here are my models looks like so I can address properly my issue
class Product
has_paper_trail
belongs_to :category
end
On my HTML side, I need to load all the logs using the PaperTrial versions. like this
#product.versions.each |version|
version.changeset.each do |k, v|
- if k.to_s == "category_id"
- old_record = v[0].blank? ? " No Record " : Category.find(v[0].to_i).name
- new_record = v[1].blank? ? " No Record " : Category.find(v[1].to_i).name
= "Category" + " From: " + "#{old_record} " + " To: " + "#{new_record}"
in my HTML looks fine but. there is a scenario. that category will be deleted. and I will get an error in this view. because of my "Category.find". the find method cant find the Category that already deleted.
is there a way to store the name of the category and not the ID. so I can get rid of using "find"
or there is a better way to implement these things?
I'd recommend adding category_name attribute to your product model for caching.
# migration
rails g migration AddCategoryNameToProducts category_name
# Product model
before_validation :cache_category_name
def cache_category_name
self.category_name = category&.name if category_name != category&.name
end
But if you had already gone production, you must fill in the data first. And you are not able to fill data, that is already deleted.
# console or migration
Category.find_each(&:save!)
This scenario preserves the deleted category name, additionally it will be much more efficient than a lot of Category.find.
Or you can do some kind of soft-delete as others suggested.
Related
During development, structure of column has been changed, so it's needed to adopt old users data to new format in production. It looks like issue that can be solved by migration. The problem is, I'm not an experienced ruby specialist, so it would be great to have advice how to implement it.
To make things clear, I'll give an example of what happened in my project.
There is table users. This table contains next columns,
id
user_type
description
description here is just JSON string that looks like that in old implementation,
first_name
last_name
address
After changes, instead of first_name and last_name we have full_name, only for users with type 'customer'.
So, how can I migrate my old data to new format? Thanks.
Your respective model User must have following,
serialize :description, Hash
Try to write rake in below path,
lib/tasks/update_users.rake
namespace :update_users do
desc 'Update description for full name for all user'
task update_description: :environment do
User.all.each do |user|
user.description[:full_name] = user.description.delete(:first_name) + ' ' + user.description.delete(:last_name)
user.save(validate: false)
end
end
end
And run rake as, rake update_users:update_description
Perhaps you can run code through rails console,
User.all.each do |user|
user.description[:full_name] = user.description.delete(:first_name) + ' ' + user.description.delete(:last_name)
user.save(validate: false)
end
I have a rails app. I have a table User and a column Number which is a string. Some users saved their phone number with spaces (for example 1234 1234) and now I want to remove the space from their phone numbers.
I tried this but it didn't work:
space = " "
phones = User.where("number like ?", "%#{space}%").pluck(:number)
phones.each do |phone|
phone = phone.gsub(/\s+/, "")
phone.save
end
I got the error NoMethodError: undefined method 'save' How can I do this properly?
You need to have the user object to save it. Read inline comments below
space = " "
users = User.where("number like ?", "%#{space}%") # collect users with number having space character here.
# then iterate on those users
users.each do |user|
user.number = user.number.gsub(/\s+/, "") # notice here, changing the phone number of that user
user.save # and saving that user with the updated `number`
end
You pluck data from User table. Thus, phones variable contains a number array not USER objects. You can't use save on a array element. That's why the error occurs.
You can do the following:
space = " "
phones = User.where("number like ?", "%#{space}%")
phones.each do |phone|
phone.number = phone.number.gsub(/\s+/, "")
phone.save
end
The way you could do is create a rake task to update the existing records on the system.
namespace :update do
desc 'Strip space from existing numbers from Users'
task(:number => ::environment) do
space = ' '
numbers_with_space = User.where("number like ?", "%#{space}%")
numbers_with_space.each do |a|
a.number = a.number.gsub!(/\s+/, '')
a.save(validate: false) # You would like to use
# validate false in order
# to stop other validation from updating the record.
end
end
Then execute the rake task.
bundle exec rake update:number
Another way to handle this beforehand can be through reformatting number during validation. This way you'll not need to run the rake task or code to reformat and save when new data are entered in app.
class User < ApplicationRecord
before_validation :reformat_number, on: [:create, :update]
private
def reformat_number
self.number.gsub!(/\s+/, '')
end
end
I'm trying to track changes on a method just like we are tracking changes on record attributes using the Active Model Dirty.
At the moment I'm using this method to check changes to a set of attributes.
def check_updated_attributes
watch_attrs = ["brand_id", "name", "price", "default_price_tag_id", "terminal_usp", "primary_offer_id", "secondary_offer_id"]
if (self.changed & watch_attrs).any?
self.tag_updated_at = Time.now
end
end
However the attribute price is not a normal attribute with a column but a method defined in the model that combines two different attributes.
