A Plomino application is supported by one or more Plomino databases.
The Plomino database is the Plone object which contains the application data (i.e. the Documents), and its structure (i.e. the Design).
The design of a Plomino application consists of the set of Forms and Views provided in the Plomino database.
The design defines the structure of the application, and it is created by the application designer. It differs from the documents, which are the application data, created by the users.
A :dfn:`form` allows users to view and/or to edit information.
A form usually contains some fields of various types (text, date, rich text, checkbox, attached files, etc.).
The application designer designs the layout he needs for the form, and inserts the fields wherever he wants.
A form can also contain some action buttons to trigger specific processing.
Forms are not always used to create or view documents — sometimes they are used to provide specific features (see Search forms, and Page forms).
The application designer can create specific forms dedicated to perform searches. These forms are not used to create documents, but to input the search criteria.
It allows the designer to provide more specific and more business-oriented search features than the global Plone search.
The application designer can create page forms to build custom navigation menus, generate reports, provide portlet content, etc.
A :dfn:`document` is a set of data. Data can be submitted by a user using a given :term:`form`.
Note
a document can be created using one form and then viewed or edited using a different form. The presentation of the document is determined by the form, which renders the data items found on the document. The fields on the form need not correspond one to one with the data items stored on the document: there may be more fields, or fewer fields, or the type of field may be different. Care should be taken to maintain consistency: make sure that the form matches the document.
This mechanism allows the document rendering and the displayed action buttons to change according to different parameters (user access rights, current document state, field values, etc.).
A :dfn:`view` defines a collection of documents.
A view has a selection formula which filters the documents that the application designer wants to be displayed in the view.
A view contains columns. :term:`Column` contents is computed from data stored in the documents.
A Plomino view is like a canned search. Views are built up incrementally,
and not assembled dynamically as would be the case for a catalog query.
Every time a document is saved, view formulas are evaluated, and if any of
them return True, the document is included in the view.
This has two implications:
- While it is cheap to keep the view up to date incrementally, it can be expensive to rebuild views from scratch, as this involves evaluating view formulas over all documents in the database.
- A document needs to be saved in order for its state to be reflected in views.
I.e. a simple
setItemis not enough.
Views store columns as catalog metadata. This effectively doubles the storage required for any field when it is added as a view column. It trades space for speed: the last-saved value of an expensive computed field can be obtained from the view column without having to execute the field formula again (but watch out for stale values, if the state or context of the document has changed since the last save).
Views can contain columns. The column values are stored and displayed (unless hidden) for every record that forms part of the view. A :dfn:`column` may refer to a form field, in which case that field will be used to render the record value, or it may specify a column formula, which need not correspond to one or any field.
Numerical columns can be added up to display column totals (the total for all the records in the view). If the column refers to a field, that field will also be used to render the total.
If desired, column totals can be dynamically computed in the browser per view batch. In order to enable this, include the following snippet in the View's :guilabel:`Dynamic Table Parameters`:
'fnFooterCallback': generateTableFooter,