In my articles model, I created a scope that links categories to their
respective articles posts. When I use the rails console, the method
works perfectly when I query the db.
article.rb
scope :category_technology, -> {where(category_id: 1)}
@articles.category_technology
Article Load (0.5ms) SELECT “articles”.* FROM “articles” WHERE
“articles”.“category_id” = ? ORDER BY “articles”.“created_at” DESC
[[“category_id”, 1]]
Which works.
The problem is that I’m unable to use it in the view and iterate over
the records with category_id: 1.
What I’d like to do is something like this
technology_controller.rb
def index
@technology_articles = Article.category_technology.all.limit(10).last
end
In the index.html.erb
<% if @technology_articles.present? %>
<% @technology_articles.each do |article| %>
<- omitted ->
<% end %>
I’m getting undefined method `each’ for #Article:0x8300868
Can you help?
Btw, it does work in the Rails Console.
Article.category_technology.limit(10).last
On 9 March 2016 at 21:51, David W. [email protected] wrote:
“articles”.“category_id” = ? ORDER BY “articles”.“created_at” DESC
[[“category_id”, 1]]
Which works.
Is that not just the same as @category.articles assuming that @category
has id 1
The problem is that I’m unable to use it in the view and iterate over
the records with category_id: 1.
What I’d like to do is something like this
technology_controller.rb
def index
@technology_articles = Article.category_technology.all.limit(10).last
Again, you would be better to do it the other way around, start with
the category and get the articles from that. Note, however that as
you have coded it you have specifed .last which means that
@technology_articles is only one article, not a collection.
I’m getting undefined method `each’ for #Article:0x8300868
That is because you only have a single Article, not a collection, see
above.
Colin
Colin L. wrote in post #1182073:
On 9 March 2016 at 21:51, David W. [email protected] wrote:
“articles”.“category_id” = ? ORDER BY “articles”.“created_at” DESC
[[“category_id”, 1]]
I’m getting undefined method `each’ for #Article:0x8300868
That is because you only have a single Article, not a collection, see
above.
Colin
Thanks for responding Colin, I didn’t realize .last would lead to a
single article being queried. I thought it would give me the last 10
records. I guess DESC being my default named_scope: default_scope → {
order(created_at: :desc) } should take care of that for me. Thank you
again.
On 9 March 2016 at 22:25, David W. [email protected] wrote:
Colin
Thanks for responding Colin, I didn’t realize .last would lead to a
single article being queried. I thought it would give me the last 10
records. I guess DESC being my default named_scope: default_scope → {
order(created_at: :desc) } should take care of that for me. Thanks.
The limit(10) gives you the first ten records, but since you have
ordered descending that means you will get the ten with the highest
created_at. Although default_scope sounds like a good idea I have
several times used it only to find that it causes confusion and now
avoid it. Preferring to explicitly specify the order whenever it
matters (via named scopes if appropriate).
Colin
The limit(10) gives you the first ten records, but since you have
ordered descending that means you will get the ten with the highest
created_at. Although default_scope sounds like a good idea I have
several times used it only to find that it causes confusion and now
avoid it. Preferring to explicitly specify the order whenever it
matters (via named scopes if appropriate).
Part of one of the RailsConf sessions I went to, either last year or the
year before, could have been re-titled “default_scope considered
harmful”. I don’t think it’s deprecated or anything, but it is
definitely something to use sparingly, and with a lot of forethought
about what other scopes you may need later. Better to chain scopes, so
you call ControllerName.your_scope.latest, rather than adding the
“latest” behavior into your default scope. It makes it more declarative.
More (duplicated) characters is not really the issue you want to
prioritize. Being able to reason about your code in the current bit you
are working on is.
Walter
Walter D. wrote in post #1182112:
Part of one of the RailsConf sessions I went to, either last year or the
year before, could have been re-titled “default_scope considered
harmful”. I don’t think it’s deprecated or anything, but it is
definitely something to use sparingly, and with a lot of forethought
about what other scopes you may need later. Better to chain scopes, so
you call ControllerName.your_scope.latest, rather than adding the
“latest” behavior into your default scope. It makes it more declarative.
More (duplicated) characters is not really the issue you want to
prioritize. Being able to reason about your code in the current bit you
are working on is.
Walter
Very true. Thank you for your advice.