If I don’t have row with id=params[:id] how can i check it, since
when I write
def show
#post=Post.find(params[:id])
if #post.nil?
#post={
title:"No such post",
post:"No such post"
}
end
end
I get error.
From the fine manual:
find(*args)
Find by id - This can either be a specific id (1), a list of ids (1, 5, 6), or an array of ids ([5, 6, 10]). If no record can be found for all of the listed ids, then RecordNotFound will be raised.
So if find can't find anything with the id you're looking for, it raises an ActiveRecord::RecordNotFound exception rather than return nil like you want it to. That exception ends up being handled deep inside Rails and gets converted to a 404.
You could trap that exception yourself:
def show
#post = Post.find(params[:id])
rescue ActiveRecord::RecordNotFound
#post = {
title: "No such post",
post: "No such post"
}
end
Note that you'd only trap the specific exception you're expecting to see, a bare rescue is almost always a mistake because it can hide bugs.
You could also use find_by:
find_by(*args)
[...]
If no record is found, returns nil.
like this:
def show
#post = Post.find_by(:id => params[:id])
if #post.nil?
#post = {
title: "No such post",
post: "No such post"
}
end
end
Exceptions are meant for handling errors and other exceptional conditions, they're not meant to be used for normal flow control. I'd probably use find_by for this sort of thing; it seems that you're expecting the occasional missing record so it a missing record isn't really an error or an unexpected condition.
show controller is expected to show existing elements only. When an element (Post instance) does not exist, find throws an exception. As #Michal suggested in the comments, usually non-existing entities are being handled with 404 response, or like.
For the time, being, though, you might cheat Rails with:
#post = Post.find(params[:id]) rescue {
title: "No such post",
post: "No such post"
}
This is not a production solution, of course, but it might help during learning phase.
Related
after setup a search into a serializer!
Rails spits out
no implicit conversion of nil into Hash
So, please someone can point out whats wrong with this code?
class SearchController < ApplicationController
def results
results_query = PgSearch.multisearch(params[:q]).paginate(page: page, per_page: 20)
result = results_query.map(&:searchable).map do |result_item|
case result_item.class.name
when 'Post'
PostSerializer.new(result_item)
else
raise NotImplementedError
end
end
render json: {
items: result,
page: page,
pages: results_query.total_pages
}
end
def page
params[:page] || 1
end
def serialize(data, serializer)
ActiveModel::Serializer::CollectionSerializer.new(data, each_serializer: serializer)
end
end
Since your case statement isn't checking many values, you could always make it into a standard if/else statement:
if result_item && result.class.name == 'Post'
PostSerializer.new(result_item)
else
raise NotImplementedError
end
Well, on the screenshots you've provided we can see the log message specifies that the error is on line 5.
According to your code, line 5 is: case result_item.class.name
The error message is TypeError (no implicit conversion of nil into Hash).
You're trying to get the class then the name of result_item. So the problem is with result_item which is equal to nil.
In order the resolve your problem you might want to check the ouput of results_query.map(&:searchable).map.
Based on the screenshot you've provided, I've quickly checked the source code. The offending line seems to be this one: https://github.com/Casecommons/pg_search/blob/master/lib/pg_search/document.rb#L22. The only reason why this would raise the described TypeError is if PgSearch.multisearch_options is nil – which, as far as I understand the code, would only be possible if you accidentally overwrote it in a wrong way. So I'd suggest doublechecking your global setup for PgSearch.multisearch_options to make sure this is actually set.
The east way to check the setting is by using a debugger or putting something like puts PgSearch.multisearch_options or Rails.logger.info 'PgSearch.multisearch_options' into the controller directly above the call that's failing.
I'm starting to know ROR and I was doing a kind of blog with articles, etc...
I did this code :
def show
id = params[:id]
list = Article.all
is_valid = false
list.all.each do |article|
if article.id == id
#is_valid = true
break
end
end
As you can see, this code just wants to check if the article ID exists or not. So I'm testing equality between id and article.id (which's a model linked to the appropriated table in the database) BUT when I try to use or display #is_valid boolean I saw that article.id == id is FALSE every time, even if article.id = 2 and id = 2. I tried to think about everything that can make this occuring, but I admit I still misunderstand this.
