Roundup Tracker - Issues

Issue 2550923

classification
Title: Create new Computed property type
Type: rfe Severity: normal
Components: Versions:
process
Status: new Resolution:
Dependencies: Superseder:
Assigned To: Nosy List: antmail, rouilj, schlatterbeck
Priority: normal Keywords: Effort-High, GSOC

Created on 2016-07-07 02:04 by rouilj, last changed 2016-07-15 11:13 by antmail.

Messages
msg5773 Author: [hidden] (rouilj) Date: 2016-07-07 02:04
At: https://sourceforge.net/p/roundup/mailman/message/34268641/

is a discussion of computed properties for a class.

Use case: suppose you wanted to have a count of the number of messages
in an issue.

You can add a msg_count:

 issue = IssueClass(db,'issue',
   ....
   msg_count = Number()

to the issue, but then you need an auditor to keep the count up to
date, and it has to run on every msg update even if nobody ever asks
for the msg_count.

Suppose you could instead add:

   msg_count = Computed("countIssueMessages")

When somebody does a db.issue.get(id, 'msg_count') the function:

  countIssueMessages(InstanceOfIssueClass, db)

is invoked. Then in schema.py (or lib/) I define:

Class Computed:

 def countIssueMessages(Myissue, db):
        return Myissue['msgs'].count()

Use Case: this could be used for getting the user phone number from an
external address book by changing the user schema to read:

   user = Class(db, "user",
                ...
                phone=Computed("getPhoneFromLdap")

then:

  def getPhoneFromLdap(Myuser, db):
         return lookupPhoneGivenUser(Myuser['username'])

So this way there is no need to "sync" a bunch of data from an external
source into roundup.

Design etc. TBD. But I wanted to get this in the tracker as it seems it
may be a good summer of code idea for the future.

Note that there is no way to set the properties, they are strictly
read only at this time.
msg5858 Author: [hidden] (antmail) Date: 2016-07-15 11:13
> At: https://sourceforge.net/p/roundup/mailman/message/34268641/

> is a discussion of computed properties for a class.

I  think  this  is very interesting issue. I think we must discuss a
design and future direction of roundup-tracker.

There are my raw thoughts.
 I  think that a ReadOnly  properties is more suitable to roundup-tracker
 conception  than  Computed. Firstly it can be typified and then
 used in template as usual.
 The example of external address book will look like:

user = Class(db, "user",
                ...
                phone=ROString("getPhoneFromLdap")
                ...
then:

  def getPhoneFromLdap(MyUser):
         return lookupPhoneGivenUser(Myuser['username'])
History
Date User Action Args
2016-07-15 11:13:47antmailsetnosy: + antmail
messages: + msg5858
2016-07-12 15:34:14schlatterbecksetnosy: + schlatterbeck
2016-07-07 02:04:39rouiljcreate