connection.py
This module contains the Connection class that manages the connection to the database, and
the conn
function that provides access to a persistent connection in datajoint.
Connection
¶
A dj.Connection object manages a connection to a database server. It also catalogues modules, schemas, tables, and their dependencies (foreign keys).
Most of the parameters below should be set in the local configuration file.
:param host: host name, may include port number as hostname:port, in which case it overrides the value in port :param user: user name :param password: password :param port: port number :param init_fun: connection initialization function (SQL) :param use_tls: TLS encryption option
Source code in datajoint/connection.py
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cancel_transaction()
¶
Cancels the current transaction and rolls back all changes made during the transaction.
Source code in datajoint/connection.py
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commit_transaction()
¶
Commit all changes made during the transaction and close it.
Source code in datajoint/connection.py
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connect()
¶
Connect to the database server.
Source code in datajoint/connection.py
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get_user()
¶
:return: the user name and host name provided by the client to the server.
Source code in datajoint/connection.py
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in_transaction()
property
¶
:return: True if there is an open transaction.
Source code in datajoint/connection.py
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is_connected()
property
¶
Return true if the object is connected to the database server.
Source code in datajoint/connection.py
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ping()
¶
Ping the connection or raises an exception if the connection is closed.
Source code in datajoint/connection.py
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purge_query_cache()
¶
Purges all query cache.
Source code in datajoint/connection.py
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query(query, args=(), *, as_dict=False, suppress_warnings=True, reconnect=None)
¶
Execute the specified query and return the tuple generator (cursor).
:param query: SQL query :param args: additional arguments for the client.cursor :param as_dict: If as_dict is set to True, the returned cursor objects returns query results as dictionary. :param suppress_warnings: If True, suppress all warnings arising from underlying query library :param reconnect: when None, get from config, when True, attempt to reconnect if disconnected
Source code in datajoint/connection.py
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set_query_cache(query_cache=None)
¶
When query_cache is not None, the connection switches into the query caching mode, which entails: 1. Only SELECT queries are allowed. 2. The results of queries are cached under the path indicated by dj.config['query_cache'] 3. query_cache is a string that differentiates different cache states.
:param query_cache: a string to initialize the hash for query results
Source code in datajoint/connection.py
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start_transaction()
¶
Starts a transaction error.
Source code in datajoint/connection.py
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transaction()
property
¶
Context manager for transactions. Opens an transaction and closes it after the with statement. If an error is caught during the transaction, the commits are automatically rolled back. All errors are raised again.
Example:
import datajoint as dj with dj.conn().transaction as conn: # transaction is open here
Source code in datajoint/connection.py
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EmulatedCursor
¶
acts like a cursor
Source code in datajoint/connection.py
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conn(host=None, user=None, password=None, *, init_fun=None, reset=False, use_tls=None)
¶
Returns a persistent connection object to be shared by multiple modules. If the connection is not yet established or reset=True, a new connection is set up. If connection information is not provided, it is taken from config which takes the information from dj_local_conf.json. If the password is not specified in that file datajoint prompts for the password.
:param host: hostname :param user: mysql user :param password: mysql password :param init_fun: initialization function :param reset: whether the connection should be reset or not :param use_tls: TLS encryption option. Valid options are: True (required), False (required no TLS), None (TLS prefered, default), dict (Manually specify values per https://dev.mysql.com/doc/refman/5.7/en/connection-options.html#encrypted-connection-options).
Source code in datajoint/connection.py
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translate_query_error(client_error, query)
¶
Take client error and original query and return the corresponding DataJoint exception.
:param client_error: the exception raised by the client interface :param query: sql query with placeholders :return: an instance of the corresponding subclass of datajoint.errors.DataJointError
Source code in datajoint/connection.py
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