added schemachecker validation function and error class

CveXplore/database/maintenance/DatabaseSchemaChecker.py

@@ -3,6 +3,7 @@
 import os
 
 from CveXplore.database.connection.mongo_db import MongoDBConnection
+from CveXplore.errors import DatabaseSchemaError
 
 runPath = os.path.dirname(os.path.realpath(__file__))
 
@@ -18,6 +19,33 @@ def __init__(self):
 
         self.logger = logging.getLogger("SchemaChecker")
 
+    def validate_schema(self):
+        if hasattr(self.dbh.connection, "store_schema"):
+            try:
+                if (
+                    not self.schema_version["version"]
+                    == list(self.dbh.connection.store_schema.find({}))[0]["version"]
+                ):
+                    if not self.schema_version["rebuild_needed"]:
+                        raise DatabaseSchemaError(
+                            "Database is not on the latest schema version; please update the database!"
+                        )
+                    else:
+                        raise DatabaseSchemaError(
+                            "Database schema is not up to date; please re-populate the database!"
+                        )
+                else:
+                    return True
+            except IndexError:
+                # something went wrong fetching the result from the database; assume re-populate is needed
+                raise DatabaseSchemaError(
+                    "Database schema is not up to date; please re-populate the database!"
+                )
+        else:
+            raise DatabaseSchemaError(
+                "Database schema is not up to date; please re-populate the database!"
+            )
+
     def create_indexes(self):
         # hack for db_updater.py to put this class in the posts variable and run the update method
         self.logger.info("Updating schema version")

CveXplore/errors/database.py

@@ -16,3 +16,7 @@ class DatabaseIllegalCollection(DatabaseException):
 
 class UpdateSourceNotFound(DatabaseException):
     pass
+
+
+class DatabaseSchemaError(DatabaseException):
+    pass