Then I ask you if you know why this is occuring. Of course, an equality like 2 == 2 will change #is_valid to true.
Thank you for your help !
Maybe its because params[:id] it's a string and article.id it's an Integer
(byebug) params
{"controller"=>"admin/my_controller", "action"=>"edit", "id"=>"1"}
And yes it is... "id" is a string "1", so you may try this:
def show
id = params[:id].to_i
list = Article.all
is_valid = false
list.all.each do |article|
if article.id == id
#is_valid = true
break
end
end
end
And maybe could work.
This is the answer to your question,
But if you want to learn a little more about Activerecord you can do this
Article.exists?(params[:id])
and that will do what you are trying to do just with a query against db.
and if you want to get just a simple article
record = Article.find_by(id: params[:id]) #return nil when not exist
if record # if nil will threat like false on ruby
#my code when exist
else
#my code when not exist
end
will work (you also can use find but find will throw an exception ActiveRecord::RecordNotFound when not exists so you have to catch that exception.
Activerecord has many ways to check this you dont need to do it by hand.
def show
#article = Article.find(params[:id])
end
This will create a database query which returns a single row. .find raises a ActiveRecord::NotFound exception if the record is not found. Rails catches this error and shows a 404 page. Article.find_by(id: params[:id]) is the "safe" alternative that does not raise.
Your code is problematic since list = Article.all will load all the records out of the database which is slow and will exhaust the memory on the server if you have enough articles. Its the least effective way possible to solve the task.
If you want to just test for existence use .exists? or .any?. This creates a COUNT query instead of selecting the rows.
Article.where(title: 'Hello World').exists?
I have code in my Rails app that allows me to export a CSV file. It works fine unless there is a record that has a field with no value in it. In that case it fails. As an example, the specific failure I'm getting is saying something liek "No Method Error" and it specifically references "address_line_1" because there are some users with no address_line_1. That is just one example though. Really all fields should be protected against potential blanks. Here is the code:
def download_kids_csv
#csv_headers = ['First',
'Last',
'Child First',
'Child Last',
'Parent Email',
'School',
'Class',
'Address',
'City',
'State',
'Zip',
'Parent Phone']
#kid_data = []
#school = School.find(params[:school_id])
#school.classrooms.each do |classroom|
classroom.kids.includes(:users).each do |kid|
kid.users.each do |parent|
#kid_data << {
first: parent.first_name,
last: parent.last_name,
child_first: kid.first_name,
child_last: kid.last_name,
parent_email: parent.email,
school: #school.name,
class: classroom.classroom_name,
address: parent.addresses.first.address_line_1,
city: parent.addresses.first.city,
state: parent.addresses.first.state,
zip: parent.addresses.first.zip_code,
parent_phone: parent.phones.first.phone_number
}
end
end
end
respond_to do |format|
format.csv do
headers['Content-Disposition'] = "attachment; filename=\"#{#school.name.downcase.gsub(' ', '-')}-data.csv\""
headers['Content-Type'] ||= 'text/csv'
end
end
end
Ok so the problem you are get is because you are calling method on a nil value.
So for example when you do:
kid.first_name
and kid is nil you are doing this
nil.first_name
nil does not implement the first_name method so it throws an error. WHat you could do to circumvent this (its kinda ugly) is this
kid.try(:first_name)
This will prevent you form getting those method missing errors
For those long chains you can do the following
parent.try(:addresses).try(:first).try(:zip_code)
This should save you a lot of headache, but the root cause of your issue is data integrity you would not have to do all of this if you ensured that your data was not blank. I do however understand in the real world it easier said than done. I could give you a lecture about The Law of Demeter and how you should not be running across object to access their attributes, and how thats a code smell of bad organization of data, but its a spread sheet and sometimes you just need the data. Good luck!
To build off of the earlier answer, you can also utilize the so-called lonely operator &. if you're on Ruby 2.3.
