There's virtually no reason in normal applications against a fixed schema to tear down mappings and table metadata between tests. Unit tests in an outside world application would normally be against a schema that's an integral part of the application, and doesn't change with regards to classes. Like MetaData.remove(), there's almost no real world use case for clear_mappers() except that of the SQLAlchemy unit tests themselves, or tests of other ORM-integration layers like Elixir, which are testing the ORM itself with various kinds of mappings against the same set of classes. The use case for removing individual mappers is not supported as there is no support for doing all the reverse bookkeeping of removing relationships(), backrefs, and inheritance structures, and there's really no need for such a feature. If you want to remove mappings, you can call clear_mappers(). In reality the MetaData.remove() method is mostly useless, except that a create_all() will no longer hit that Table, foreign key references will no longer find it, and you can replace it with a new Table object of the same name, but again nothing to do with the ORM and nothing to do with the state of that removed Table, which still points to that MetaData and will otherwise function normally. Removing a Table from a particular MetaData has almost no effect as all the ORM mappings still point to it. The Table and Metadata objects are part of Core and know absolutely nothing about the ORM or mappings.
OK I think you're mixing concepts up here, a backref is an ORM concept. > name on a relationship already existing. > tearDown ans setUp in between), I still get an error about a backref > generate the same tables in two separate test methods (with a call to > This time I am also removing the tables from the metadata, but if i > I was wrong, the method emptied the database, but I was checking the Is there a way to achieve this or am i missing something?
Delete sqlite database how to#
Know how to reinitialize it with the classes/tables hard coded in the I have also considered creating new metadata in setUp, but i would not The first i just want to remove the records (or regenerate the tablesįrom the existing metadata), while the others i want to remove Others are generated on the flight (from the class definitions).
Some tables (with class definitions) are defined in modules, while The DropEverything function) and all tables except from the excludesįrom the metadata (with metadata.remove(table) ). With tools.drop_tables removing all tables from the database (using Tools.drop_tables(tadata, engine, excludes) That somehow the metadata retains the class definitions.
In separate runs the error does not occur and from that i conclude TearDown ans setUp in between), I still get an error about a backref Generate the same tables in two separate test methods (with a call to This time I am also removing the tables from the metadata, but if i Now, COMPANY table does not have any record as all the records have been deleted by DELETE statement.I was wrong, the method emptied the database, but I was checking the If you want to DELETE all the records from COMPANY table, you do not need to use WHERE clause with DELETE query, which will be as follows − Now COMPANY table will have the following records. Sqlite> DELETE FROM COMPANY WHERE ID = 7 ExampleĬonsider COMPANY table with the following records.įollowing is an example, which will DELETE a customer whose ID is 7. You can combine N number of conditions using AND or OR operators. Syntaxįollowing is the basic syntax of DELETE query with WHERE clause. You can use WHERE clause with DELETE query to delete the selected rows, otherwise all the records would be deleted. SQLite DELETE Query is used to delete the existing records from a table.