Class: ActiveRecord::Relation
Relationships & Source Files | |
Namespace Children | |
Modules:
| |
Extension / Inclusion / Inheritance Descendants | |
Subclasses:
ActiveRecord::AssociationRelation, ActiveRecord::DisableJoinsAssociationRelation, Associations::CollectionProxy
|
|
Super Chains via Extension / Inclusion / Inheritance | |
Instance Chain:
|
|
Inherits: | Object |
Defined in: | activerecord/lib/active_record/relation.rb, activerecord/lib/active_record/relation/from_clause.rb, activerecord/lib/active_record/relation/merger.rb, activerecord/lib/active_record/relation/query_attribute.rb, activerecord/lib/active_record/relation/record_fetch_warning.rb, activerecord/lib/active_record/relation/where_clause.rb |
Constant Summary
-
CLAUSE_METHODS =
# File 'activerecord/lib/active_record/relation.rb', line 14[:where, :having, :from]
-
INVALID_METHODS_FOR_DELETE_ALL =
# File 'activerecord/lib/active_record/relation.rb', line 15[:distinct, :with]
-
MULTI_VALUE_METHODS =
# File 'activerecord/lib/active_record/relation.rb', line 6[:includes, :eager_load, :preload, :select, :group, :order, :joins, :left_outer_joins, :references, :extending, :unscope, :optimizer_hints, :annotate, :with]
-
SINGLE_VALUE_METHODS =
# File 'activerecord/lib/active_record/relation.rb', line 11[:limit, :offset, :lock, :readonly, :reordering, :strict_loading, :reverse_order, :distinct, :create_with, :skip_query_cache]
-
VALUE_METHODS =
# File 'activerecord/lib/active_record/relation.rb', line 17MULTI_VALUE_METHODS + SINGLE_VALUE_METHODS + CLAUSE_METHODS
Batches
- Included
DEFAULT_ORDER, ORDER_IGNORE_MESSAGE
QueryMethods
- Included
FROZEN_EMPTY_ARRAY, FROZEN_EMPTY_HASH, VALID_UNSCOPING_VALUES
FinderMethods
- Included
Class Method Summary
Instance Attribute Summary
-
#blank? ⇒ Boolean
readonly
Returns true if relation is blank.
-
#eager_loading? ⇒ Boolean
readonly
Returns true if relation needs eager loading.
-
#empty? ⇒ Boolean
readonly
Returns true if there are no records.
- #klass (also: #model) readonly
-
#loaded?
readonly
Alias for #loaded.
-
#many? ⇒ Boolean
readonly
Returns true if there is more than one record.
-
#model
readonly
Alias for #klass.
- #predicate_builder readonly
-
#scheduled? ⇒ Boolean
readonly
Returns
true
if the relation was scheduled on the background thread pool. - #skip_preloading_value rw
- #table readonly
::Enumerable
- Included
#many? | Returns |
Instance Method Summary
-
#==(other)
Compares two relations for equality.
-
#any?(*args) ⇒ Boolean
Returns true if there are any records.
-
#build(attributes = nil, &block)
Alias for #new.
-
#cache_key(timestamp_column = "updated_at")
Returns a stable cache key that can be used to identify this query.
-
#cache_key_with_version
Returns a cache key along with the version.
-
#cache_version(timestamp_column = :updated_at)
Returns a cache version that can be used together with the cache key to form a recyclable caching scheme.
-
#create(attributes = nil, &block)
Tries to create a new record with the same scoped attributes defined in the relation.
- #create!(attributes = nil, &block)
-
#create_or_find_by(attributes, &block)
Attempts to create a record with the given attributes in a table that has a unique database constraint on one or several of its columns.
-
#create_or_find_by!(attributes, &block)
Like #create_or_find_by, but calls create! so an exception is raised if the created record is invalid.
-
#delete_all
Deletes the records without instantiating the records first, and hence not calling the #destroy method nor invoking callbacks.
-
#delete_by(*args)
Finds and deletes all records matching the specified conditions.
-
#destroy_all
Destroys the records by instantiating each record and calling its #destroy method.
-
#destroy_by(*args)
Finds and destroys all records matching the specified conditions.
-
#encode_with(coder)
Serializes the relation objects
::Array
. -
#explain(*options)
Runs EXPLAIN on the query or queries triggered by this relation and returns the result as a string.
-
#find_or_create_by(attributes, &block)
Finds the first record with the given attributes, or creates a record with the attributes if one is not found:
-
#find_or_create_by!(attributes, &block)
Like #find_or_create_by, but calls create! so an exception is raised if the created record is invalid.
