Probably really easy but im having trouble finding documentation online about this
I have two activerecord queries in Ruby that i want to join together via an OR operator
#pro = Project.where(:manager_user_id => current_user.id )
#proa = Project.where(:account_manager => current_user.id)
im new to ruby but tried this myself using ||
#pro = Project.where(:manager_user_id => current_user.id || :account_manager => current_user.id)
this didnt work, So 1. id like to know how to actually do this in Ruby and 2. if that person can also give me a heads up on the boolean syntax in a ruby statement like this altogether.
e.g. AND,OR,XOR...
You can't use the Hash syntax in this case.
Project.where("manager_user_id = ? OR account_manager = ?", current_user.id, current_user.id)
You should take a look at the API documentation and follow conventions, too. In this case for the code that you might send to the where method.
This should work:
#projects = Project.where("manager_user_id = '#{current_user.id}' or account_manager_id = '#{current_user.id}'")
This should be safe since I'm assuming current_user's id value comes from your own app and not from an external source such as form submissions. If you are using form submitted data that you intent to use in your queries you should use placeholders so that Rails creates properly escaped SQL.
# with placeholders
#projects = Project.where(["manager_user_id = ? or account_manager_id = ?", some_value_from_form1, some_value_from_form_2])
When you pass multiple parameters to the where method (the example with placeholders), the first parameter will be treated by Rails as a template for the SQL. The remaining elements in the array will be replaced at runtime by the number of placeholders (?) you use in the first element, which is the template.
Metawhere can do OR operations, plus a lot of other nifty things.
Related
I can do this code:
params.require(:something).permit(:param_a,:param_b)
And this:
params.require(:something).permit(:param_a,:param_c_attributes:[])
My problem is that I need to select the permit parameters depending if some parameter exists. So I tried:
premit_params = {:param_a,:param_c_attributes:[]}
premit_params = {:param_a,:param_d} if params[:something] && params[:something][:param_d]
params.require(:something).permit(premit_params)
But it's not working.
BTW: Using Rails 5.1
It doesn't work because permit doesn't expect a hash as an argument, but a list of parameters.
Collect your arguments in an array and split that array with the splat operator (*) to list or arguments:
premit_params = [:param_a, { :param_c_attributes: [] }]
premit_params = [:param_a, :param_d] if params.dig(:something, :param_d)
params.require(:something).permit(*premit_params)
You can check if the parameter you want exits
For Example:
if (user_params.has_key?(:name))
end
Moreover, parameters are saved in hash so you have different methods you can use to apply your logic
https://ruby-doc.org/core-1.9.3/Hash.html
I am new to Ruby, so let me describe the context of my problem first:
I have a json as input which has the following key / value pair:
{
"service": "update"
}
The value has many different values for example: insert,delete etc.
Next there is a method x which handles the different requests:
def x(input)
case input[:service]
services = GenericService.new
when "update"
result = services.service(UpdateService.new,input)
when "insert"
result = services.service(InsertService.new,input)
when "delete"
result = services.service(DeleteService.new,input)
....
....
else
raise "Unknown service"
end
puts JSON.pretty_generate(result)
end
What is bothering me is that I still need to use a switch statement to check the String values (reminds me of 'instance of' ugh..). Is there a cleaner way (not need to use a switch)?
Finally I tried to search for an answer to my question and did not succeed, if however I missed it feel free to comment the related question.
Update: I was thinking to maybe cast the string to the related class name as follows: How do I create a class instance from a string name in ruby? and then call result = services.services(x.constantize.new,input) , then the class names ofcourse needs to match the input of the json.
You can try something like:
def x(input)
service_class_name = "#{input[:service].capitalize}Service"
service_class = Kernel.const_get(service_class_name)
service_class.new(input).process
end
In addition you might want to check if this is a valid Service class name at all.
I don't understand why you want to pass the service to GenericService this seems strange. let the service do it's job.
If you're trying to instatiate a class by it's name you're actually speaking about Reflection rather than Polymorphism.
In Ruby you can achieve this in this way:
byName = Object.const_get('YourClassName')
or if you are in a Rails app
byName= 'YourClassName'.constantize
Hope this helps
Just first thoughts, but you can do:
eval(services.service("#{input[:service].capitalize}Service.new, #{input})") if valid_service? input[:service]
def valid_service?
w%(delete update insert).include? input[:service]
end
As folks will no doubt shout, eval needs to be used with alot of care
This is a sort of followup to my other MongoDB question about the torrent indexer.
I'm making an open source torrent indexer (like a mini TPB, in essence), and offer both SQLite and MongoDB for backend, currently.
However, I'm having trouble with the MongoDB part of it. In Sinatra, I get when trying to upload a torrent, or search for one.
In uploading, one needs to tag the torrent — and it fails here. The code for adding tags is as follows:
def add_tag(tag)
if $sqlite
unless tag_exists? tag
$db.execute("insert into #{$tag_table} values ( ? )", tag)
end
id = $db.execute("select oid from #{$tag_table} where tag = ?", tag)
return id[0]
elsif $mongo
unless tag_exists? tag
$tag.insert({:tag => tag})
end
return $tag.find({:tag => tag})[:_id] #this is the line it presumably crashes on
end
end
It reaches line 105 (noted above), and then fails. What's going on? Also, as an FYI this might turn into a few other questions as solutions come in.
Thanks!
