[ssplanner] Prevent execution of write queries involving computed relations
Previously, setting a computed relation upon entity creation or
modification (using the ORM or an RQL query) would usually fail with an
operational error in the backend ("no such table"). However, under some
mysterious circumstances (like passing a string as value in cw_set for a
computed relation), the RQL to SQL transformation would simply drop the
clause.
To prevent this to happen, we add a check for computed relation before
adding a relation to an execution plan. This check raises a QueryError.
It happens in several places:
* in querier.InsertPlan.add_relation_def() (called from several places
in ssplanner steps) for INSERT queries,
* in ssplanner.UpdateStep.execute() for SET queries and,
* in ssplanner.SSplanner.build_delete_plan() for DELETE queries.
Tests added to unittest_querier.py because unittest_sslplanner.py looked
inappropriate (it has only unit tests) and the former already had a
NonRegressionTC class.
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Refactoring the CSSs with UI properties
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Overview
=========
Managing styles progressively became difficult in CubicWeb. The
introduction of uiprops is an attempt to fix this problem.
The goal is to make it possible to use variables in our CSSs.
These variables are defined or computed in the uiprops.py python file
and inserted in the CSS using the Python string interpolation syntax.
A quick example, put in ``uiprops.py``::
defaultBgColor = '#eee'
and in your css::
body { background-color: %(defaultBgColor)s; }
The good practices are:
- define a variable in uiprops to avoid repetitions in the CSS
(colors, borders, fonts, etc.)
- define a variable in uiprops when you need to compute values
(compute a color palette, etc.)
The algorithm implemented in CubicWeb is the following:
- read uiprops file while walk up the chain of cube dependencies: if
cube myblog depends on cube comment, the variables defined in myblog
will have precedence over the ones in comment
- replace the %(varname)s in all the CSSs of all the cubes
Keep in mind that the browser will then interpret the CSSs and apply
the standard cascading mechanism.