-
#find_or_initialize_by(attributes, &block)
Like #find_or_create_by, but calls
new
instead of create. - #initialize_copy(other)
- #inspect
-
#joined_includes_values
Joins that are also marked for preloading.
-
#load(&block)
Causes the records to be loaded from the database if they have not been loaded already.
-
#load_async
Schedule the query to be performed from a background thread pool.
- #loaded (also: #loaded?) readonly
- #locked?
-
#new(attributes = nil, &block)
(also: #build)
Initializes new record from relation while maintaining the current scope.
-
#none?(*args) ⇒ Boolean
Returns true if there are no records.
-
#one?(*args) ⇒ Boolean
Returns true if there is exactly one record.
- #pretty_print(pp)
-
#reload
Forces reloading of relation.
- #reset
- #scope_for_create
-
#scoping(all_queries: nil, &block)
Scope all queries to the current scope.
-
#size
Returns size of the records.
-
#to_a
Alias for #to_ary.
-
#to_ary
(also: #to_a)
Converts relation objects to
::Array
. -
#to_sql
Returns sql statement for the relation.
-
#touch_all(*names, time: nil)
Touches all records in the current relation, setting the
updated_at+/+updated_on
attributes to the current time or the time specified. -
#update_all(updates)
Updates all records in the current relation with details given.
-
#update_counters(counters)
Updates the counters of the records in the current relation.
- #values
FinderMethods
- Included
#exists? | Returns true if a record exists in the table that matches the |
#fifth | Find the fifth record. |
#fifth! | Same as |
#find | Find by id - This can either be a specific id (ID), a list of ids (ID, ID, ID), or an array of ids ([ID, ID, ID]). |
#find_by | Finds the first record matching the specified conditions. |
#find_by! | Like |
#find_sole_by | Finds the sole matching record. |
#first | Find the first record (or first N records if a parameter is supplied). |
#first! | Same as |
#forty_two | Find the forty-second record. |
#forty_two! | Same as |
#fourth | Find the fourth record. |
#fourth! | Same as |
#include? | Returns true if the relation contains the given record or false otherwise. |
#last | Find the last record (or last N records if a parameter is supplied). |
#last! | Same as |
#member? | Alias for FinderMethods#include?. |
#second | Find the second record. |
#second! | Same as |
#second_to_last | Find the second-to-last record. |
#second_to_last! | Same as |
#sole | Finds the sole matching record. |
#take | Gives a record (or N records if a parameter is supplied) without any implied order. |
#take! | Same as |
#third | Find the third record. |
#third! | Same as |
#third_to_last | Find the third-to-last record. |
#third_to_last! | Same as |
Calculations
- Included
#async_average | Same as |
#async_count | Same as |
#async_ids | Same as |
#async_maximum | Same as |
#async_minimum | Same as |
#async_pick | Same as |
#async_pluck | Same as |
#async_sum | Same as |
#average | Calculates the average value on a given column. |
#calculate | This calculates aggregate values in the given column. |
#count | Count the records. |
#ids | Returns the base model’s ID’s for the relation using the table’s primary key. |
#maximum | Calculates the maximum value on a given column. |
#minimum | Calculates the minimum value on a given column. |
#pick | Pick the value(s) from the named column(s) in the current relation. |
#pluck | Use |
#sum | Calculates the sum of values on a given column. |
SpawnMethods
- Included
#except | Removes from the query the condition(s) specified in |
#merge | Merges in the conditions from |
#only | Removes any condition from the query other than the one(s) specified in |
QueryMethods
- Included
#and | Returns a new relation, which is the logical intersection of this relation and the one passed as an argument. |
#annotate | Adds an SQL comment to queries generated from this relation. |
#create_with | Sets attributes to be used when creating new records from a relation object. |
#distinct | Specifies whether the records should be unique or not. |
#eager_load | Specify associations |
#excluding | Excludes the specified record (or collection of records) from the resulting relation. |
#extending | Used to extend a scope with additional methods, either through a module or through a block provided. |
#extensions, | |
#extract_associated | Extracts a named |
#from | Specifies the table from which the records will be fetched. |
#group | Allows to specify a group attribute: |
#having | Allows to specify a HAVING clause. |
#in_order_of | Allows to specify an order by a specific set of values. |
#includes | Specify associations |
#invert_where | Allows you to invert an entire where clause instead of manually applying conditions. |
