I have got a few models that are different types of user account - i.e. a User model, an Admin model, a Guest model.
I'm trying to create a forum as part of an application I am making. When a post is created, the user_type attribute is set to the type of user that created the post. What I want to do seems to be something pretty simple, but I can't seem to work it out. Basically, I want to get the username of the person that created the post. I can't just use something like post.user.username, as I have a few different models, and I don't want to have to do something ugly with if statements, so is there a better way around? This might show what I'm trying to achieve (although this doesn't work):
created by:<%= post.#{user_type}.username %>
which would then output to the relevant code:
post.user.username
or post.admin.username
or post.guest.username
Thanks!
Maybe your best course of action
class Post < ActiveRecord::Base
...
def username
[user,admin,guest].find(&:present?).try(:username)
end
end
You can stick this in your model, or even better, a decorator.
Now you can just do this in your view:
created by:<%= post.username %>
find retrieves the first thing that responds to present?. In other words, it finds the first thing that is not nil. Then, we try to call username on whatever that method returns. If there is no user, admin, or guest for this post, the method will return nil.
Related
I've a user profile (with name, logo, about_me) which is created after user creation(using Devise). Profile table uses user_id as Primary key.
Now I want that whenever the user creates/updates a post, while filling in form some details are taken from profile, so profile data or #profile be available in post form as I cannot expose my model in form.
To set post.myname attribute in create and #update I'm doing this:
#myprofile = Profile.find_by_user_id(current_user)
write_attribute(:myname, #myprofile.name)
I read from various sources but what's the best solution of the 4 given and if anyone can back with easy code as I do not want to do something extensive? Thanks in advance.
1)Form Hidden fields - Like get the profile data as above in hash in #edit and then pass through form and access fields in #update but that way we will pass each field separately. Can one #myprofile be passed?
2)Session - I feel if profile data is stored in a session and someone updates profile then updated data won't be available in that session.So not sure if it is plausible.
3)Caching - easy way to do that?
4)polymorphic profile---tried it but I didnot get relevant example. I was stuck with what to put as profileable id and type and how to use them in the code.
If your Profile and User models have a one-to-one relationship with each other, the simplest solution is to remove the Profile model altogether and move its fields into the User model.
Devise already queries the database to obtain the current_user object. So, your example would like this:
write_attribute(:myname, current_user.name)
Which wouldn't hit the database (after Devise has retrieved the current_user object).
If you're forced to keep the Profile model, in looking at your four scenarios ...
You could use a session variable. Something like:
session[:profile_name] ||= #myprofile.name
This would go in a controller action.
The trick here is that you will want to redefine the each relevant session variable if the profile gets updated. And because you don't have access to the session in the model, you'd be best to perform that action in the controller. So, not pretty, but it could work.
You could also use low-level caching, and save the profile relationship on the user. In general, you could have a method like this in your user model:
def profile_cached
Rails.cache.fetch(['Profile', profile.id]) do
profile
end
end
Here, too, you will have to know when to expire the cache. The benefit of this approach is that you can put this code in the model, which means you can hook its expiration in a callback.
Read more about this in Caching with Rails.
I would avoid hidden fields and I'm not sure how a polymorphic relationship would solve you not hitting the database. So, #2 and #3 are options, but if you can combine the two models into one, that should simplify it.
I am using form_for in the _form.html.erb view in order to create my form for both the edit and new actions, as per a standard scaffold.
I have a model Owner which has_many pets.
I would like to put an html link on my views/owners/show.html.erb to create a new pet for said owner. This link will point to the new action of pets_controller.rb which when accessed will render the view in pets/new.html.erb
What I want to happen is for the the owner_id to be passed with the link in the url to the new action of pets_controller.rb and then be used as the default for a collection_select in pets/new.html.erb
So I have a link to create a new pet but because that link was on a specific owner page, I want the form to create a new pet to have that owner already set, so the user does not have to select from the list.
This has to be done without changing the behaviour of the edit action/view in pets.
I know that I can pass GET arguments then access them in the controller via params, then create variables in the action which are passed to the view. I can then manually check for a default and set it in the view. I do not need assistance in coding if this is the only solution.
Is there is a better way to do this? A format with which I can pass the params such that the view will just pick them up? Without manually editing my controllers and views?
While my personal inclination would be to do as you said and pass a parameter in the link helper and then access the params array in the pets view, you may find that this is the perfect opportunity to explore Nested Resources. Essentially, you could declare owners/:owner_id/pets/:pet_id route with:
resources :owners do
resources :pets
end
You could then link to this route, and reference :owner_id without having to append the query string to the URI (making somewhat cleaner for reuse).
This is likely more work for you, but also potentially more extensible (and certainly more inline with the Rails way of doing things).
