Apologies for the long title, but this is bothering me. I'm new to Rails, so this is my first project. Rails 3.0.3.
In my model, a User may or may not have read many Entries; this is tracked in a model called ReadEntries. This many-to-one relationship is properly defined in the code, I think.
User.rb:
has_many :read_entries
Entry.rb:
has_many :read_entries
ReadEntry.rb:
belongs_to :entry
belongs_to :user
This table has to be populated at some point. If I try to do this:
user.read_entries.find_or_create_by_entry_id(entry.id, :read => false)
I get the error Unknown key(s): read. Leave out trying to set :read, and it works.
However, if I create the same row with this, it works:
ReadEntry.find_or_create_by_entry_id_and_user_id(entry.id, user.id, :read => false)
Logically, these methods should be identical, right? Thanks.
I've also had weird experiences with find_or_create. I would love it if it worked, but it seems inconsistent.
I'm currently having the same issue as you, and I think it may be due to calling find_or_create on an association as opposed to the model directly. Here's my example:
permission_assignments.find_or_create_by_role_id(:role_id => role_id, :is_allowed => false)
This works to create the assignment, except the "is_allowed" field gets set to it's default of "true". This code works for me (in the Permission model, hence the self reference)
PermissionAssignment.find_or_create_by_permission_id_and_role_id(:permission_id => self.id, :role_id => role_id, :is_allowed => false)
It's more verbose, unfortunately, but it works. The only problem that I still notice is that the object that is returned has no id assigned (the record does get created in the database, however, but if I wanted to update any more attributes I wouldn't be able to without the id). Don't know if that's a separate issue or not.
Rails 3.0.4 here with Postgres 8.4
You cannot pass in other fields like that as Rails will assume they are options for the find. Instead, you will need to make your method call longer:
user.read_entries.find_or_create_by_entry_id_and_read(entry.id, false)
Or alternatively use a shorter, custom syntax for that.
For your final example, my thoughts are that Rails will take the second argument and use that as options. Other than that, I am not sure.
Related
I have a search form that queries one table in the database but there are many parameters (language, level, creator etc). The code below works provided the fields in question are filled in but I want to change it to:
a) add more parameters (there are several);
b) allow for a field to be empty
Here's the code in the controller:
#materials = Material.find(:all, :conditions => {:targ_lang => params["targ_lang"],
:inst_lang => params["inst_lang"],
:level => params["level"]})
Totally new to this I'm afraid but a lot of the documentation suggests I should be using "where".
Since Rails 3 you can use the where() function:
#materials = Material.where(targ_lang: params["targ_lang"], inst_lang: params["inst_lang"], level: params["level"])
Also, you could take a look at scopes
These allow you to set what you want to do in the model and call it in the controller for example:
class Material < ActiveRecord::Base
scope :active, where(active_state: true)
end
Then in the controller you do something like:
#active_materials = Material.active
This can be useful if you are joining several models and want to keep your controllers less messy.
To conclude, like #RVG said, seachlogic is quite useful as well as, there are others like Sphinx and Elastic Search. You should take a quick look at these and use the one you feel most confortable with.
If you are using search functionality in your app I suggest using SearchLogic gem
It is easy to use and effective..
SearchLogic
RailsCasts for searchlogic
I have heard couple of people complaining and posting questions about mass-assignment in Rails. I have got same error couple of times and all I did was attr_accessible. But what exactly is mass assignment? could somebody explain with example?
Mass Assignment is the name Rails gives to the act of constructing your object with a parameters hash. It is "mass assignment" in that you are assigning multiple values to attributes via a single assignment operator.
The following snippets perform mass assignment of the name and topic attribute of the Post model:
Post.new(:name => "John", :topic => "Something")
Post.create(:name => "John", :topic => "Something")
Post.update_attributes(:name => "John", :topic => "Something")
In order for this to work, your model must allow mass assignments for each attribute in the hash you're passing in.
There are two situations in which this will fail:
You have an attr_accessible declaration which does not include :name
You have an attr_protected which does include :name
It recently became the default that attributes had to be manually white-listed via a attr_accessible in order for mass assignment to succeed. Prior to this, the default was for attributes to be assignable unless they were explicitly black-listed attr_protected or any other attribute was white-listed with attr_acessible.