#joins | Performs JOINs on |
#left_joins | Alias for QueryMethods#left_outer_joins. |
#left_outer_joins | Performs LEFT OUTER JOINs on |
#limit | Specifies a limit for the number of records to retrieve. |
#lock | Specifies locking settings (default to |
#none | Returns a chainable relation with zero records. |
#offset | Specifies the number of rows to skip before returning rows. |
#optimizer_hints | Specify optimizer hints to be used in the SELECT statement. |
#or | Returns a new relation, which is the logical union of this relation and the one passed as an argument. |
#order | Applies an |
#preload | Specify associations |
#readonly | Mark a relation as readonly. |
#references | Use to indicate that the given |
#regroup | Allows you to change a previously set group statement. |
#reorder | Replaces any existing order defined on the relation with the specified order. |
#reselect | Allows you to change a previously set select statement. |
#reverse_order | Reverse the existing order clause on the relation. |
#rewhere | Allows you to change a previously set where condition for a given attribute, instead of appending to that condition. |
#select | Works in two unique ways. |
#strict_loading | Sets the returned relation to strict_loading mode. |
#structurally_compatible? | Checks whether the given relation is structurally compatible with this relation, to determine if it’s possible to use the |
#uniq! | Deduplicate multiple values. |
#unscope | Removes an unwanted relation that is already defined on a chain of relations. |
#where | Returns a new relation, which is the result of filtering the current relation according to the conditions in the arguments. |
#with | Add a Common Table Expression (CTE) that you can then reference within another SELECT statement. |
#without | Alias for QueryMethods#excluding. |
Batches
- Included
#find_each | Looping through a collection of records from the database (using the Scoping::Named::ClassMethods#all method, for example) is very inefficient since it will try to instantiate all the objects at once. |
#find_in_batches | Yields each batch of records that was found by the find options as an array. |
#in_batches | Yields |
::Enumerable
- Included
#compact_blank | Returns a new |
#exclude? | The negative of the |
#excluding | Returns a copy of the enumerable excluding the specified elements. |
#in_order_of | Returns a new |
#including | Returns a new array that includes the passed elements. |
#index_by | Convert an enumerable to a hash, using the block result as the key and the element as the value. |
#index_with | Convert an enumerable to a hash, using the element as the key and the block result as the value. |
#maximum | Calculates the maximum from the extracted elements. |
#minimum | Calculates the minimum from the extracted elements. |
#pick | Extract the given key from the first element in the enumerable. |
#pluck | Extract the given key from each element in the enumerable. |
#sole | Returns the sole item in the enumerable. |
#without | Alias for Enumerable#excluding. |
Constructor Details
.new(klass, table: klass.arel_table, predicate_builder: klass.predicate_builder, values: {}) ⇒ Relation
# File 'activerecord/lib/active_record/relation.rb', line 28
def initialize(klass, table: klass.arel_table, predicate_builder: klass.predicate_builder, values: {}) @klass = klass @table = table @values = values @loaded = false @predicate_builder = predicate_builder @delegate_to_klass = false @future_result = nil @records = nil @async = false @none = false end
Instance Attribute Details
#blank? ⇒ Boolean
(readonly)
Returns true if relation is blank.
# File 'activerecord/lib/active_record/relation.rb', line 844
def blank? records.blank? end
#eager_loading? ⇒ Boolean
(readonly)
Returns true if relation needs eager loading.
# File 'activerecord/lib/active_record/relation.rb', line 808
def eager_loading? @should_eager_load ||= eager_load_values.any? || includes_values.any? && (joined_includes_values.any? || references_eager_loaded_tables?) end
#empty? ⇒ Boolean
(readonly)
Returns true if there are no records.
#klass (readonly) Also known as: #model
[ GitHub ]# File 'activerecord/lib/active_record/relation.rb', line 22
attr_reader :table, :klass, :loaded, :predicate_builder
#loaded? (readonly)
Alias for #loaded.
# File 'activerecord/lib/active_record/relation.rb', line 25
alias :loaded? :loaded
#many? ⇒ Boolean
(readonly)
Returns true if there is more than one record.
#model (readonly)
Alias for #klass.
# File 'activerecord/lib/active_record/relation.rb', line 24
alias :model :klass
#predicate_builder (readonly)
[ GitHub ]
#scheduled? ⇒ Boolean
(readonly)
Returns true
if the relation was scheduled on the background thread pool.
