_dbi_base - Private base module for all database interfaces
- Purpose:
This module contains the library's base database methods and attribute accessors, which are designed to be specialised by the database-specific modules and classes.
- Platform:
Linux/Windows | Python 3.10+
- Developer:
J Berendt
- Email:
- Comments:
This module contains only methods which can safely be inherited and used by any of its subclasses.
In other words, this module should not contain any import statement, or uses of these imports, which if used in a database-specific module will cause a crash due to a missing library.
Any database-specific functionality must be contained in that module.
- Example:
For class-specific usage examples, please refer to the docstring for the following classes:
- exception _dbi_base.SecurityWarning[source]
Bases:
Warning
Security warning stub-class.
- __cause__
exception cause
- __context__
exception context
- __delattr__(name, /)
Implement delattr(self, name).
- __getattribute__(name, /)
Return getattr(self, name).
- __init__(*args, **kwargs)
- __new__(**kwargs)
- __reduce__()
Helper for pickle.
- __repr__()
Return repr(self).
- __setattr__(name, value, /)
Implement setattr(self, name, value).
- __setstate__()
- __str__()
Return str(self).
- __suppress_context__
- __traceback__
- add_note()
Exception.add_note(note) -- add a note to the exception
- args
- with_traceback()
Exception.with_traceback(tb) -- set self.__traceback__ to tb and return self.
- class _dbi_base._DBIBase(connstr: str)[source]
Bases:
object
This class holds the methods and properties which are used across all databases. Each of the database-specific constructors inherits this class for its members.
Note
This class is not designed to be interacted with directly.
Rather, please use the
database.DBInterface
class instead, as the proper interface class has an automatic switch for database interfaces, based on thesqlalchemy.Engine
object which is created from the connection string.- Parameters:
connstr (str) -- The database-specific SQLAlchemy connection string.
- Example Use:
This low-level generalised class is designed to be inherited by the calling/wrapping class as:
>>> from dblib.database import DBInterface class MyDB(DBInterface): def __init__(self, connstr: str): super().__init__(connstr=('mysql+mysqlconnector://' '<user>:<pwd>@<host>:<port>/' '<db_name>'))
- _PREFIX = '\n[DatabaseError]:'
- _create_engine() sqlalchemy.engine.base.Engine [source]
Create a database engine using the provided environment.
- Returns:
A sqlalchemy database engine object.
- Return type:
sqlalchemy.engine.base.Engine
- static _is_dangerous(stmt: str) bool [source]
Perform a dirty security check for injection attempts.
- Parameters:
stmt (str) -- SQL statement to be potentially executed.
- Raises:
SecurityWarning -- If there are multiple semi-colons (
;
) in the statement, or any comment delimiters (--
).- Returns:
False if the checks pass.
- Return type:
bool
- _report_sa_error(msg: str, error: sqlalchemy.exc.SQLAlchemyError)[source]
Report SQLAlchemy error to the terminal.
- Parameters:
msg (str) -- Additional error to be displayed. This message will be automatically prefixed with '[DatabaseError]: '
error (sqlalchemy.exc.SQLAlchemyError) -- Caught error object from the try/except block.
- static _result_to_df__cursor(result: sqlalchemy.engine.cursor.CursorResult) DataFrame [source]
Convert a
CursorResult
object to a DataFrame.If the cursor did not return results, an empty DataFrame containing the column names only, is returned.
- Parameters:
result (sqlalchemy.engine.cursor.CursorResult) -- Object to be converted.
- Returns:
A
pandas.DataFrame
object containing the cursor's data.- Return type:
pd.DataFrame
- static _result_to_df__stored(result: object) DataFrame [source]
Convert a
MySQLCursor.stored_results
object to a DataFrame.- Parameters:
result (object) -- The
cursor.stored_results()
object fromcall. (a sqlalchemy or mysql.connector procedure)
- Returns:
A DataFrame containing the results from the procedure call.
- Return type:
pd.DataFrame
- property engine
Accessor to the
sqlalchemy.engine.base.Engine
object.
- execute_query(stmt: str, params: dict = None, raw: bool = True) list | DataFrame | None [source]
Execute a query statement.
Important
The following are not allowed to be executed by this method:
Statements containing multiple semi-colons (
;
).Statements containing a comment delimiter (
--
).
If found, a
SecurityWarning
will be raised by the_is_dangerous()
method.- Parameters:
stmt (str) -- Statement to be executed. The parameter bindings are to be written in colon format.
params (dict, optional) -- Parameter key/value bindings as a dictionary, if applicable. Defaults to None.
raw (bool, optional) -- Return the data in 'raw' (tuple) format rather than as a formatted DataFrame. Defaults to True for efficiency.
If the query did not return results and the
raw
argument is False, an empty DataFrame containing the column names only, is returned.Note
In the SQL query, the bind parameters are specified by name, using the format
:bind_name
. Theparams
dictionary argument must contain the associated parameter name/value bindings.Warning
Generally, whatever statement is passed into this method will be executed, and may have destructive implications.
This method contains a
commit
call.
If a statement is passed into this method, and the user has the appropriate permissions - the change will be committed.
... HC SVNT DRACONES.
- Returns:
If the
raw
parameter is True, a list of tuples containing values is returned. Otherwise, apandas.DataFrame
object containing the returned data is returned.If this method is called with a script which does not return results, for example a CREATE script, None is returned; regardless of the value passed to the
raw
parameter.- Return type:
list | pd.DataFrame | None