EDIT
So instead of returning the tag result with [:_id], I changed the block inside the elsif to:
id = $tag.find({:tag => tag})
puts id.inspect
return id
and still get an error. You can see a demo at http://torrent.hypeno.de and the source at http://github.com/tekknolagi/indexer/
Given that you are doing an insert(), the easiest way to get the id is:
id = $tag.insert({:tag => tag})
id will be a BSON::ObjectId, so you can use appropriate methods depending on the return value you want:
return id # BSON::ObjectId('5017cace1d5710170b000001')
return id.to_s # "5017cace1d5710170b000001"
In your original question you are trying to use the Collection.find() method. This returns a Mongo::Cursor, but you are trying to reference the cursor as a document. You need to iterate over the cursor using each or next, eg:
cursor = $tag.find_one({:tag => tag})
return cursor.next['_id'];
If you want a single document, you should be using Collection.find_one().
For example, you can find and return the _id using:
return $tag.find_one({:tag => tag})['_id']
I think the problem here is [:_id]. I dont know much about Mongo but `$tag.find({:tag => tag}) is probably retutning an array and passing a symbol to the [] array operator is not defined.
I have a Rails app that has a COUNTRIES list with full country names and abbreviations created inside the Company model. The array for the COUNTRIES list is used for a select tag on the input form to store abbreviations in the DB. See below. VALID_COUNTRIES is used for validations of abbreviations in the DB. FULL_COUNTRIES is used to display the full country name from the abbreviation.
class Company < ActiveRecord::Base
COUNTRIES = [["Afghanistan","AF"],["Aland Islands","AX"],["Albania","AL"],...]
COUNTRIES_TRANSFORM = COUNTRIES.transpose
VALID_COUNTRIES = COUNTRIES_TRANSPOSE[1]
FULL_COUNTRIES = COUNTRIES_TRANSPOSE[0]
validates :country, inclusion: { in: VALID_COUNTRIES, message: "enter a valid country" }
...
end
On the form:
<%= select_tag(:country, options_for_select(Company::COUNTRIES, 'US')) %>
And to convert back the the full country name:
full_country = FULL_COUNTRIES[VALID_COUNTRIES.index(:country)]
This seems like an excellent application for a hash, except the key/value order is wrong. For the select I need:
COUNTRIES = {"Afghanistan" => "AF", "Aland Islands" => "AX", "Albania" => "AL",...}
While to take the abbreviation from the DB and display the full country name I need:
COUNTRIES = {"AF" => "Afghanistan", "AX" => "Aland Islands", "AL" => "Albania",...}
Which is a shame, because COUNTRIES.keys or COUNTRIES.values would give me the validation list (depending on which hash layout is used).
I'm relatively new to Ruby/Rails and am looking for the more Ruby-like way to solve the problem. Here are the questions:
Does the transpose occur only once, and if so, when is it executed?
Is there a way to specify the FULL_ and VALID_ lists that do not require the transpose?
Is there a better or reasonable alternate way to do this? For instance, VALID_COUNTRIES is COUNTRIES[x][1] and FULL_COUNTRIES is COUNTRIES[x][0], but VALID_ must work with the validation.
Is there a way to make a hash work with just one hash rather then one for the select_tag and one for converting the abbreviations in the DB back to full names for display?
1) Does the transpose occur only once, and if so, when is it executed?
Yes at compile time because you are assigning to constants if you want it to be evaluated every time use a lambda
FULL_COUNTRIES = lambda { COUNTRIES_TRANSPOSE[0] }
2) Is there a way to specify the FULL_ and VALID_ lists that do not require the transpose?
Yes use a map or collect (they are the same thing)
VALID_COUNTRIES = COUNTRIES.map &:first
FULL_COUNTRIES = COUNTRIES.map &:last
3) Is there a better or reasonable alternate way to do this? For instance, VALID_COUNTRIES is COUNTRIES[x][1] and FULL_COUNTRIES is COUNTRIES[x][0], but VALID_ must work with the validation.
See Above
4) Is there a way to make the hash work?
Yes I am not sure why a hash isn't working as the rails docs say options_for_select will use hash.to_a.map &:first for the options text and hash.to_a.map &:last for the options value so the first hash you give should be working if you can clarify why it is not I can help you more.
I have a collection of objects. There are 3 properties in each object
'id', 'name', 'is_primary'
The collection of objects will usually have anywhere from 1 to 5 objects.
What I want to do is check the collection to see if is_primary is true. If so output the name, or at least return it.
I want to do this in 1 line of code if possible. I am trying to slim up this one line for erb output in rails. Later in the page i'll output them all. I thought I had it, but if I return nil it adds extra space which shifts all the html oddly.
Thanks.
Hmm, this doesn't quite work if no element is_primary...I'm still thinking...
c.detect(&:is_primary).name
Ok, how about:
((a = c.detect(&:is_primary)) && a.name).to_s
As it happens, it is OK in an erb template for the <%= expression to return nil, that just results in an empty string, so for that case you can use:
(a = c.detect(&:is_primary)) && a.name
Update: Responding to the first comment, I do have a test case that I didn't post...
class A; attr_accessor :is_primary, :name, :id; end
t = [A.new, A.new, A.new, (a = A.new; a.name = 'xyz'; a.is_primary = true; a)]
puts (a = t.detect(&:is_primary)) && a.name
puts ((a = [].detect(&:is_primary)) && a.name).to_s
Complementing #DigitalRoss, you can also write:
collection.detect(&:is_primary).try(:name) || "default_if_no_element_or_name"
(well, to be honest I prefer Ick's maybe over Rails' try: c.detect(&:is_primary).maybe.name)
Side note: IMHO a flag that can only be active for a row it's not such a good idea. You may have inconsistent states with more than one being active and you'll have worry about it when updating (transactions, and so on). Try to store the PK reference somewhere else (a parent model? a state model?).
I want to do this in 1 line of code if possible. I am trying to slim up this one line for erb output in rails. Later in the page i'll output them all.
No need for one-liners (funny since I just wrote one): move the code to yous models or helpers as appropriate and keep your views pristine.