# File 'activerecord/lib/active_record/relation.rb', line 740
def scheduled? !!@future_result end
#skip_preloading_value (rw)
[ GitHub ]# File 'activerecord/lib/active_record/relation.rb', line 23
attr_accessor :skip_preloading_value
#table (readonly)
[ GitHub ]# File 'activerecord/lib/active_record/relation.rb', line 22
attr_reader :table, :klass, :loaded, :predicate_builder
Instance Method Details
#==(other)
Compares two relations for equality.
# File 'activerecord/lib/active_record/relation.rb', line 823
def ==(other) case other when Associations::CollectionProxy, AssociationRelation self == other.records when Relation other.to_sql == to_sql when Array records == other end end
#any?(*args) ⇒ Boolean
Returns true if there are any records.
When a pattern argument is given, this method checks whether elements in the ::Enumerable
match the pattern via the case-equality operator (===
).
posts.any?(Post) # => true or false
# File 'activerecord/lib/active_record/relation.rb', line 312
def any?(*args) return false if @none return super if args.present? || block_given? !empty? end
#build(attributes = nil, &block)
Alias for #new.
# File 'activerecord/lib/active_record/relation.rb', line 77
alias build new
#cache_key(timestamp_column = "updated_at")
Returns a stable cache key that can be used to identify this query. The cache key is built with a fingerprint of the SQL query.
Product.where("name like ?", "%Cosmic Encounter%").cache_key
# => "products/query-1850ab3d302391b85b8693e941286659"
If Base.collection_cache_versioning is turned off, as it was in Rails 6.0 and earlier, the cache key will also include a version.
ActiveRecord::Base.collection_cache_versioning = false
Product.where("name like ?", "%Cosmic Encounter%").cache_key
# => "products/query-1850ab3d302391b85b8693e941286659-1-20150714212553907087000"
You can also pass a custom timestamp column to fetch the timestamp of the last updated record.
Product.where("name like ?", "%Game%").cache_key(:last_reviewed_at)
# File 'activerecord/lib/active_record/relation.rb', line 359
def cache_key( = "updated_at") @cache_keys ||= {} @cache_keys[ ] ||= klass.collection_cache_key(self, ) end
#cache_key_with_version
Returns a cache key along with the version.
# File 'activerecord/lib/active_record/relation.rb', line 438
def cache_key_with_version if version = cache_version "#{cache_key}-#{version}" else cache_key end end
#cache_version(timestamp_column = :updated_at)
Returns a cache version that can be used together with the cache key to form a recyclable caching scheme. The cache version is built with the number of records matching the query, and the timestamp of the last updated record. When a new record comes to match the query, or any of the existing records is updated or deleted, the cache version changes.
If the collection is loaded, the method will iterate through the records to generate the timestamp, otherwise it will trigger one SQL query like:
SELECT COUNT(*), MAX("products"."updated_at") FROM "products" WHERE (name like '%Cosmic Encounter%')
# File 'activerecord/lib/active_record/relation.rb', line 386
def cache_version( = :updated_at) if collection_cache_versioning @cache_versions ||= {} @cache_versions[ ] ||= compute_cache_version( ) end end
#create(attributes = nil, &block)
Tries to create a new record with the same scoped attributes defined in the relation. Returns the initialized object if validation fails.
Expects arguments in the same format as {ActiveRecord::Base.create}.
Examples
users = User.where(name: 'Oscar')
users.create # => #<User id: 3, name: "Oscar", ...>
users.create(name: 'fxn')
users.create # => #<User id: 4, name: "fxn", ...>
users.create { |user| user.name = 'tenderlove' }
# => #<User id: 5, name: "tenderlove", ...>
users.create(name: nil) # validation on name
# => #<User id: nil, name: nil, ...>
#create!(attributes = nil, &block)
Similar to #create, but calls create! on the base class. Raises an exception if a validation error occurs.
Expects arguments in the same format as {ActiveRecord::Base.create!}.
#create_or_find_by(attributes, &block)
Attempts to create a record with the given attributes in a table that has a unique database constraint on one or several of its columns. If a row already exists with one or several of these unique constraints, the exception such an insertion would normally raise is caught, and the existing record with those attributes is found using #find_by!
.
This is similar to #find_or_create_by, but tries to create the record first. As such it is better suited for cases where the record is most likely not to exist yet.
There are several drawbacks to #create_or_find_by
, though:
-
The underlying table must have the relevant columns defined with unique database constraints.
