I am trying to find a specific value inside an array. The array is composed from data in MySQL database and looks like:
info = [#<Info1: bla, Info2: blo>,#<Info1: bli, Info2, Ble>]
Now I want to get every Info1's value from it, but I do not know how.
The array was formed by calling
info = Info.find(:all)
Can anyone help me?
I am using Rails 2.2.2 (don't ask, can't do anything about it) and Ruby 1.8.
Edit: More details
Info is a database, where Info1 and info 2 are the columns. Calling it with info = Info.find(:all) returns the array above.
What I have tried so far involves trying to go through the array with each, but so far no luck.
Most of what I have tried like
a.grep(/^info1/)
and
info.select(|i| i.name == "info1")
all return empty arrays
Edit
Nevermind, I found the answer. I was thinking too weird. The answer is
info.each do |object|
puts object.info2
end
What's your selection criteria? You can do something like
info.select{|i| i.name == 'hello' }
and you will get all the Info objects with name = 'hello'.
But I would prefer to change the query, if you can, to filter them in the database query directly.
Related
I’m using NestJS with TypeORM, database is MySQL, and I’d like to filter multiple parameters that can be passed in.
The frontend has a list of products and filters are applied as query params sent to NestJS, filtering works for a single param eg api.example.com?manufacturer=Acer but how would I filter an Array eg api.example.com?manufacturer=Acer,Toshiba,Asus.
I tried quite a few things in TypeORM, currently using the QueryBuilder to build the array with an if statement if the filter exists if so I’m doing something like a where statement.
.andWhere(manufacturer = filterOne, {filterOne: *manufacturers from the query param*})
But yeah just can’t hack something together, tried a couple of things, above is a rough example, did try methods that TypeORM had as an example on filtering arrays but it seemed like it was more for an array of integers only? Regardless, I’m open to any methods that allow for the end result of filtering the example I provided, cheers and thanks again!
You have to use IN to get all data where manufacturer equal the data came from the query, first, you have to convert the query to an array:
var manufacturerParam = filterOne.split(",");
then add it to your query:
.andWhere(manufacturer IN (:filter)", { filter: manufacturerParam })
I have to update a lot of data to mysql (~100Mio records!). Some records already exists, some have to be created. I also have to create some nested resources for each record.
I know the activerecord-import gem but as far as i know it can't handle nested records (or only with ugly workarounds). The issue is that I dont know the ID's for all nested records before they are created - and creating them in single queries takes time.
So lets say there is a model called Post and can have many Comments. My current code looks like this:
Post.transaction do
import_posts.each do |import_post|
post = Post.find_or_initialize_by(somevalue: import_post['somevalue']
post.text = import_post['text']
import_post['comments'].each do |import_comment|
comment = post.comments.find_or_initialize_by(someothervalue: import_comment['someothervalue'])
comment.text = import_comment['text']
end
post.save(validate: false) #Dont need validation - saves some time
end
end
This is just an example and it works but its far away from 'damn fast'. Are there any ideas how to speed up the data upload? Am I totally wrong?
Im working with Rails5 and ruby 2.4.
Thanks in advance!
I have a model called lists, which has a column called item_ids. item_ids is a JSON column (MySQL) and the column contains array of UUIDs, each referring to one item.
Now when someone creates a new list, I need to search whether there is an existing list with same set of UUIDs, and I want to do this search using query itself for faster response. Also use ActiveRecord querying as much as possible.
How do i achieve this?
item_ids = ["11E85378-CFE8-39F8-89DC-7086913CFD4B", "11E85354-304C-0664-9E81-0A281BE2CA42"]
v = List.new(item_ids: item_ids)
v.save!
Now, how do I check whether a list exists which has item ids exactly matches with that mentioned in query ? Following wont work.
list_count = List.where(item_ids: item_ids).count
Edit 1
List.where("JSON_CONTAINS(item_ids, ?) ", item_ids.to_json).count
This statement works, but it counts even if only one of the item matches. Looking for exact number of items.
Edit 2
List.where("JSON_CONTAINS( item_ids, ?) and JSON_LENGTH(item_ids) = ?", item_ids.to_json, item_ids.size).count
Looks like this is working
You can implement a has many relation between lists and items and then access like this.
List.includes(:item).where('items.id in (?)',item_ids)
To implement has_many relation:
http://guides.rubyonrails.org/association_basics.html#the-has-many-through-association
I've got records in my MySQL projects database that have several boolean flags to help me sort the data. I have 3 categories planning, landscape, and environmental and 4 classes (or subcategories) for each category; industrial, government, education, residential.
My goal is to use ColdFusion to create and store the project_id numbers in an array of some kind that will basically have the projects sorted by category and class. That way I can grab just the industrial projects in the planning category and construct a link to that project.
So, the first position in the array would be planning and inside that first position would be the 4 classes, then, within that would be all of the project_id numbers that returned true for those particular criteria.
The logic I'm looking to create goes like this...
Loop over the query result, if planning = true and industrial = true, place the project id # into the planning array inside the industrial array.
How can I use <cfloop> to loop over the list of project records, recognize the category and class flags and construct a clean and usable dataset? Can this be handles in the query in some way?
Figure out the desired data structure
look at your existing data structure
figure out the algorithm to translate from one to the other
You may cfloop the query, and use a large cfswitch (or large set of if-then-else) to figure out how you want to store the id in your desired data structure. Or if you can map the class/category name as a struct key, then it might be easier.
Or you may use cfoutput group="" if it helps (cfloop group="" is available on in CF10+)
Finally, maybe you don't even need the data structure, just use Query of Queries wherever you need.
You may be able to utilize the Underscore.cfc library for this. For example, you could use the filter function to extract an array of structs representing the query rows you want:
planningArray = _.filter(queryResult, function(row){
return (row.planning == true && row.industrial == true);
});
I have the following query
#initial_matches = Listing.find_by_sql(["SELECT * FROM listings WHERE industry = ?", current_user.industry])
Is there a way I can run another SQL query on the selection from the above query using a each do? I want to run geokit calculations to eliminate certain listings that are outside of a specified distance...
Your question is slightly confusing. Do you want to use each..do (ruby) to do the filtering. Or do you want to use a sql query. Here is how you can let the ruby process do the filtering
refined list = #initial_matches.map { |listing|
listing.out_of_bounds? ? nil : listing
}.comact
If you wanted to use sql you could simply add additional sql (maybe a sub-select) it into your Listing.find_by_sql call.
If you want to do as you say in your comment.
WHERE location1.distance_from(location2, :units=>:miles)
You are mixing ruby (location1.distance_from(location2, :units=>:miles)) and sql (WHERE X > 50). This is difficult, but not impossible.
However, if you have to do the distance calculation in ruby already, why not do the filtering there as well. So in the spirit of my first example.
listing2 = some_location_to_filter_by
#refined_list = #initial_matches.map { |listing|
listing.distance_from(listing2) > 50 ? nil : listing
}.compact
This will iterate over all listings, keeping only those that are further than 50 from some predetermined listing.
EDIT: If this logic is done in the controller you need to assign to #refined_list instead of refined_list since only controller instance variables (as opposed to local ones) are accessible to the view.
In short, no. This is because after the initial query, you are not left with a relational table or view, you are left with an array of activerecord objects. So any processing to be done after the initial query has to be in the format of ruby and activerecord, not sql.