This is the method:
def price
if manual_price
price = manual_price
else
price = round_99(base_price)
end
price.to_f
end
Is there a way to track changes on this price method? or does this only work on normal attributes?
Edit: Base price method:
def base_price(rate = Setting.base_margin, mva = Setting.mva)
(cost_price_map / (1 - rate.to_f)) * ( 1 + mva.to_f)
end
cost_price and manual_price are attributes with columns it the terminal table.
Ok, solved it.
I had to create a custom method named price_changed? to check if the price had changed.
def price_changed?
if manual_price
manual_price_changed?
elsif cost_price_map_changed?
round_99(base_price) != round_99(base_price(cost_price = read_attribute(:cost_price_map)))
else
false
end
end
This solved the problem, although not a pretty solution if you have many custom attributes.
I am attempting to generate a fragment cache (using a Dalli/Memcached store) however the key is being generated with "#" as part of the key, so Rails doesn't seem to be recognizing that there is a cache value and is hitting the database.
My cache key in the view looks like this:
cache([#jobs, "index"]) do
The controller has:
#jobs = #current_tenant.active_jobs
With the actual Active Record query like this:
def active_jobs
self.jobs.where("published = ? and expiration_date >= ?", true, Date.today).order("(featured and created_at > now() - interval '" + self.pinned_time_limit.to_s + " days') desc nulls last, created_at desc")
end
Looking at the rails server, I see the cache read, but the SQL Query still runs:
Cache read: views/#<ActiveRecord::Relation:0x007fbabef9cd58>/1-index
Read fragment views/#<ActiveRecord::Relation:0x007fbabef9cd58>/1-index (1.0ms)
(0.6ms) SELECT COUNT(*) FROM "jobs" WHERE "jobs"."tenant_id" = 1 AND (published = 't' and expiration_date >= '2013-03-03')
Job Load (1.2ms) SELECT "jobs".* FROM "jobs" WHERE "jobs"."tenant_id" = 1 AND (published = 't' and expiration_date >= '2013-03-03') ORDER BY (featured and created_at > now() - interval '7 days') desc nulls last, created_at desc
Any ideas as to what I might be doing wrong? I'm sure it has to do w/ the key generation and ActiveRecord::Relation, but i'm not sure how.
Background:
The problem is that the string representation of the relation is different each time your code is run:
|This changes|
views/#<ActiveRecord::Relation:0x007fbabef9cd58>/...
So you get a different cache key each time.
Besides that it is not possible to get rid of database queries completely. (Your own answer is the best one can do)
Solution:
To generate a valid key, instead of this
cache([#jobs, "index"])
do this:
cache([#jobs.to_a, "index"])
This queries the database and builds an array of the models, from which the cache_key is retrieved.
PS: I could swear using relations worked in previous versions of Rails...
We've been doing exactly what you're mentioning in production for about a year. I extracted it into a gem a few months ago:
https://github.com/cmer/scope_cache_key
Basically, it allows you to use a scope as part of your cache key. There are significant performance benefits to doing so since you can now cache a page containing multiple records in a single cache element rather than looping each element in the scope and retrieving caches individually. I feel that combining this with with the standard "Russian Doll Caching" principles is optimal.
I have had similar problems, I have not been able to successfully pass relations to the cache function and your #jobs variable is a relation.
I coded up a solution for cache keys that deals with this issue along with some others that I was having. It basically involves generating a cache key by iterating through the relation.
A full write up is on my site here.
http://mark.stratmann.me/content_items/rails-caching-strategy-using-key-based-approach
In summary I added a get_cache_keys function to ActiveRecord::Base
module CacheKeys
extend ActiveSupport::Concern
# Instance Methods
def get_cache_key(prefix=nil)
cache_key = []
cache_key << prefix if prefix
cache_key << self
self.class.get_cache_key_children.each do |child|
if child.macro == :has_many
self.send(child.name).all.each do |child_record|
cache_key << child_record.get_cache_key
end
end
if child.macro == :belongs_to
cache_key << self.send(child.name).get_cache_key
end
end
return cache_key.flatten
end
# Class Methods
module ClassMethods
def cache_key_children(*args)
#v_cache_key_children = []
# validate the children
args.each do |child|
#is it an association
association = reflect_on_association(child)
if association == nil
raise "#{child} is not an association!"
end
#v_cache_key_children << association
end
end
def get_cache_key_children
return #v_cache_key_children ||= []
end
end
end
# include the extension
ActiveRecord::Base.send(:include, CacheKeys)
I can now create cache fragments by doing
cache(#model.get_cache_key(['textlabel'])) do
I've done something like Hopsoft, but it uses the method in the Rails Guide as a template. I've used the MD5 digest to distinguish between relations (so User.active.cache_key can be differentiated from User.deactivated.cache_key), and used the count and max updated_at to auto-expire the cache on updates to the relation.