-
A unique constraint violation may be triggered by only one, or at least less than all, of the given attributes. This means that the subsequent #find_by! may fail to find a matching record, which will then raise an ActiveRecord::RecordNotFound exception, rather than a record with the given attributes.
-
While we avoid the race condition between SELECT -> INSERT from #find_or_create_by, we actually have another race condition between INSERT -> SELECT, which can be triggered if a DELETE between those two statements is run by another client. But for most applications, that’s a significantly less likely condition to hit.
-
It relies on exception handling to handle control flow, which may be marginally slower.
-
The primary key may auto-increment on each create, even if it fails. This can accelerate the problem of running out of integers, if the underlying table is still stuck on a primary key of type int (note: All Rails apps since 5.1+ have defaulted to bigint, which is not liable to this problem).
This method will return a record if all given attributes are covered by unique constraints (unless the INSERT -> DELETE -> SELECT race condition is triggered), but if creation was attempted and failed due to validation errors it won’t be persisted, you get what #create returns in such situation.
# File 'activerecord/lib/active_record/relation.rb', line 215
def create_or_find_by(attributes, &block) transaction(requires_new: true) { create(attributes, &block) } rescue ActiveRecord::RecordNotUnique if connection.transaction_open? where(attributes).lock.find_by!(attributes) else find_by!(attributes) end end
#create_or_find_by!(attributes, &block)
Like #create_or_find_by, but calls create! so an exception is raised if the created record is invalid.
# File 'activerecord/lib/active_record/relation.rb', line 228
def create_or_find_by!(attributes, &block) transaction(requires_new: true) { create!(attributes, &block) } rescue ActiveRecord::RecordNotUnique if connection.transaction_open? where(attributes).lock.find_by!(attributes) else find_by!(attributes) end end
#delete_all
Deletes the records without instantiating the records first, and hence not calling the #destroy method nor invoking callbacks. This is a single SQL DELETE statement that goes straight to the database, much more efficient than #destroy_all. Be careful with relations though, in particular :dependent
rules defined on associations are not honored. Returns the number of rows affected.
Post.where(person_id: 5).where(category: ['Something', 'Else']).delete_all
Both calls delete the affected posts all at once with a single DELETE statement. If you need to destroy dependent associations or call your before_*
or after_destroy
callbacks, use the #destroy_all method instead.
If an invalid method is supplied, #delete_all
raises an ActiveRecordError
:
Post.distinct.delete_all
# => ActiveRecord::ActiveRecordError: delete_all doesn't support distinct
# File 'activerecord/lib/active_record/relation.rb', line 651
def delete_all return 0 if @none invalid_methods = INVALID_METHODS_FOR_DELETE_ALL.select do |method| value = @values[method] method == :distinct ? value : value&.any? end if invalid_methods.any? raise ActiveRecordError.new("delete_all doesn't support #{invalid_methods.join(', ')}") end arel = eager_loading? ? apply_join_dependency.arel : build_arel arel.source.left = table group_values_arel_columns = arel_columns(group_values.uniq) having_clause_ast = having_clause.ast unless having_clause.empty? key = if klass.composite_primary_key? primary_key.map { |pk| table[pk] } else table[primary_key] end stmt = arel.compile_delete(key, having_clause_ast, group_values_arel_columns) klass.connection.delete(stmt, "#{klass} Delete All").tap { reset } end
#delete_by(*args)
Finds and deletes all records matching the specified conditions. This is short-hand for relation.where(condition).delete_all
. Returns the number of rows affected.
If no record is found, returns 0
as zero rows were affected.
Person.delete_by(id: 13)
Person.delete_by(name: 'Spartacus', rating: 4)
Person.delete_by("published_at < ?", 2.weeks.ago)
# File 'activerecord/lib/active_record/relation.rb', line 699
def delete_by(*args) where(*args).delete_all end
#destroy_all
Destroys the records by instantiating each record and calling its #destroy method. Each object’s callbacks are executed (including :dependent
association options). Returns the collection of objects that were destroyed; each will be frozen, to reflect that no changes should be made (since they can’t be persisted).
Note: Instantiation, callback execution, and deletion of each record can be time consuming when you’re removing many records at once. It generates at least one SQL DELETE
query per record (or possibly more, to enforce your callbacks). If you want to delete many rows quickly, without concern for their associations or callbacks, use #delete_all instead.
Examples
Person.where(age: 0..18).destroy_all
#destroy_by(*args)
Finds and destroys all records matching the specified conditions. This is short-hand for relation.where(condition).destroy_all
. Returns the collection of objects that were destroyed.