It is important to consider which attributes can be mass assigned because code like this is so common:
#post = Post.new(params[:post])
Typically this is used when the user submits a form rendered by a form_for #post. In an ideal world, the params[:post] hash should only contain the fields we displayed on the form. However, it is trivial easy for the user to pass additional fields in their request, so in effect you're allowing a user to set any fields on #post, not just the ones displayed on the form.
Failure to safely use mass assignment has led to several high profile bugs in some pretty big Rails applications, like the one that allowed somebody to inject their own public key into the list of trusted keys on a Github repository and push code directly to a repository they should not have had access to.
How can I validate uniqueness of an attribute with a custom or virtual scope? I thought of using a virtual attribute, but it keeps trying to query audit_year in the database. I would rather not create another database column just for the purpose of this uniqueness constraint.
Each location can only have one audit scheduled per year, so I need to extract the year from the scheduled attribute and validate uniqueness over that scope.
class Audit
attr_accessible :location_name, :scheduled_date, :completion_date ...
validates :location_name, :presence => true, :uniqueness => { :scope => :audit_year }
...
def audit_year
scheduled_date.year
end
end
I may not even be on the correct path with my virtual attribute attempts. What would be the "right" way to do this in rails?
I know this is a bit late, but I figured I'd pitch in. I'm doing this from memory so you may need to screw with this a bit.
My first thought is in your audit_year method, you could query the database for all years. Something like:
def audit_year
!self.class.select('selected_date').map{ |a| a.selected_date.year }.include?(selected_date.year)
# or using Rails 3.2 and Ruby 1.9.3:
# !self.class.pluck('created_at').map(&:year).include?(selected_date.year)
end
My assumption of the unique method is if it returns false, it will fail validation. This code selects just that one column from your class (I used self.class instead of Audit so it's more reusable), then maps out the years to an array. If it's included (true), return the opposite (!). You could probably optimize the query with uniq, but it depends on how large the table is whether it's necessary or not.
The other option would be to roll your own validator for the attribute, which really wouldn't be that difficult. The only difference is you'd add a line that conditionally checks for selected_date.present? in addition to the above. A great resource is the Rails Guides for callbacks and errors if you don't know how: http://guides.rubyonrails.org/active_record_validations_callbacks.html
Hope that helps.
I have the following associations set up
class bookinghdr
belongs_to :agent
end
class bookingitem
belongs_to :bookinghdr, :include => agent
end
So I was expecting to be able to do the following:
named_scope :prepay, :include=>["bookinghdr"], :conditions => ["bookinghdr.agent.agenttype = 'PP'"]
and in my controller do:
b = Bookingitem.prepay
But that gives me a ActiveRecord::StatementInvalid: Mysql::Error: Unknown column 'bookinghdr.agent.agenttype'
However if I don't include the conditions clause then I get a recordset on which I can do:
b = Bookingitem.prepay
b[0].bookinghdr.agent.agenttype
without any error!
I don't want to have to get all the records and then iterate over them to find the ones whose agent has a 'PP# flag. I was hoping that AR would do that for me.
Anybody got any ideas on how to achieve this?
Your question shows that you have not yet fully understood how associations and named scopes work. Since I cannot tell from your question what parts aren't clear, I suggest you read the Association Basics guide at http://guides.rubyonrails.org/v2.3.11/association_basics.html. This should bring you up to speed regarding the concepts you want to implement. After you have read the guide it should all make sense.
So, I tried to search for an example of how to do this, and I'm not sure I even know how to describe what I'm trying to do. I'm an utter noob when it comes to SQL, and I'm sure this is really basic but I'm totally lost:
I have a model, Photo, which has_many :tags, :through => :taggings. Tags have a name and an id.
I want to do something like: Photo.where( #tag_name in [array] )
... but like I said I have no idea how to write something like that, or what to search to see an example on Google.
Can anyone give me an example of that kind of query, and what it might be called?
Thanks!
Just tried this on a similar model of my own and seemed to work fine:
Photo.joins(:tags).where('tags.name' => ['herp','derp']).group(:id)
Also, here's a great resource on the AREL querying interface rails 3 uses, with information on these and other ActiveRecord calls related to querying.
So, as a twist on Brett's method, it turns out the following works without breaking PostgreSQL:
def self.tagged_with( string )
array = string.split(',').map{ |s| s.lstrip }
select('distinct photos.*').joins(:tags).where('tags.name' => array )
end
Problem solved! See this article for a great explanation as to why this is a better idea than 'group'.