Using index_by in this way creates a Hash keyed to the abbr value. If abbr is non- unique and there are multiple records with the same value, this gets slightly 19 Feb 2019 A partial index covers just a subset of a table's data. It is an index with a WHERE clause. The idea is to increase the efficiency of the index by Flowdock - Team Inbox With Chat. Flowdock is a collaboration tool for technical teams. Version control, project management, deployments and your group chat in one place. Upgraded app to Rails 5 using the index method. The issue is that it is not incrementing to the next ActiveRecord collection record. The below code below use to work in Rails 4.0. Tried with index_by. def next_question index = campaign.quiz_questions.index self campaign.quiz_questions[index + 1] end Debugger The other usage we found for index_by was to utilize the fact that index_by overwrites the value instead of appending (which group_by does). We had a list of scores and wanted to group them together. The group_by method could handle that case; however, we only wanted to keep track of the highest score per group.
If a block is given instead of an argument, returns the index of the first object for which the block returns true. Returns nil if no match is found. See also Array#rindex. An Enumerator is returned if neither a block nor argument is given. Register or to add new notes. gaurish wants to merge 2 commits into rails: master from unknown repository +72 −0 Conversation 5 Commits 2 Checks 0 Files changed 6 Conversation. Copy link Quote reply Contributor gaurish commented Sep 3, 2017. Fixes #27110. Initial POC to gather feedback & check if the approach is good.
Rails4で確認。オブジェクトが存在する場合は取得、なければ作成、ということがしたい場合にfind_or_create_byが使うと便利です。ですが、find_or_create_byだと新規作成の場合のみ特定の処理をさせたい、といった場合にnew_recordなのかどうか区別がつきません。 The other usage we found for index_by was to utilize the fact that index_by overwrites the value instead of appending (which group_by does). We had a list of scores and wanted to group them together. The group_by method could handle that case; however, we only wanted to keep track of the highest score per group. Los Angeles Railway/Los Angeles Transit Lines. Louisville & Nashville. Magma Arizona/San Manuel Copper How to create a migration to remove an index only if it exists, rather than throwing an exception if it doesn't? There is also index_name_exists?(table_name, index_name) method which let's you check for an index by it's name. It's helpful for checking for existence of multi-column indexes. Will removing a column with a Rails migration gaurish wants to merge 2 commits into rails: master from unknown repository +72 −0 Conversation 5 Commits 2 Checks 0 Files changed 6 Conversation. Copy link Quote reply Contributor gaurish commented Sep 3, 2017. Fixes #27110. Initial POC to gather feedback & check if the approach is good. Ruby on Rails. Contribute to rails/rails development by creating an account on GitHub. index_by acts like group_by but only maps a single record, instead of an array, keeping the last match only. It's usually used in places where you shouldn't have more than a single match for each key. Would you consider its inclusion to core Enumerable module?
The other usage we found for index_by was to utilize the fact that index_by overwrites the value instead of appending (which group_by does). We had a list of scores and wanted to group them together. The group_by method could handle that case; however, we only wanted to keep track of the highest score per group. Los Angeles Railway/Los Angeles Transit Lines. Louisville & Nashville. Magma Arizona/San Manuel Copper How to create a migration to remove an index only if it exists, rather than throwing an exception if it doesn't? There is also index_name_exists?(table_name, index_name) method which let's you check for an index by it's name. It's helpful for checking for existence of multi-column indexes. Will removing a column with a Rails migration gaurish wants to merge 2 commits into rails: master from unknown repository +72 −0 Conversation 5 Commits 2 Checks 0 Files changed 6 Conversation. Copy link Quote reply Contributor gaurish commented Sep 3, 2017. Fixes #27110. Initial POC to gather feedback & check if the approach is good. Ruby on Rails. Contribute to rails/rails development by creating an account on GitHub.
#index_by ⇒ Object. Convert an enumerable to a hash. #many? ⇒ Boolean. Returns true if the enumerable has more than 1 element. #sum(identity = 0, &block) rails/activesupport/lib/active_support/core_ext/enumerable.rb to_enum(: index_by) { size if respond_to? def index_with(default = INDEX_WITH_DEFAULT). 10.4 index_by. The method index_by generates a hash with the elements of an enumerable indexed by some key. It iterates through