If no record is found, returns empty array.
Person.destroy_by(id: 13)
Person.destroy_by(name: 'Spartacus', rating: 4)
Person.destroy_by("published_at < ?", 2.weeks.ago)
# File 'activerecord/lib/active_record/relation.rb', line 686
def destroy_by(*args) where(*args).destroy_all end
#encode_with(coder)
Serializes the relation objects ::Array
.
# File 'activerecord/lib/active_record/relation.rb', line 269
def encode_with(coder) coder.represent_seq(nil, records) end
#explain(*options)
Runs EXPLAIN on the query or queries triggered by this relation and returns the result as a string. The string is formatted imitating the ones printed by the database shell.
Note that this method actually runs the queries, since the results of some are needed by the next ones when eager loading is going on.
Please see further details in the Active Record Query Interface guide.
# File 'activerecord/lib/active_record/relation.rb', line 253
def explain(* ) exec_explain(collecting_queries_for_explain { exec_queries }, ) end
#find_or_create_by(attributes, &block)
Finds the first record with the given attributes, or creates a record with the attributes if one is not found:
# Find the first user named "Penélope" or create a new one.
User.find_or_create_by(first_name: 'Penélope')
# => #<User id: 1, first_name: "Penélope", last_name: nil>
# Find the first user named "Penélope" or create a new one.
# We already have one so the existing record will be returned.
User.find_or_create_by(first_name: 'Penélope')
# => #<User id: 1, first_name: "Penélope", last_name: nil>
# Find the first user named "Scarlett" or create a new one with
# a particular last name.
User.create_with(last_name: 'Johansson').find_or_create_by(first_name: 'Scarlett')
# => #<User id: 2, first_name: "Scarlett", last_name: "Johansson">
This method accepts a block, which is passed down to #create. The last example above can be alternatively written this way:
# Find the first user named "Scarlett" or create a new one with a
# particular last name.
User.find_or_create_by(first_name: 'Scarlett') do |user|
user.last_name = 'Johansson'
end
# => #<User id: 2, first_name: "Scarlett", last_name: "Johansson">
This method always returns a record, but if creation was attempted and failed due to validation errors it won’t be persisted, you get what #create returns in such situation.
If creation failed because of a unique constraint, this method will assume it encountered a race condition and will try finding the record once more. If somehow the second find still does not find a record because a concurrent DELETE happened, it will then raise an RecordNotFound
exception.
Please note this method is not atomic, it runs first a SELECT, and if there are no results an INSERT is attempted. So if the table doesn’t have a relevant unique constraint it could be the case that you end up with two or more similar records.
# File 'activerecord/lib/active_record/relation.rb', line 175
def find_or_create_by(attributes, &block) find_by(attributes) || create_or_find_by(attributes, &block) end
#find_or_create_by!(attributes, &block)
Like #find_or_create_by, but calls create! so an exception is raised if the created record is invalid.
# File 'activerecord/lib/active_record/relation.rb', line 182
def find_or_create_by!(attributes, &block) find_by(attributes) || create_or_find_by!(attributes, &block) end
#find_or_initialize_by(attributes, &block)
Like #find_or_create_by, but calls new
instead of create.
# File 'activerecord/lib/active_record/relation.rb', line 240
def find_or_initialize_by(attributes, &block) find_by(attributes) || new(attributes, &block) end
#initialize_copy(other)
[ GitHub ]# File 'activerecord/lib/active_record/relation.rb', line 41
def initialize_copy(other) @values = @values.dup reset end
#inspect
[ GitHub ]#joined_includes_values
Joins that are also marked for preloading. In which case we should just eager load them. Note that this is a naive implementation because we could have strings and symbols which represent the same association, but that aren’t matched by this. Also, we could have nested hashes which partially match, e.g. { a: :b } & { a: [:b, :c] }
# File 'activerecord/lib/active_record/relation.rb', line 818
def joined_includes_values includes_values & joins_values end
#load(&block)
Causes the records to be loaded from the database if they have not been loaded already. You can use this if for some reason you need to explicitly load some records before actually using them. The return value is the relation itself, not the records.
Post.where(published: true).load # => #<ActiveRecord::Relation>
# File 'activerecord/lib/active_record/relation.rb', line 750
def load(&block) if !loaded? || scheduled? @records = exec_queries(&block) @loaded = true end self end
#load_async
Schedule the query to be performed from a background thread pool.
Post.where(published: true).load_async # => #<ActiveRecord::Relation>
When the Relation
is iterated, if the background query wasn’t executed yet, it will be performed by the foreground thread.