require "digest/md5"
module RelationCacheKey
def cache_key
model_identifier = name.underscore.pluralize
relation_identifier = Digest::MD5.hexdigest(to_sql.downcase)
max_updated_at = maximum(:updated_at).try(:utc).try(:to_s, :number)
"#{model_identifier}/#{relation_identifier}-#{count}-#{max_updated_at}"
end
end
ActiveRecord::Relation.send :include, RelationCacheKey
While I marked #mark-stratmann 's response as correct I actually resolved this by simplifying the implementation. I added touch: true to my model relationship declaration:
belongs_to :tenant, touch: true
and then set the cache key based on the tenant (with a required query param as well):
<% cache([#current_tenant, params[:query], "#{#current_tenant.id}-index"]) do %>
That way if a new Job is added, it touches the Tenant cache as well. Not sure if this is the best route, but it works and seems pretty simple.
Im using this code:
class ActiveRecord::Base
def self.cache_key
pluck("concat_ws('/', '#{table_name}', group_concat(#{table_name}.id), date_format(max(#{table_name}.updated_at), '%Y%m%d%H%i%s'))").first
end
def self.updated_at
maximum(:updated_at)
end
end
maybe this can help you out
https://github.com/casiodk/class_cacher , it generates a cache_key from the Model itself, but maybe you can use some of the principles in the codebase
As a starting point you could try something like this:
def self.cache_key
["#{model_name.cache_key}-all",
"#{count}-#{updated_at.utc.to_s(cache_timestamp_format) rescue 'empty'}"
] * '/'
end
def self.updated_at
maximum :updated_at
end
I'm having normalized database where multiple models relate to the same other model, think of clients, locations, etc. all having addresses by means of a street_id.
With this solution you can generate cache_keys based on scope, e.g.
cache [#client, #client.locations] do
# ...
end
cache [#client, #client.locations.active, 'active'] do
# ...
end
and I could simply modify self.updated from above to also include associated objects (because has_many does not support "touch", so if I updated the street, it won't be seen by the cache otherwise):
belongs_to :street
def cache_key
[street.cache_key, super] * '/'
end
# ...
def self.updated_at
[maximum(:updated_at),
joins(:street).maximum('streets.updated_at')
].max
end
As long as you don't "undelete" records and use touch in belongs_to, you should be alright with the assumption that a cache key made of count and max updated_at is sufficient.
I'm using a simple patch on ActiveRecord::Relation to generate cache keys for relations.
require "digest/md5"
module RelationCacheKey
def cache_key
Digest::MD5.hexdigest to_sql.downcase
end
end
ActiveRecord::Relation.send :include, RelationCacheKey
I have a column named updated_at in postgres. I'm trying to have the db set the time by default. But Rails still executes the query updated_at=NULL. But postgres will only set the timestamp by default when updated_at is not in the query at all.
How do I have Rails exclude a column?
You can disable this behaviour by setting ActiveRecord::Base class variable
record_timestamps to false.
In config/environment.rb, Rails::Initializer.run block :
config.active_record.record_timestamps = false
(if this doesn't work, try instead ActiveRecord::Base.record_timestamps = false at the end of the file)
If you want to set only for a given model :
class Foo < ActiveRecord::Base
self.record_timestamps = false
end
Credit to Jean-François at http://www.ruby-forum.com/topic/72569
I've been running into a similar issue in Rails 2.2.2. As of this version there is an attr_readonly method in ActiveRecord but create doesn't respect it, only update. I don't know if this has been changed in the latest version. I overrode the create method to force is to respect this setting.
def create
if self.id.nil? && connection.prefetch_primary_key?(self.class.table_name)
self.id = connection.next_sequence_value(self.class.sequence_name)
end
quoted_attributes = attributes_with_quotes(true, false)
statement = if quoted_attributes.empty?
connection.empty_insert_statement(self.class.table_name)
else
"INSERT INTO #{self.class.quoted_table_name} " +
"(#{quoted_attributes.keys.join(', ')}) " +
"VALUES(#{quoted_attributes.values.join(', ')})"
end
self.id = connection.insert(statement, "#{self.class.name} Create",
self.class.primary_key, self.id, self.class.sequence_name)
#new_record = false
id
end
The change is just to pass false as the second parameter to attributes_with_quotes, and use quoted_attributes.keys for the column names when building the SQL. This has worked for me. The downside is that by overriding this you will lose before_create and after_create callbacks, and I haven't had time to dig into it enough to figure out why. If anyone cares to expand/improve on this solution or offer a better solution, I'm all ears.