REVISION
Added the following regarding link helpers to the comments, but wanted to reflect it in the answer as well.
To show a pet should be:
<%= link_to owner_pet_path( owner_variable, pet_variable) %>
To view pets' index index should be:
<%= link_to owner_pet_path( owner_variable ) %>
The answer given to this question is fantastic.
As #ConnorCMcKee suggests it would be wise to consider nesting your routes. However, if you are a beginner as myself I found that it helped my learning to simply nest my second controller into the first (i.e. nest PetsController into OwnersController) as a first step. Then afterwards I would continue with the routes.
The method would be something like:
1./ In owners/index.html.erb:
Links to PetsController index action
The key to make this work is to send the :owner_id in your link parameters. Then that Pets index action will have access to that :owner_id and know which :owner_id called it.
2./ In PetsController you would then be able to find that Owner using that id, like so:
params[:owner_id]
Then your actions can start to take advantage of knowing what Owner called them. Remember though that all your redirects inside your PetsController need to preserve params[:owner_id]. That is because once you are inside that nested structure you have to maintain it and stay inside it and always know which :owner_id you are working with.
I have a model Post, which is submitted and graded by different Users. The submitter and grader are identified by submitter_id and grader_id in Post model. Note that an user is both a submitter himself and a grader to others.
I want to make sure that the submitter can only edit the content of the Post but not the grade. Likewise, the grader can only edit the grade but not the content.
Is multiple edit methods the way to go? How should I accomplish this otherwise?
You can have a role column in your users table, and the role can be either submitter or grader. Not sure what you are using for authentication, but in case you are using devise, you can access the currently logged in user with current_user helper (in case you are using something else, figure this part out, or add a new helper).
Now in your update method, you can do something like this:
# Controller
# scope post to current user, so that a user cannot edit someone else's post. A crude way to achieve this is post = Post.find(params[:id])
post = current_user.posts.find(params[:id])
post.content = params[:content] if post.submitter?(current_user.id)
post.grade = params[:grade] if post.grader?(current_user.id)
post.save!
# Model - Post.rb
def submitter?(user_id)
self.submitter_id == user_id
end
def grader?(user_id)
self.grader_id == user_id
end
The advantage of keeping those methods in the model is that in case you permission logic changes (who is submitter, or a grader), you need to change it at a single location. DRY.
You can modify the above approach to show error messages, and do other similar stuff. In case you are looking for more granular authorization control, you can look into cancan gem:
https://github.com/ryanb/cancan
Your post model should only be concerned with persisting data. Better to use plain old ruby objects to encapsulate the higher order behavior of grading and submitting. Consider using service objects or form objects.
Each service or form object can then include ActiveModel::Model(rails > v4) to get its own validations.
See more about service and form objects here: http://blog.codeclimate.com/blog/2012/10/17/7-ways-to-decompose-fat-activerecord-models/
If you only have one submit action and one grade action, its probably ok to keep in one controller. But if you start having multiple actions that are related to submitted, and multiple actions that are related to grading, this sounds like they would make great resources controllers on their own.
I want to restrict users to voting up or down on posts and each User can only cast one vote for each Post. I have to check if the User voted on the post before I create a new relation.
I am already using CanCan for other restrictions like "the User can only edit its own Post", but this case is something different, so I want the best practice. After adding an uniqueness-validation to the model should I implement the rule above ("one vote per post and user") via CanCan or just in the controller?
To me it sounds like neither, this is a validation that should be performed in the model layer IMO.
To me, this is not a CanCan job. On a cursory review of the issue, my sense is that I would create a predicate method in the model and call that from my view.
def votable?
if blahblahblag
true
else
false
end
end
In the (haml) view:
- if model_name.votable?
= cool_markup_tag
Something like that ... just a rough sketch but, to me, this keeps the controller clean and the check in the model where I think it belongs (and is along Logan's comment/answer).
I've been researching this topic for a day now, and I haven't seen a solution that could adequately allow this. I would have even give up and said that it's not possible, but I see large companies achieving this in their apps!
I need to know if the current user is following another user. I need to know this many times (for the current_user) without polling the DB again
The solution needs to be friendly for reuse. A solution (that's not friendly for reuse) I had come up with is as follows:
module UsersHelper
def is_following?(user)
return false if current_user == user
user.is_following = Relationship.find_by(followed_id: user.id, follower_id: current_user.id)
end
end
is_following?(#user) can now be called in any controller
Notice that I'm able to access current_user because this helper method will be called in a controller, not a model.
This implementation is cool for one model, maybe two... except I need to do this in almost every many-many relationship I have in the app. So it has to be scalable.
I'm referencing exactly what Twitter does with their following.