Database¶

`kwai_core.db` ¶

Package for all database related modules.

ORM (Object-relational mapping) software (like SQLAlchemy) is not used. Instead, the repository pattern is used. A repository is responsible for saving, creating, querying and deleting entities. sql-smith is used to build queries.

The [DatabaseQuery][kwai.kwai_core.db.database_query.DatabaseQuery] class can be used to implement the Query interface.

`kwai_core.db.database` ¶

Module for database classes/functions.

`Database` ¶

Class for communicating with a database.

Attributes:

Name	Type	Description
`_connection`	`Connection \| None`	A connection
`_settings`	`DatabaseSettings`	The settings for this database connection.

`settings` `property` ¶

Return the database settings.

This property is immutable: the returned value is a copy of the current settings.

`begin()` `async` ¶

Start a transaction.

`check_connection()` `async` ¶

Check if the connection is set, if not it will try to connect.

`close()` `async` ¶

Close the connection.

`commit()` `async` ¶

Commit all changes.

`create_query_factory()` `classmethod` ¶

Return a query factory for the current database engine.

The query factory is used to start creating a SELECT, INSERT, UPDATE or DELETE query.

Returns:

Type	Description
`QueryFactory`	The query factory from sql-smith. Currently, it returns a query factory for the mysql engine. In the future it can provide other engines.

`delete(id_, table_name, id_column='id')` `async` ¶

Delete a row from the table using the id field.

Parameters:

Name	Type	Description	Default
`id_`	`Any`	The id of the row to delete.	required
`table_name`	`str`	The name of the table.	required
`id_column`	`str`	The name of the id column (default is 'id')	`'id'`

Raises:

Type	Description
`QueryException`	Raised when the query results in an error.

`execute(query)` `async` ¶

Execute a query.

The last rowid from the cursor is returned when the query executed successfully. On insert, this can be used to determine the new id of a row.

Parameters:

Name	Type	Description	Default
`query`	`AbstractQuery`	The query to execute.	required

Returns:

Type	Description
`int`	When the query is an insert query, it will return the last rowid.
`None`	When there is no last rowid.

Raises:

Type	Description
`QueryException`	Raised when the query contains an error.

`fetch(query)` `async` ¶

Execute a query and yields each row.

Parameters:

Name	Type	Description	Default
`query`	`SelectQuery`	The query to execute.	required

Yields:

Type	Description
`Record`	A row is a dictionary using the column names as key and the column values as value.

Raises:

Type	Description
`QueryException`	Raised when the query contains an error.

`fetch_one(query)` `async` ¶

Execute a query and return the first row.

Parameters:

Name	Type	Description	Default
`query`	`SelectQuery`	The query to execute.	required

Returns:

Type	Description
`Record`	A row is a dictionary using the column names as key and the column values as value.
`None`	The query resulted in no rows found.

Raises:

Type	Description
`QueryException`	Raised when the query contains an error.

`insert(table_name, *table_data, id_column='id')` `async` ¶

Insert one or more instances of a dataclass into the given table.

Parameters:

Name	Type	Description	Default
`table_name`	`str`	The name of the table	required
`table_data`	`Any`	One or more instances of a dataclass containing the values	`()`
`id_column`	`str`	The name of the id column (default is 'id')	`'id'`

Returns:

Type	Description
`int`	The last inserted id. When multiple inserts are performed, this will be the id of the last executed insert.

Raises:

Type	Description
`QueryException`	Raised when the query contains an error.

`log_affected_rows(rowcount)` ¶

Log the number of affected rows of the last executed query.

Parameters:

Name	Type	Description	Default
`rowcount`	`int`	The number of affected rows.	required

`log_query(query)` ¶

Log a query.

Parameters:

Name	Type	Description	Default
`query`	`str`	The query to log.	required

`rollback()` `async` ¶

Rollback a transaction.

`setup()` `async` ¶

Set up the connection pool.

`update(id_, table_name, table_data, id_column='id')` `async` ¶

Update a dataclass in the given table.

Parameters:

Name	Type	Description	Default
`id_`	`Any`	The id of the data to update.	required
`table_name`	`str`	The name of the table.	required
`table_data`	`Any`	The dataclass containing the data.	required
`id_column`	`str`	The name of the id column (default is 'id').	`'id'`

Raises:

Type	Description
`QueryException`	Raised when the query contains an error.

Returns:

Type	Description
`int`	The number of rows affected.

`kwai_core.db.database_query` ¶

Module that implements a query for a database.

`DatabaseQuery` ¶

Bases: Query

Creates a query using a database.

`columns` `abstractmethod` `property` ¶

Returns the columns used in the query.

`count_column` `property` ¶

The column used to count records.

`count()` `async` ¶

Execute the query and counts the number of records.

The count_column is used as column for a distinct count.

`fetch(limit=None, offset=None)` ¶

Fetch all records from this query.

`fetch_one()` `async` ¶

Fetch only one record from this query.

`init()` `abstractmethod` ¶

Override this method to create the base query.

