mirror of
https://github.com/psycopg/psycopg2.git
synced 2024-09-21 11:18:49 +03:00
Completed documentation for the COPY-related methods.
This commit is contained in:
Daniele Varrazzo
Federico Di Gregorio
parent
d081d533b9
commit
ac6640fd9e
|
|
@ -339,42 +339,67 @@ The ``cursor`` class
|
|||
This method currently does nothing but it is safe to call it.
|
||||
|
||||
|
||||
.. method:: copy_from(file, table, sep='\\t', null='\\N', columns=None)
|
||||
|
||||
Read data *from* the file-like object :obj:`file` appending them to
|
||||
the table named :obj:`table`. :obj:`file` must have both ``read()``
|
||||
and ``readline()`` method. See :ref:`copy` for an overview. ::
|
||||
|
||||
>>> f = StringIO("42\tfoo\n74\tbar\n")
|
||||
>>> cur.copy_from(f, 'test', columns=('num', 'data'))
|
||||
|
||||
>>> cur.execute("select * from test where id > 5;")
|
||||
>>> cur.fetchall()
|
||||
[(7, 42, 'foo'), (8, 74, 'bar')]
|
||||
|
||||
The optional argument :obj:`sep` is the columns separator and
|
||||
:obj:`null` represents ``NULL`` values in the file.
|
||||
|
||||
The :obj:`columns` argument is a sequence of field names: if not
|
||||
``None`` only the specified fields will be included in the dump.
|
||||
|
||||
.. versionchanged:: 2.0.6
|
||||
added the :obj:`columns` parameter.
|
||||
|
||||
.. method:: copy_to(file, table, sep='\\t', null='\\N', columns=None)
|
||||
|
||||
Write the content of the table named :obj:`table` *to* the file-like object :obj:`file`. :obj:`file` must have a ``write()`` method. See
|
||||
:ref:`copy` for an overview. ::
|
||||
|
||||
>>> cur.copy_to(sys.stdout, 'test', sep="|")
|
||||
1|100|abc'def
|
||||
2|\N|dada
|
||||
|
||||
The optional argument :obj:`sep` is the columns separator and
|
||||
:obj:`null` represents ``NULL`` values in the file.
|
||||
|
||||
The :obj:`columns` argument is a sequence representing the fields
|
||||
where the read data will be entered. Its length and column type should
|
||||
match the content of the read file.
|
||||
|
||||
.. versionchanged:: 2.0.6
|
||||
added the :obj:`columns` parameter.
|
||||
|
||||
.. method:: copy_expert(sql, file [, size])
|
||||
|
||||
Submit a user-composed COPY statement.
|
||||
Submit a user-composed ``COPY`` statement. The method is useful to
|
||||
handle all the parameters that PostgreSQL makes available (see
|
||||
|COPY|__ command documentation).
|
||||
|
||||
>>> cur.copy_expert("COPY test TO STDOUT WITH CSV HEADER", sys.stdout)
|
||||
id,num,data
|
||||
1,100,abc'def
|
||||
2,,dada
|
||||
|
||||
:obj:`file` must be an open, readable file for ``COPY FROM`` or an
|
||||
open, writeable file for ``COPY TO``. The optional :obj:`size`
|
||||
argument, when specified for a ``COPY FROM`` statement, will be passed
|
||||
to file's read method to control the read buffer size.
|
||||
to file's read method to control the read buffer size.
|
||||
|
||||
.. todo::
|
||||
.. |COPY| replace:: ``COPY``
|
||||
.. __: http://www.postgresql.org/docs/8.4/static/sql-copy.html
|
||||
|
||||
I'm sure copy_expert can be described better!
|
||||
|
||||
.. method:: copy_from(file, table, sep='\t', null='\N', columns=None)
|
||||
|
||||
Read data *from* the file-like object :obj:`file` appending them to
|
||||
the table named :obj:`table`. See :ref:`copy`.
|
||||
|
||||
:obj:`file` must have both ``read()`` and ``readline()`` method.
|
||||
|
||||
The optional arguments: :obj:`sep` is the columns separator and
|
||||
:obj:`null` represents ``NULL`` values in the file.
|
||||
|
||||
.. todo:: columns argument in copy_from
|
||||
|
||||
.. method:: copy_to(file, table, sep='\t', null='\N', columns=None)
|
||||
|
||||
Write the content of the table named :obj:`table` *to* the file-like
|
||||
object :obj:`file`. See :ref:`copy`.
|
||||
|
||||
:obj:`file` must have a ``write()`` method.
|
||||
|
||||
The optional arguments: :obj:`sep` is the columns separator and
|
||||
:obj:`null` represents ``NULL`` values in the file.
|
||||
|
||||
.. todo:: columns argument in copy_to
|
||||
.. versionadded:: 2.0.6
|
||||
|
||||
.. attribute:: row_factory
|
||||
|
||||
|
|
|
|||
|
|
@ -339,19 +339,26 @@ Using COPY TO and COPY FROM
|
|||
---------------------------
|
||||
|
||||
Psycopg :class:`cursor` objects provide an interface to the efficient
|
||||
PostgreSQL `COPY command`_ to move data from files to tables and back.
|
||||
PostgreSQL |COPY|__ command to move data from files to tables and back.
|
||||
The methods exposed are:
|
||||
|
||||
The :meth:`cursor.copy_to()` method writes the content of a table *to* a
|
||||
file-like object. The target file must have a ``write()`` method.
|
||||
:meth:`cursor.copy_to()`
|
||||
Writes the content of a table *to* a file-like object (``COPY table TO
|
||||
file`` syntax). The target file must have a ``write()`` method.
|
||||
|
||||
The :meth:`cursor.copy_from()` reads data *from* a file-like object appending
|
||||
them to a database table. The source file must have both ``read()`` and
|
||||
``readline()`` method.
|
||||
:meth:`cursor.copy_from()`
|
||||
Reads data *from* a file-like object appending them to a database table
|
||||
(``COPY table FROM file`` syntax). The source file must have both
|
||||
``read()`` and ``readline()`` method.
|
||||
|
||||
Both methods accept two optional arguments: ``sep`` (defaulting to a tab) is
|
||||
the columns separator and ``null`` (defaulting to ``\N``) represents ``NULL``
|
||||
values in the file.
|
||||
:meth:`cursor.copy_expert()`
|
||||
Allows to handle more specific cases and to use all the |COPY| features
|
||||
available in PostgreSQL.
|
||||
|
||||
.. _COPY command: http://www.postgresql.org/docs/8.4/static/sql-copy.html
|
||||
Please refer to the documentation of the single methods for details and
|
||||
examples.
|
||||
|
||||
.. |COPY| replace:: ``COPY``
|
||||
.. __: http://www.postgresql.org/docs/8.4/static/sql-copy.html
|
||||
|
||||
|
||||
|
|
|
|||
Loading…
Reference in New Issue
Block a user