Note that config.active_record.async_query_executor must be configured for queries to actually be executed concurrently. Otherwise it defaults to executing them in the foreground.
load_async
will also fall back to executing in the foreground in the test environment when transactional fixtures are enabled.
If the query was actually executed in the background, the Active Record logs will show it by prefixing the log line with ASYNC
:
ASYNC Post Load (0.0ms) (db time 2ms) SELECT "posts".* FROM "posts" LIMIT 100
# File 'activerecord/lib/active_record/relation.rb', line 721
def load_async return load if !connection.async_enabled? unless loaded? result = exec_main_query(async: connection.current_transaction.closed?) if result.is_a?(Array) @records = result else @future_result = result end @loaded = true end self end
#loaded (readonly) Also known as: #loaded?
[ GitHub ]# File 'activerecord/lib/active_record/relation.rb', line 22
attr_reader :table, :klass, :loaded, :predicate_builder
#locked?
[ GitHub ]# File 'activerecord/lib/active_record/relation.rb', line 26
alias :locked? :lock_value
#new(attributes = nil, &block) Also known as: #build
Initializes new record from relation while maintaining the current scope.
Expects arguments in the same format as {ActiveRecord::Base
.new}.
users = User.where(name: 'DHH')
user = users.new # => #<User id: nil, name: "DHH", created_at: nil, updated_at: nil>
You can also pass a block to new with the new record as argument:
user = users.new { |user| user.name = 'Oscar' }
user.name # => Oscar
#none?(*args) ⇒ Boolean
Returns true if there are no records.
When a pattern argument is given, this method checks whether elements in the ::Enumerable
match the pattern via the case-equality operator (===
).
posts.none?(Comment) # => true or false
# File 'activerecord/lib/active_record/relation.rb', line 299
def none?(*args) return true if @none return super if args.present? || block_given? empty? end
#one?(*args) ⇒ Boolean
Returns true if there is exactly one record.
When a pattern argument is given, this method checks whether elements in the ::Enumerable
match the pattern via the case-equality operator (===
).
posts.one?(Post) # => true or false
#pretty_print(pp)
[ GitHub ]#reload
Forces reloading of relation.
#reset
[ GitHub ]# File 'activerecord/lib/active_record/relation.rb', line 765
def reset @future_result&.cancel @future_result = nil @delegate_to_klass = false @to_sql = @arel = @loaded = @should_eager_load = nil @offsets = @take = nil @cache_keys = nil @cache_versions = nil @records = nil self end
#scope_for_create
[ GitHub ]#scoping(all_queries: nil, &block)
Scope all queries to the current scope.
Comment.where(post_id: 1).scoping do
Comment.first
end
# SELECT "comments".* FROM "comments" WHERE "comments"."post_id" = 1 ORDER BY "comments"."id" ASC LIMIT 1
If all_queries: true
is passed, scoping will apply to all queries for the relation including #update and delete
on instances. Once all_queries
is set to true it cannot be set to false in a nested block.
Please check unscoped if you want to remove all previous scopes (including the default_scope) during the execution of a block.
# File 'activerecord/lib/active_record/relation.rb', line 460
def scoping(all_queries: nil, &block) registry = klass.scope_registry if global_scope?(registry) && all_queries == false raise ArgumentError, "Scoping is set to apply to all queries and cannot be unset in a nested block." elsif already_in_scope?(registry) yield else _scoping(self, registry, all_queries, &block) end end
#size
Returns size of the records.
#to_a
Alias for #to_ary.
# File 'activerecord/lib/active_record/relation.rb', line 261
alias to_a to_ary
#to_ary Also known as: #to_a
Converts relation objects to ::Array
.
# File 'activerecord/lib/active_record/relation.rb', line 258
def to_ary records.dup end
#to_sql
Returns sql statement for the relation.
User.where(name: 'Oscar').to_sql
# SELECT "users".* FROM "users" WHERE "users"."name" = 'Oscar'
# File 'activerecord/lib/active_record/relation.rb', line 781
def to_sql @to_sql ||= if eager_loading? apply_join_dependency do |relation, join_dependency| relation = join_dependency.apply_column_aliases(relation) relation.to_sql end else conn = klass.connection conn.unprepared_statement { conn.to_sql(arel) } end end
#touch_all(*names, time: nil)
Touches all records in the current relation, setting the updated_at+/+updated_on
attributes to the current time or the time specified. It does not instantiate the involved models, and it does not trigger Active Record callbacks or validations. This method can be passed attribute names and an optional time argument. If attribute names are passed, they are updated along with updated_at+/+updated_on
attributes. If no time argument is passed, the current time is used as default.
