note::
+    In sqlite-utils 3.x ``FLOAT`` is used for floating point columns when the correct column type is actually ``REAL``. If you specify ``strict=True`` tables created in strict mode will use the correct column type of ``REAL`` instead. We plan to change this behavior in ``sqlite-utils`` 4.x to always use ``REAL``, but this will represent a minor breaking change and so is being held for the next major release, see issue :issue:`645`.
+
 You can also add a column that is a foreign key reference to another table using the ``fk`` parameter:
 
 .. code-block:: python

sqlite_utils/db.py

@@ -938,10 +938,15 @@ def sort_key(p):
                         other_column=foreign_keys_by_column[column_name].other_column,
                     )
                 )
+            column_type_str = COLUMN_TYPE_MAPPING[column_type]
+            # Special case for strict tables to map FLOAT to REAL
+            # Refs https://github.com/simonw/sqlite-utils/issues/644
+            if strict and column_type_str == "FLOAT":
+                column_type_str = "REAL"
             column_defs.append(
                 "   [{column_name}] {column_type}{column_extras}".format(
                     column_name=column_name,
-                    column_type=COLUMN_TYPE_MAPPING[column_type],
+                    column_type=column_type_str,
                     column_extras=(
                         (" " + " ".join(column_extras)) if column_extras else ""
                     ),

tests/test_cli.py

@@ -2416,11 +2416,13 @@ def test_create_table_strict(strict):
         db = Database("test.db")
         result = runner.invoke(
             cli.cli,
-            ["create-table", "test.db", "items", "id", "integer"]
+            ["create-table", "test.db", "items", "id", "integer", "w", "float"]
             + (["--strict"] if strict else []),
         )
         assert result.exit_code == 0
         assert db["items"].strict == strict or not db.supports_strict
+        # Should have a floating point column
+        assert db["items"].columns_dict == {"id": int, "w": float}
 
 
 @pytest.mark.parametrize("method", ("insert", "upsert"))

tests/test_create.py

@@ -1350,8 +1350,12 @@ def test_insert_upsert_strict(fresh_db, method_name, strict):
 
 @pytest.mark.parametrize("strict", (False, True))
 def test_create_table_strict(fresh_db, strict):
-    table = fresh_db.create_table("t", {"id": int}, strict=strict)
+    table = fresh_db.create_table("t", {"id": int, "f": float}, strict=strict)
     assert table.strict == strict or not fresh_db.supports_strict
+    expected_schema = "CREATE TABLE [t] (\n" "   [id] INTEGER,\n" "   [f] FLOAT\n" ")"
+    if strict:
+        expected_schema = "CREATE TABLE [t] (\n   [id] INTEGER,\n   [f] REAL\n) STRICT"
+    assert table.schema == expected_schema
 
 
 @pytest.mark.parametrize("strict", (False, True))