An example would look something like this: kid&.first_name.
If you're not on that version of ruby yet, there's a good gem that can help you out in this situation that's a little bit more robust than .try.
Using that gem your code would look like kid.andand.first_name. It might be overkill in this case but the difference here is that it will only perform the first_name method call if kid is not nil. For your longer chains, parent.address.first.zip_code, this would mean that the function chain would exit immediately if parent was nil instead of calling all of the different attributes with try.
Is it possible to use unless or another conditional?
unless parent.addresses.first.address_line_1.blank?
address: parent.addresses.first.address_line_1,
end
or
if parent.addresses.first.address_line_1 != nil
address: parent.addresses.first.address_line_1,
else
address: nil || "address is empty"
end
I am running a spree app.
I am getting below error when I try to add any product in the cart.
undefined method `+' for nil:NilClass
This error comes only when I add option types and variants of the same product.
I am not sure what's exactly going wrong here, because I am not doing any changes in the code or something.
This is the extracted source it shows.
if quantity.between?(1, 2_147_483_647)
begin
order.contents.add(variant, quantity, options)
rescue ActiveRecord::RecordInvalid => e
error = e.record.errors.full_messages.join(", ")
end
Here's my order controller's populate function.
# Adds a new item to the order (creating a new order if none already exists)
def populate
order = current_order(create_order_if_necessary: true)
variant = Spree::Variant.find(params[:variant_id])
quantity = params[:quantity].to_i
options = params[:options] || {}
# 2,147,483,647 is crazy. See issue #2695.
if quantity.between?(1, 2_147_483_647)
begin
order.contents.add(variant, quantity, options)
rescue ActiveRecord::RecordInvalid => e
error = e.record.errors.full_messages.join(", ")
end
else
error = Spree.t(:please_enter_reasonable_quantity)
end
if error
flash[:error] = error
redirect_back_or_default(spree.root_path)
else
respond_with(order) do |format|
format.html { redirect_to cart_path }
end
end
end
Please help me out here.
You need to ensure the values of variant, quantity and options before sending them to spree.
The fact that you get this error could be considered as a bug on their side, since you'd expect a nice error message saying "variant is nil" or the like.
To fix your problem though, I'd check that these values are valid ones before sending them to spree.
For future views about this issue.
Check if the Variant cost_currency attribute is the same that is configured in Spree. You can check it in a rails console doing:
Spree::Config.get(:currency)
Sometimes it happens when spree is initialized with some currency by default and then the default currency is changed.
I'm trying to delete a record by passing id of that record. The code looks like this:
def destroy_catalogue_entry
#catalogue_entry = CatalogueEntry.find(params[:catalogue_entry_id])
if #catalogue_entry.destroy
flash[:success] = 'Catalogue entry deleted successfully.'
else
flash[:error] = 'Failed...'
end
end
I'm getting an interesting error. When my function destroy_catalogue_entry is called it shows:
Couldn't find CatalogueEntry with 'id'=16
but as I comment If condition section and render #catalogue_entry as json, the output is printed successfully. So how is it possible? Am I making some silly mistake or is there logical reason. Please enlighten me.
Solved! All I did is this:
def destroy_catalogue_entry
#catalogue_entry = CatalogueEntry.find(params[:catalogue_entry_id])
if #catalogue_entry.destroy
flash[:success] = 'Catalogue entry deleted Successfully'
redirect_to action: :view_catalogue_entries, dc_id: #catalogue_entry.dc_id
else
flash[:success] = 'Failed...'
end
end
When I notice the console, the record was getting deleted successfully but after that there was a SELECT query for the same record, that is why it was throwing the error Couldn't find CatalogueEntry with 'id'=16. As I redirected it, the problem was solved.
I think destroy method is returning an object. In ruby anything other than false or null will be taken to true in if statement. You can do puts on destroy method and see what its returning.
i presume your,
#catalogue_entry = CatalogueEntry.find(params[:catalogue_entry_id])
is returning that error because it cant find CatalogueEntry with id 6, make sure you have CatalogueEntry with that id.