The files that must be placed in init_xml are the ones that relate to the
workflow definition, data to load at the installation of the software and
the data for the demonstrations.
XML Files
+++++++++
XML files located in the module directory are used to modify the structure of
the database. They are used for many purposes, among which we can cite :
* initialization and demonstration data declaration,
* views declaration,
* reports declaration,
* wizards declaration,
* workflows declaration.
General structure of OpenERP XML files is more detailed in the
:ref:`xml-serialization` section. Look here if you are interested in learning
more about *initialization* and *demonstration data declaration* XML files. The
following section are only related to XML specific to *actions, menu entries,
reports, wizards* and *workflows* declaration.
Objects
+++++++
All OpenERP resources are objects: menus, actions, reports, invoices, partners, ... OpenERP is based on an object relational mapping of a database to control the information. Object names are hierarchical, as in the following examples:
* account.transfer : a money transfer
* account.invoice : an invoice
* account.invoice.line : an invoice line
Generally, the first word is the name of the module: account, stock, sale.
* The fields login, password, etc are straightforward.
* The ref attribute allows to fill relations between the records :
..code-block:: xml
<field name="company_id" ref="main_company"/>
The field **company_id** is a many-to-one relation from the user object to the company object, and **main_company** is the id of to associate.
* The **eval** attribute allows to put some python code in the xml: here the groups_id field is a many2many. For such a field, "[(6,0,[group_admin])]" means : Remove all the groups associated with the current user and use the list [group_admin] as the new associated groups (and group_admin is the id of another record).
* The **search** attribute allows to find the record to associate when you do not know its xml id. You can thus specify a search criteria to find the wanted record. The criteria is a list of tuples of the same form than for the predefined search method. If there are several results, an arbitrary one will be chosen (the first one):
This is a classical example of the use of **search** in demo data: here we do not really care about which partner we want to use for the test, so we give an empty list. Notice the **model** attribute is currently mandatory.
Record Tag
//////////
**Description**
The addition of new data is made with the record tag. This one takes a mandatory attribute : model. Model is the object name where the insertion has to be done. The tag record can also take an optional attribute: id. If this attribute is given, a variable of this name can be used later on, in the same file, to make reference to the newly created resource ID.
A record tag may contain field tags. They indicate the record's fields value. If a field is not specified the default value will be used.
Views are a way to represent the objects on the client side. They indicate to the client how to lay out the data coming from the objects on the screen.
There are two types of views:
* form views
* tree views
Lists are simply a particular case of tree views.
A same object may have several views: the first defined view of a kind (*tree, form*, ...) will be used as the default view for this kind. That way you can have a default tree view (that will act as the view of a one2many) and a specialized view with more or less information that will appear when one double-clicks on a menu item. For example, the products have several views according to the product variants.
Views are described in XML.
If no view has been defined for an object, the object is able to generate a view to represent itself. This can limit the developer's work but results in less ergonomic views.
Usage example
/////////////
When you open an invoice, here is the chain of operations followed by the client:
* An action asks to open the invoice (it gives the object's data (account.invoice), the view, the domain (e.g. only unpaid invoices) ).
* The client asks (with XML-RPC) to the server what views are defined for the invoice object and what are the data it must show.
* The client displays the form according to the view
..figure:: images/arch_view_use.png
:scale:50
:align:center
To develop new objects
//////////////////////
The design of new objects is restricted to the minimum: create the objects and optionally create the views to represent them. The PostgreSQL tables do not have to be written by hand because the objects are able to automatically create them (or adapt them in case they already exist).
Reports
"""""""
OpenERP uses a flexible and powerful reporting system. Reports are generated either in PDF or in HTML. Reports are designed on the principle of separation between the data layer and the presentation layer.
Reports are described more in details in the `Reporting <http://openobject.com/wiki/index.php/Developers:Developper%27s_Book/Reports>`_ chapter.
Workflow
""""""""
The objects and the views allow you to define new forms very simply, lists/trees and interactions between them. But that is not enough, you must define the dynamics of these objects.
A few examples:
* a confirmed sale order must generate an invoice, according to certain conditions
* a paid invoice must, only under certain conditions, start the shipping order
The workflows describe these interactions with graphs. One or several workflows may be associated to the objects. Workflows are not mandatory; some objects don't have workflows.
Below is an example workflow used for sale orders. It must generate invoices and shipments according to certain conditions.
..figure:: images/arch_workflow_sale.png
:scale:85
:align:center
In this graph, the nodes represent the actions to be done: