1 .. _renamehowto:

     2 

     3 

     4 How to rename classes of existing objects ?

     5 ===========================================

     6 

     7 

     8 PyAMS provides `zodbupdate` script to update easily update the change in ZODB. Because, when you develop new features

     9 to PyAMS we sometimes have to rename or modify classes of already stored objects and if you do that you will never access

    10 yours objects

    11 

    12 

    13 **1) Include you package in the require resource for you webapp**

    14 

    15 

    16 .. code-block:: python

    17 

    18     requires = [

    19         'mypackage',

    20         ...

    21     ]

    22 

    23 **2) Add the Entry points**

    24 

    25 

    26 In the `setup.py` file add 'zodbupdate' params into entry_points where is store zodbupdate directives

    27 

    28 .. code-block:: python

    29 

    30       entry_points={

    31           'zodbupdate': [

    32               'renames = mypackage.generations:RENAMED_CLASSES'

    33           ]

    34       }

    35 

    36 

    37 

    38 **3) Create a module named** ``generation`` **with the migration directives**

    39 

    40 

    41 .. code-block:: python

    42 

    43     RENAMED_CLASSES = {

    44         'mypackage.mymodule MyOldClass': 'mypackage.mymodule MyNewClass'

    45     }

    46 

    47 

    48 **4) Run the commands** ``buildout`` .

    49 

    50 .. code-block:: console

    51 

    52     $ mypackage/bin/buildout

    53     $ webapp/bin/buildout

    54 

    55 

    56 The ``buildout`` command going to install correctly the package and add the new entry_points references in entry_points.txt

    57 

    58 **5)  Run the commands** ``zodbupdate``

    59 

    60 To finish run `zodbupdate` to apply the changes describe in `RENAMED_CLASSES`

    61 

    62 .. code-block:: console

    63 

    64     $   bin/zodbupdate --config etc/zodbupdate-zeo.conf

    65 

    66 

    67 Where `zodbupdate-zeo.conf` is the configuration file to access to the ZODB.