mahara-contributors team mailing list archive

[Aaron Wells <1537861@xxxxxxxxxxxxxxxxxx>]

Hi Matt,

In belated response to your question about why there are so many tables
to track view layouts, we do have a couple that could be consider
unnecessary if everything was redesigned, but on the whole it's actually
a fairly logical mapping of the flexibility of our page layout engine
into a relational database:

1. view_layout_columns: A "column layout", i.e. a number of columns, and
what page-width each one has. (1 column, 2 columns 50/50, 2 columns
67/33, etc). These are hard-coded.

2. view_layout: Each record is a view layout (i.e. a combination of rows
and columns). This includes the 34 hard-coded view layouts that ship
with Mahara, and any custom layouts users have produced (if my math is
correct, with 1 to 5 rows and 12 different column layouts, there are
12^5 + 12^4 + ... + 12 = 271,452 possible layouts)

3. view_layout_rows_columns: Each record represents one row in a view
layout. It indicates which row number it is, and which of the column
layouts it uses.

4. usr_custom_layout: Each record is one custom layout generated by a
user (or group or institution). This table is used to "bookmark"
previously used custom layouts for the user.

If I was rewriting it from scratch, I would probably rename some of the
tables to make things clearer. The relationship between view_layout,
view_layout_columns, and view_layout_rows_columns is not really made
clear by the table names or their column names.

Also, since we've currently hard-coded the views to a maximum of 5 rows,
it could also make sense to eliminate the view_layout_rows_columns
table, and instead give view_layout 5 fields called "row1layout",
"row2layout", etc. And from there, you could also eliminate the
"view_layout_columns" table, which describes the column layout with
strings like "33,33,33", and just move those strings directly into
view_layout.row1layout, view_layout.row2layout, etc.

But, at this point it's probably not worth all the refactoring that
would require.

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https://bugs.launchpad.net/bugs/1537861

Title:
  View layout becomes corrupted when changed

Status in Mahara:
  Confirmed
Status in Mahara 15.04 series:
  Triaged
Status in Mahara 15.10 series:
  Triaged

Bug description:
  Version: Mahara 15.04.5 (only encountered on this version, after
  upgrading from 15.04.4)

  We have had 2 users (out of over a thousand) have this problem so far,
  and I've been unable reproduce it or trace a specific cause but we do
  know the order of events and the outcome:

  They copy a page from another user
  Change content or add some new content
  Attempt to change the layout (say from 3 columns to 2 columns)

  Something goes wrong while the layout is being changed and the data in
  the table view_rows_columns no longer matches what's in the view
  table, and the page won't load anymore.

  As more users encounter this problem (and I'm assuming they will) I
  will update this report.

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