Refactor sql_analyser into multiple classes for simpler extension in the future

django_migration_linter/sql_analyser/base.py

@@ -0,0 +1,109 @@
+# Copyright 2019 3YOURMIND GmbH
+
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+
+# http://www.apache.org/licenses/LICENSE-2.0
+
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import logging
+import re
+
+from .utils import update_migration_tests, build_error_dict
+
+logger = logging.getLogger(__name__)
+
+
+def has_not_null_column(sql_statements, **kwargs):
+    # TODO: improve to detect that the same column is concerned
+    return any(
+        re.search("(?<!DROP )NOT NULL", sql) and not sql.startswith("CREATE TABLE")
+        for sql in sql_statements
+    ) and not any("SET DEFAULT" in sql for sql in sql_statements)
+
+
+class BaseAnalyser(object):
+    base_migration_tests = [
+        {
+            "code": "RENAME_TABLE",
+            "fn": lambda sql, **kw: re.search("RENAME TABLE", sql)
+            or re.search("ALTER TABLE .* RENAME TO", sql),
+            "err_msg": "RENAMING tables",
+            "mode": "one_liner",
+        },
+        {
+            "code": "NOT_NULL",
+            "fn": has_not_null_column,
+            "err_msg": "NOT NULL constraint on columns",
+            "mode": "transaction",
+        },
+        {
+            "code": "DROP_COLUMN",
+            "fn": lambda sql, **kw: re.search("DROP COLUMN", sql),
+            "err_msg": "DROPPING columns",
+            "mode": "one_liner",
+        },
+        {
+            "code": "RENAME_COLUMN",
+            "fn": lambda sql, **kw: re.search("ALTER TABLE .* CHANGE", sql)
+            or re.search("ALTER TABLE .* RENAME COLUMN", sql),
+            "err_msg": "RENAMING columns",
+            "mode": "one_liner",
+        },
+        {
+            "code": "ALTER_COLUMN",
+            "fn": lambda sql, **kw: re.search(
+                "ALTER TABLE .* ALTER COLUMN .* TYPE", sql
+            ),
+            "err_msg": (
+                "ALTERING columns (Could be backward compatible. "
+                "You may ignore this migration.)"
+            ),
+            "mode": "one_liner",
+        },
+    ]
+
+    migration_tests = []
+
+    def __init__(self, exclude_migration_tests):
+        self.exclude_migration_tests = exclude_migration_tests or []
+        self.errors = []
+        self.ignored = []
+        self.migration_tests = update_migration_tests(
+            self.base_migration_tests, self.migration_tests
+        )
+
+    def analyse(self, sql_statements):
+        for statement in sql_statements:
+            for test in self.one_line_migration_tests:
+                self._test_sql(test, sql=statement)
+
+        for test in self.transaction_migration_tests:
+            self._test_sql(test, sql=sql_statements)
+
+    @property
+    def one_line_migration_tests(self):
+        return [test for test in self.migration_tests if test["mode"] == "one_liner"]
+
+    @property
+    def transaction_migration_tests(self):
+        return [test for test in self.migration_tests if test["mode"] == "transaction"]
+
+    def _test_sql(self, test, sql):
+        if test["fn"](sql, errors=self.errors):
+            if test["code"] in self.exclude_migration_tests:
+                logger.debug("Testing %s -- IGNORED", sql)
+                err = build_error_dict(migration_test=test, sql_statement=sql)
+                self.ignored.append(err)
+            else:
+                logger.debug("Testing %s -- ERROR", sql)
+                err = build_error_dict(migration_test=test, sql_statement=sql)
+                self.errors.append(err)
+        else:
+            logger.debug("Testing %s -- PASSED", sql)