Is it possible to have OR conditions using named scope ?? For e.g. Gather users based on following or conditions. 1. active is one named scope which finds all users whose state is active 2. OR user id is in 1,2,3
This condition can be written in only one named scope as
named_scope :active_or_explicit, lambda{ |ids| { :conditions => ['state = ? OR id in (?)', 'active', [1,2,3]] } }
Is it possible to have two named scopes that can be joined using OR condition.
Please let me know your views...
Sandip Ransing wrote:
Is it possible to have OR conditions using named scope ?? For e.g. Gather users based on following or conditions. 1. active is one named scope which finds all users whose state is active 2. OR user id is in 1,2,3
This condition can be written in only one named scope as
named_scope :active_or_explicit, lambda{ |ids| { :conditions => ['state = ? OR id in (?)', 'active', [1,2,3]] } }
Is it possible to have two named scopes that can be joined using OR condition.
Goodness, I hope not. That would be a terrible misuse of named_scopes.
Please let me know your views...
Please see http://groups.google.com/group/rubyonrails-talk/msg/7789576953707b2e for some of my reasoning.
-- Sandip
--- www.funonrails.com
Best,
Marnen thx for reply !
Actually I wanted to add "OR" condition to acts_as_mappable finders,
So that result-set will contain my own preferences too...but now it looks like
for this purpose i may either need to mess up with library of
rails_geokit plugin
or override source of named_scope 
Sandip Ransing wrote:
Marnen thx for reply !
Actually I wanted to add "OR" condition to acts_as_mappable finders, So that result-set will contain my own preferences too...but now it looks like for this purpose i may either need to mess up with library of rails_geokit plugin or override source of named_scope
No. Don't. It's a bad idea. It should never be necessary. Did you read the link I posted?
Best,
Marnen, I am not sure what you are saying should never be necessary. Suppose I have named_scope_a and named_scope_b. Are you saying it should never be necessary to find the set of records that includes all those in _a and those in _b? If not that then what is the best way? To provide a new named scope for the OR condition does not seem very DRY.
Colin
hmm. I gone through it … but its necessary for me. Is there any workaround ?
How about
result = (named_scope_1 + named_scope_2).uniq
That would loose the sort order I think, though one could always re-sort of course. Also could one use methods such as first on the result? Or apply another named scope to the result to further refine it?
Colin
Yes, the sort order gets lost.
When you add two named_scopes, the result is an Array. So you can call first on it, but you can't chain another named scope call to it.
Franz, what you said i was doing this but it’s not good performance wise as it fires 2 queries also purpose of pagination will be for toss bcoz it will load objects and then do pagination.
Colin, I am completely agree with your opinion and thinking there should be option for doing this.
Please don't top post, it makes it difficult to follow the thread.
Franz, what you said i was doing this but it's not good performance wise as it fires 2 queries also purpose of pagination will be for toss bcoz it will load objects and then do pagination.
Colin, I am completely agree with your opinion and thinking there should be option for doing this.
Also please quote the bit of the email you are responding to. What opinion of mine is it that you agree with? I was not aware that I had expressed any opinion on your suggestion.
Colin
Colin Law wrote:
No. �Don't. �It's a bad idea. �It should never be necessary. �Did you read the link I posted?
Marnen, I am not sure what you are saying should never be necessary. Suppose I have named_scope_a and named_scope_b. Are you saying it should never be necessary to find the set of records that includes all those in _a and those in _b?
No. I am saying that it should never be possible -- or necessary -- to do Person.scope_a.and_some_more_records . IMHO, that defeats the purpose of named_scopes, because the results of the scope chain are no longer guaranteed to be within scope_a. That's dangerous. If this syntax were possible, then there would be no obvious difference between a proper chain like Person.red_hair.blue_eyes and an improper chain like Person.red_hair.oh_and_everyone_else_too.
If not that then what is the best way? To provide a new named scope for the OR condition does not seem very DRY.
It's a completely different scope from either of its constituents. What's repetitive about that, particularly if you factor out duplication in other ways?
I'd actually support a syntax for union queries such as Person.union_scope(:scope_a, :scope_b). This makes it obvious that it is not a simple scope chain, while still being simple to call.
Colin
Best,
Colin Law wrote:
No. �Don't. �It's a bad idea. �It should never be necessary. �Did you read the link I posted?
Marnen, I am not sure what you are saying should never be necessary. Suppose I have named_scope_a and named_scope_b. Are you saying it should never be necessary to find the set of records that includes all those in _a and those in _b?
No. I am saying that it should never be possible -- or necessary -- to do Person.scope_a.and_some_more_records . IMHO, that defeats the purpose of named_scopes, because the results of the scope chain are no longer guaranteed to be within scope_a. That's dangerous. If this syntax were possible, then there would be no obvious difference between a proper chain like Person.red_hair.blue_eyes and an improper chain like Person.red_hair.oh_and_everyone_else_too.
Right, understood.
[...] I'd actually support a syntax for union queries such as Person.union_scope(:scope_a, :scope_b). This makes it obvious that it is not a simple scope chain, while still being simple to call.
Is that not what the OP was asking for in the original post to quote from there:
Is it possible to have two named scopes that can be joined using OR condition.
To which you replied:
Goodness, I hope not. That would be a terrible misuse of named_scopes.
Colin
Colin Law wrote: [...]
[...] I'd actually support a syntax for union queries such as Person.union_scope(:scope_a, :scope_b). This makes it obvious that it is not a simple scope chain, while still being simple to call.
Is that not what the OP was asking for in the original post to quote from there:
Is it possible to have two named scopes that can be joined using OR condition.
To which you replied:
Goodness, I hope not. That would be a terrible misuse of named_scopes.
I had thought that the OP was specifically asking about named_scope chaining with OR as in the other thread. On rereading, however, it seems that you're right and I misunderstood the question.
Colin
Best,
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