Archive Project

# Conflicts:
#	.gitignore

alembic_data/ops/delete_row.py

@@ -0,0 +1,54 @@
+from typing import Any, Mapping, List
+
+import sqlalchemy
+from alembic.autogenerate import renderers
+from alembic.autogenerate.api import AutogenContext
+from alembic.operations import Operations, MigrateOperation
+from sqlalchemy import and_
+
+__all__ = ["DeleteRowOp"]
+
+from sqlalchemy.sql.elements import ColumnClause
+
+
+@Operations.register_operation("delete_row")
+class DeleteRowOp(MigrateOperation):
+    """This `MigrationOperation` deletes a rows from a database table."""
+
+    def __init__(self, table_name: str, **kwargs: Mapping[str, Any]) -> None:
+        """Creates a new `DeleteRowOp`.
+
+        :param table_name: The name of the table to delete the row from.
+        :param kwargs: The values used to identify the exact row. Keys must correspond to column names in the table and
+                       values to their values.
+        """
+        self.table_name = table_name
+        self.values = kwargs
+
+    @classmethod
+    def delete_row(cls, operations: Operations, table_name: str, **kwargs: Mapping[str, Any]):
+        """Factory method for `DeleteRowOp`."""
+        op = DeleteRowOp(table_name, **kwargs)
+        return operations.invoke(op)
+
+    def reverse(self) -> MigrateOperation:
+        """Reverses the insert row operation by inserting the respective row."""
+        from .insert_row import InsertRowOp
+        return InsertRowOp(self.table_name, **self.values)
+
+
+@Operations.implementation_for(DeleteRowOp)
+def delete_row(operations, operation: DeleteRowOp) -> None:
+    columns: List[ColumnClause] = [sqlalchemy.column(key) for key in operation.values.keys()]
+    table = sqlalchemy.table(operation.table_name, *columns)
+    where_clauses = [table.columns[key] == value for (key, value) in operation.values.items()]
+    sql = table.delete().where(and_(*where_clauses))
+    operations.execute(sql)
+
+
+@renderers.dispatch_for(DeleteRowOp)
+def render_delete_row(autogen_context: AutogenContext, op: DeleteRowOp) -> str:
+    return "op.delete_row(%r, **%r)" % (
+        op.table_name,
+        op.values
+    )