`kwai_core.db.exceptions` ¶

Module that defines all database related exceptions.

`DatabaseException` ¶

Bases: Exception

Raised when a database error occurred.

`QueryException` ¶

Bases: DatabaseException

Raised when the execution of a query failed.

`sql` `property` ¶

Return the sql statement of the query.

`kwai_core.db.table_row` ¶

Module that defines some dataclasses that can be used as data transfer objects.

`JoinedTableRow` `dataclass` ¶

A data transfer object for data from multiple tables.

Each field of the dataclass will represent a table. The name of the field will be used as prefix for creating an alias for each column of the associated table.

The derived class must be a dataclass.

Note

The derived class is also the ideal place to act as builder for an entity.

`get_aliases()` `classmethod` ¶

Return fields of all the TableRow dataclasses as aliases.

The name of the field will be used as prefix for the alias.

`map(row)` `classmethod` ¶

Map all fields of this dataclass to the TableRow dataclasses.

`TableRow` `dataclass` ¶

A data transfer object for a row of one table.

The derived class must be a dataclass.

Note

The derived class is also the ideal place to act as builder for an entity.

`column(column_name)` `classmethod` ¶

Return the column prefixed with the table name.

`field(column_name)` `classmethod` ¶

Call sql-smith field with the given column.

short-cut for: field(table.table_name + '.' + column_name)

`get_aliases(prefix=None)` `classmethod` ¶

Return aliases for all the fields of the dataclass.

`get_column_alias(name, prefix=None)` `classmethod` ¶

Return the alias for a column.

`map(row, prefix=None)` `classmethod` ¶

Map the data of a row to the dataclass.

A ValueError will be raised when a field contains data with the wrong type.

`search(column_name)` `classmethod` ¶

Call sql-smith search with the given column.

short-cut for: search(table.table_name + '.' + column_name)

`unwrap(val)` ¶

Assert when the value is None.

Database¶

kwai_core.db ¶

kwai_core.db.database ¶

Database ¶

settings property ¶

begin() async ¶

check_connection() async ¶

close() async ¶

commit() async ¶

create_query_factory() classmethod ¶

delete(id_, table_name, id_column='id') async ¶

execute(query) async ¶

fetch(query) async ¶

fetch_one(query) async ¶

insert(table_name, *table_data, id_column='id') async ¶

log_affected_rows(rowcount) ¶

log_query(query) ¶

rollback() async ¶

setup() async ¶

update(id_, table_name, table_data, id_column='id') async ¶

kwai_core.db.database_query ¶

DatabaseQuery ¶

columns abstractmethod property ¶

count_column property ¶

count() async ¶

fetch(limit=None, offset=None) ¶

fetch_one() async ¶

init() abstractmethod ¶

kwai_core.db.exceptions ¶

DatabaseException ¶

QueryException ¶

sql property ¶

kwai_core.db.table_row ¶

JoinedTableRow dataclass ¶

get_aliases() classmethod ¶

map(row) classmethod ¶

TableRow dataclass ¶

column(column_name) classmethod ¶

field(column_name) classmethod ¶

get_aliases(prefix=None) classmethod ¶

get_column_alias(name, prefix=None) classmethod ¶

map(row, prefix=None) classmethod ¶

search(column_name) classmethod ¶

unwrap(val) ¶

`kwai_core.db` ¶

`kwai_core.db.database` ¶

`Database` ¶

`settings` `property` ¶

`begin()` `async` ¶

`check_connection()` `async` ¶

`close()` `async` ¶

`commit()` `async` ¶

`create_query_factory()` `classmethod` ¶

`delete(id_, table_name, id_column='id')` `async` ¶

`execute(query)` `async` ¶

`fetch(query)` `async` ¶

`fetch_one(query)` `async` ¶

`insert(table_name, *table_data, id_column='id')` `async` ¶

`log_affected_rows(rowcount)` ¶

`log_query(query)` ¶

`rollback()` `async` ¶

`setup()` `async` ¶

`update(id_, table_name, table_data, id_column='id')` `async` ¶

`kwai_core.db.database_query` ¶

`DatabaseQuery` ¶

`columns` `abstractmethod` `property` ¶

`count_column` `property` ¶

`count()` `async` ¶

`fetch(limit=None, offset=None)` ¶

`fetch_one()` `async` ¶

`init()` `abstractmethod` ¶

`kwai_core.db.exceptions` ¶

`DatabaseException` ¶

`QueryException` ¶

`sql` `property` ¶

`kwai_core.db.table_row` ¶

`JoinedTableRow` `dataclass` ¶

`get_aliases()` `classmethod` ¶

`map(row)` `classmethod` ¶

`TableRow` `dataclass` ¶

`column(column_name)` `classmethod` ¶

`field(column_name)` `classmethod` ¶

`get_aliases(prefix=None)` `classmethod` ¶

`get_column_alias(name, prefix=None)` `classmethod` ¶

`map(row, prefix=None)` `classmethod` ¶

`search(column_name)` `classmethod` ¶

`unwrap(val)` ¶