Examples
# Touch all records
Person.all.touch_all
# => "UPDATE \"people\" SET \"updated_at\" = '2018-01-04 22:55:23.132670'"
# Touch multiple records with a custom attribute
Person.all.touch_all(:created_at)
# => "UPDATE \"people\" SET \"updated_at\" = '2018-01-04 22:55:23.132670', \"created_at\" = '2018-01-04 22:55:23.132670'"
# Touch multiple records with a specified time
Person.all.touch_all(time: Time.new(2020, 5, 16, 0, 0, 0))
# => "UPDATE \"people\" SET \"updated_at\" = '2020-05-16 00:00:00'"
# Touch records with scope
Person.where(name: 'David').touch_all
# => "UPDATE \"people\" SET \"updated_at\" = '2018-01-04 22:55:23.132670' WHERE \"people\".\"name\" = 'David'"
# File 'activerecord/lib/active_record/relation.rb', line 609
def touch_all(*names, time: nil) update_all klass.touch_attributes_with_time(*names, time: time) end
#update_all(updates)
Updates all records in the current relation with details given. This method constructs a single SQL UPDATE statement and sends it straight to the database. It does not instantiate the involved models and it does not trigger Active Record callbacks or validations. However, values passed to #update_all
will still go through Active Record’s normal type casting and serialization. Returns the number of rows affected.
Note: As Active Record callbacks are not triggered, this method will not automatically update updated_at+/+updated_on
columns.
Parameters
-
updates
- A string, array, or hash representing the SET part of an SQL statement. Any strings provided will be type cast, unless you use Arel.sql. (Don’t pass user-provided values to Arel.sql.)
Examples
# Update all customers with the given attributes
Customer.update_all wants_email: true
# Update all books with 'Rails' in their title
Book.where('title LIKE ?', '%Rails%').update_all(author: 'David')
# Update all books that match conditions, but limit it to 5 ordered by date
Book.where('title LIKE ?', '%Rails%').order(:created_at).limit(5).update_all(author: 'David')
# Update all invoices and set the number column to its id value.
Invoice.update_all('number = id')
# Update all books with 'Rails' in their title
Book.where('title LIKE ?', '%Rails%').update_all(title: Arel.sql("title + ' - volume 1'"))
# File 'activerecord/lib/active_record/relation.rb', line 507
def update_all(updates) raise ArgumentError, "Empty list of attributes to change" if updates.blank? return 0 if @none if updates.is_a?(Hash) if klass.locking_enabled? && !updates.key?(klass.locking_column) && !updates.key?(klass.locking_column.to_sym) attr = table[klass.locking_column] updates[attr.name] = _increment_attribute(attr) end values = _substitute_values(updates) else values = Arel.sql(klass.sanitize_sql_for_assignment(updates, table.name)) end arel = eager_loading? ? apply_join_dependency.arel : build_arel arel.source.left = table group_values_arel_columns = arel_columns(group_values.uniq) having_clause_ast = having_clause.ast unless having_clause.empty? key = if klass.composite_primary_key? primary_key.map { |pk| table[pk] } else table[primary_key] end stmt = arel.compile_update(values, key, having_clause_ast, group_values_arel_columns) klass.connection.update(stmt, "#{klass} Update All").tap { reset } end
#update_counters(counters)
Updates the counters of the records in the current relation.
Parameters
-
counter
- A Hash containing the names of the fields to update as keys and the amount to update as values. -
:touch
option - Touch the timestamp columns when updating. -
If attributes names are passed, they are updated along with update_at/on attributes.
Examples
# For Posts by a given author increment the comment_count by 1.
Post.where(author_id: .id).update_counters(comment_count: 1)
# File 'activerecord/lib/active_record/relation.rb', line 566
def update_counters(counters) touch = counters.delete(:touch) updates = {} counters.each do |counter_name, value| attr = table[counter_name] updates[attr.name] = _increment_attribute(attr, value) end if touch names = touch if touch != true names = Array.wrap(names) = names. touch_updates = klass.touch_attributes_with_time(*names, ** ) updates.merge!(touch_updates) unless touch_updates.empty? end update_all updates end
#values
[ GitHub ]# File 'activerecord/lib/active_record/relation.rb', line 848
def values @values.dup end