[daisy] Dereference operator for query language

[Scott Warren]

Hello,

I have written a UserHasRole predicate for Daisy 1.5 as we had discussed
before. This is useful for ACL where a Document has a Field that matches up
with the Roles that a user may have. Example

User A -> Role1, Role2, Role3
User B -> RoleA, RoleB, *Role3

Document A -> $RoleField  = Role5, RoleT, RoleG
Document B -> $RoleField  = *Role3, RoleT, RoleG

With the above configuration UserHasRole($RoleField) would be true for User
B but not User A because User B has the role Role3 and the field has the
value Role3

I made it like the InCollection predicate and allow multiple fields eg
UserHasRole($Field1, $Field2, $Field3)

I know this is for 1.5 is this useful and if so how can I get you a patch?

Regards
 
 
Scott Warren


> -----Original Message-----
> From: daisy-bounces at lists.cocoondev.org [mailto:daisy-
> bounces at lists.cocoondev.org] On Behalf Of Bruno Dumon
> Sent: Saturday, 27 January 2007 3:11 AM
> To: Daisy: open source CMS - general mailinglist
> Subject: [daisy] Dereference operator for query language
> 
> Hi,
> 
> I've been working on a new construct for the query language called the
> "dereference operator". It allows queries to traverse link fields in
> order to test on the values in the linked-to documents.
> 
> For example:
> 
> select $LinkField=>name where $LinkField=>name like 'foo%'
> 
> The "=>" is used as notation for the link dereference operator (it is
> not "->" because dash is a valid character in identifiers in Daisy).
> 
> So this query will return all documents that have a link field
> "$LinkField" which points to documents of which the name start with
> "foo". Doing a query like this was previously impossible.
> 
> The link dereferencing can work as many levels of links deep as you
> like, so it's possible to do things like:
> 
> ... where $LinkField=>$OtherLinkField=>$YetAnotherLinkField like 'foo%'
> 
> It can basically be used everywhere where you can put a "value
> expression", thus also in the order by clause, as argument to functions,
> etc. It also works in the stand-alone expressions as used in the ACL or
> the publisher.
> 
> Access control is also taken care of: if you try to dereference a link
> in the where clause, but you have no access to the document in the link,
> then the corresponding row will be removed from the result set (this is
> a special filtering performed by Daisy after executing the query on the
> SQL engine). In the select or order-by parts, a non-traversable link
> will simply give a "null" value.
> 
> I've developed this functionality on a separate branch (BRANCH_DEREF),
> which I'll merge into trunk soon.
> 
> Thoughts, remarks, questions welcome.
> 
> --
> Bruno Dumon                             http://outerthought.org/
> Outerthought - Open Source, Java & XML Competence Support Center
> bruno at outerthought.org                          bruno at apache.org
> 
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