8.2.2. Miscellaneous notes about GenroPy

Last page update: September 22, 2015

8.2.2.1. Mapping models the database structure

In GenroPy, the transition from model classes to the database is in this way:

  1. The code in file in <name of package> / models / <table_name>. py builds a bag in python which builds the structure of the table.
  2. The constructed bag is translated into python objects.
  3. Genro script gnrdbsetup <projectName> compares these objects with the database structure and performs any updates required.

8.2.2.2. Mixin classes at runtime

GenroPy’s application class builds mixin classes at runtime. The methods and resources (CSS, JS, and Python components) are aggregated at runtime according to specific rules that allow you to customize the behavior for a single install and maintain these customizations, with minimal impact, even for future updates.

When code changes are made the WSGI application restarts.

It can perform the mixin of the interface (webpages, components, CSS, JS, etc.) and for the database structure (models).

TODO: See the wiki site http://projects.softwell.it/ the page Customization for an explanation of the rules of mixin and customization of applications.

8.2.2.3. Additional data types, not in the TextMate bundle

Tipo DH:
TimeStamp

8.2.2.4. GnrApp

The code to create an instance is as follows:

#!python
from gnr.app.gnrapp import GnrApp
instance = GnrApp('my_project')

  1. GnrApp.__init__ loads the configuration of the instance from instanceconfig.xml.

  2. GnrApp.init running:
    • the hook onIniting
    • creates necessary objects from packages
    • the hook onInited

8.2.2.5. GnrPackage

The file main.py of a package, you define class package and table. The methods of these classes are available at the respective web pages as self.package.name_of_method and as self.db.table('table name').name_of_method.

8.2.2.6. Page

Page objects can access the various application components using Genro instance variables:

  • self.package
  • self.db
  • self.application (es. self.application.config)
  • self.site (es. self.site.config)

8.2.2.7. Table Objects

The table objects are accessible from pages self.db.table('package.table'). The method query `` returns an object of type table. This object representing a table from the db may be configured according to the specified parameters.  The query on the db is not performed, until a further method is called. The methods that can be used include ``selection and variants of the fetch method to return data as list, dictionary, iterator or bag.

Example:

#!python

db = ...
tbl = db.table('common')
qry = tbl.query(...)
sel = qry.selection()

# edit records in memory, even adding new fields (eg for calculated fields to send to client)
sel.apply(lambda r: dict(area=r.base*r.height))

sel.output(format)

The selections support various formats:

  • bag: genro Bag (refer to gnr.core.gnrbag)
  • json: JSON serialization format

more: for other formats, see the methods with the prefix out_ object selection

The selections have methods to make totals or statistical analysis (averages, sums, etc..) aggregated into various fields. See the methods analyze or totalize.

NOTE: selections are implemented in terms of bags (not database) and can also be used with data sources from different db.

See also gnr.gnrsql.gnrsqldata for information on selection/query/record.

8.2.2.8. Useful Tools

BonjourFoxy: Firefox plugin to see the websites registered in the local network with Bonjour (useful in development)

Navicat: database editor with good support for Postgres

8.2.2.9. pycallgraph

Use the profiler python calls and shows how to graph using graphviz. To install it, use easy_install or pip:

sudo easy_install  -U -Z pycallgraph

8.2.2.10. Idea for a useful tool for development in Genro

Extracted relations (reading the Observer) between the interface and the datastore and display them in graphical form with graphviz.

NOTE: it has been implemented in gnrdbgraph.

8.2.2.11. Opensource policies of Softwell

  • The shell (packages in `` gnr .*``) will always remain open source.
  • In the future, Softwell could decide to continue the development of resources as closed source software.

8.2.2.12. Security in PDF files

To read local data or parameters of the URL may need a certificate to avoid the security alert (but maybe used by browsers and upload the PDF from the server, this is not needed).

8.2.2.13. Events and activities

Each interface element (widget or HTML tags) can attach javascript events using the syntax connect_<event_name>.

Example:

def divTest(self, parentContainer):
    cp = parentContainer.contentPane(...)
    cp.div(connect_onDoubleClick='JS code')

As a convention, the syntax connect_<event_name> is used for events or JavaScript dojo, while the syntax <event>_action is used for events and actions genropy.

8.2.2.14. Componenti per operare sul datastore

  • data(): stores a value in the datastore
  • dataFormula(): Calculate a cell of the datastore from other values (like a spreadsheet)
  • dataController(): Running JS code, linking it to an event in the datastore (through a resolver).

Parameters of dataController or dataFormula become delcarations of local variables used in the formula or the same JS.

8.2.2.15. Remote Operation

  • dataRecord() - TODO: to be explored - I question the need to store a database record in the datastore

  • dataRemote(): Set a resolver in the datastore. Access to this item in the datastore will be called Python code (defined in a function with the prefix rpc_ ) will return a bag.

  • dataRpc(): as above, dataRpc is the function of low-level underlying the previous functionality. It can be used to make calls to python code (via triggering resolver as parameters).

    It is possible to specify js code to call before the call(with the parameter onCalling='codice JS') or with the results received from the server (onresult='codice JS').

    The parameters of these functions that do not begin with an underscore “_” are passed to the server and are available to Python code called.

    The entry point into the web page called by these functions have the prefix rpc_.

    NOTE: You can use page.externalUrl(...) to get the URL of an RPC call (useful for passing URLs loading / saving XML to PDF document in the project myproject).

Functions can return:

  • a bag
  • a tuple (bag, dictionary) – dictionary contains the attributes / metadata bag, visible in the explorer of the datastore by clicking while holding down SHIFT

There is also an API to make changes to the datastore in RPCs.

8.2.2.16. Triggers

8.2.2.16.1. Triggers defined on a page

It is possible to define methods at the python-level of a web page that are called when the records in a given table are loaded or saved. The names of methods should follow this syntax:

on<Operation>
on<Operation>_<name_of_package>_<name_of_table>

Possible *Operation*s are: Loading, Saving or Saved.

This is implemented at rpc/web layer.

8.2.2.16.2. Triggers on a table

At the table level, events are similarly available Inserting/Inserted, Updating/Updated e Deleting/Deleted.

NOTE: you can specify whether the database should delete multiple records using a single SQL statement or individual statements for each record. There are different triggers for the two cases.