Skip to content
This repository
tree: b8640d4790
Fetching contributors…

Cannot retrieve contributors at this time

file 354 lines (313 sloc) 12.371 kb
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354
module ActiveRecord
  module FinderMethods
    # Find by id - This can either be a specific id (1), a list of ids (1, 5, 6), or an array of ids ([5, 6, 10]).
    # If no record can be found for all of the listed ids, then RecordNotFound will be raised. If the primary key
    # is an integer, find by id coerces its arguments using +to_i+.
    #
    # Person.find(1) # returns the object for ID = 1
    # Person.find("1") # returns the object for ID = 1
    # Person.find(1, 2, 6) # returns an array for objects with IDs in (1, 2, 6)
    # Person.find([7, 17]) # returns an array for objects with IDs in (7, 17)
    # Person.find([1]) # returns an array for the object with ID = 1
    # Person.where("administrator = 1").order("created_on DESC").find(1)
    #
    # Note that returned records may not be in the same order as the ids you
    # provide since database rows are unordered. Give an explicit <tt>order</tt>
    # to ensure the results are sorted.
    #
    # ==== Find with lock
    #
    # Example for find with a lock: Imagine two concurrent transactions:
    # each will read <tt>person.visits == 2</tt>, add 1 to it, and save, resulting
    # in two saves of <tt>person.visits = 3</tt>. By locking the row, the second
    # transaction has to wait until the first is finished; we get the
    # expected <tt>person.visits == 4</tt>.
    #
    # Person.transaction do
    # person = Person.lock(true).find(1)
    # person.visits += 1
    # person.save!
    # end
    def find(*args)
      if block_given?
        to_a.find { |*block_args| yield(*block_args) }
      else
        find_with_ids(*args)
      end
    end

    # Finds the first record matching the specified conditions. There
    # is no implied ordering so if order matters, you should specify it
    # yourself.
    #
    # If no record is found, returns <tt>nil</tt>.
    #
    # Post.find_by name: 'Spartacus', rating: 4
    # Post.find_by "published_at < ?", 2.weeks.ago
    def find_by(*args)
      where(*args).take
    end

    # Like <tt>find_by</tt>, except that if no record is found, raises
    # an <tt>ActiveRecord::RecordNotFound</tt> error.
    def find_by!(*args)
      where(*args).take!
    end

    # Gives a record (or N records if a parameter is supplied) without any implied
    # order. The order will depend on the database implementation.
    # If an order is supplied it will be respected.
    #
    # Person.take # returns an object fetched by SELECT * FROM people LIMIT 1
    # Person.take(5) # returns 5 objects fetched by SELECT * FROM people LIMIT 5
    # Person.where(["name LIKE '%?'", name]).take
    def take(limit = nil)
      limit ? limit(limit).to_a : find_take
    end

    # Same as +take+ but raises <tt>ActiveRecord::RecordNotFound</tt> if no record
    # is found. Note that <tt>take!</tt> accepts no arguments.
    def take!
      take or raise RecordNotFound
    end

    # Find the first record (or first N records if a parameter is supplied).
    # If no order is defined it will order by primary key.
    #
    # Person.first # returns the first object fetched by SELECT * FROM people
    # Person.where(["user_name = ?", user_name]).first
    # Person.where(["user_name = :u", { u: user_name }]).first
    # Person.order("created_on DESC").offset(5).first
    # Person.first(3) # returns the first three objects fetched by SELECT * FROM people LIMIT 3
    #
    # ==== Rails 3
    #
    # Person.first # SELECT "users".* FROM "users" LIMIT 1
    #
    # NOTE: Rails 3 may not +order+ this query by be the primary key.
    # The order will depend on the database implementation.
    # In order to ensure that behavior use <tt>User.order(:id).first</tt> instead.
    #
    # ==== Rails 4
    #
    # Person.first # SELECT "users".* FROM "users" ORDER BY "users"."id" ASC LIMIT 1
    #
    def first(limit = nil)
      if limit
        if order_values.empty? && primary_key
          order(arel_table[primary_key].asc).limit(limit).to_a
        else
          limit(limit).to_a
        end
      else
        find_first
      end
    end

    # Same as +first+ but raises <tt>ActiveRecord::RecordNotFound</tt> if no record
    # is found. Note that <tt>first!</tt> accepts no arguments.
    def first!
      first or raise RecordNotFound
    end

    # Find the last record (or last N records if a parameter is supplied).
    # If no order is defined it will order by primary key.
    #
    # Person.last # returns the last object fetched by SELECT * FROM people
    # Person.where(["user_name = ?", user_name]).last
    # Person.order("created_on DESC").offset(5).last
    # Person.last(3) # returns the last three objects fetched by SELECT * FROM people.
    #
    # Take note that in that last case, the results are sorted in ascending order:
    #
    # [#<Person id:2>, #<Person id:3>, #<Person id:4>]
    #
    # and not:
    #
    # [#<Person id:4>, #<Person id:3>, #<Person id:2>]
    def last(limit = nil)
      if limit
        if order_values.empty? && primary_key
          order(arel_table[primary_key].desc).limit(limit).reverse
        else
          to_a.last(limit)
        end
      else
        find_last
      end
    end

    # Same as +last+ but raises <tt>ActiveRecord::RecordNotFound</tt> if no record
    # is found. Note that <tt>last!</tt> accepts no arguments.
    def last!
      last or raise RecordNotFound
    end

    # Returns truthy if a record exists in the table that matches the +id+ or
    # conditions given, or falsy otherwise. The argument can take six forms:
    #
    # * Integer - Finds the record with this primary key.
    # * String - Finds the record with a primary key corresponding to this
    # string (such as <tt>'5'</tt>).
    # * Array - Finds the record that matches these +find+-style conditions
    # (such as <tt>['color = ?', 'red']</tt>).
    # * Hash - Finds the record that matches these +find+-style conditions
    # (such as <tt>{color: 'red'}</tt>).
    # * +false+ - Returns always +false+.
    # * No args - Returns +false+ if the table is empty, +true+ otherwise.
    #
    # For more information about specifying conditions as a Hash or Array,
    # see the Conditions section in the introduction to ActiveRecord::Base.
    #
    # Note: You can't pass in a condition as a string (like <tt>name =
    # 'Jamie'</tt>), since it would be sanitized and then queried against
    # the primary key column, like <tt>id = 'name = \'Jamie\''</tt>.
    #
    # Person.exists?(5)
    # Person.exists?('5')
    # Person.exists?(['name LIKE ?', "%#{query}%"])
    # Person.exists?(name: 'David')
    # Person.exists?(false)
    # Person.exists?
    def exists?(conditions = :none)
      conditions = conditions.id if Base === conditions
      return false if !conditions

      join_dependency = construct_join_dependency
      relation = construct_relation_for_association_find(join_dependency)
      relation = relation.except(:select, :order).select("1 AS one").limit(1)

      case conditions
      when Array, Hash
        relation = relation.where(conditions)
      else
        relation = relation.where(table[primary_key].eq(conditions)) if conditions != :none
      end

      connection.select_value(relation, "#{name} Exists", relation.bind_values)
    rescue ThrowResult
      false
    end

    # This method is called whenever no records are found with either a single
    # id or multiple ids and raises a +ActiveRecord::RecordNotFound+ exception.
    #
    # The error message is different depending on whether a single id or
    # multiple ids are provided. If multiple ids are provided, then the number
    # of results obtained should be provided in the +result_size+ argument and
    # the expected number of results should be provided in the +expected_size+
    # argument.
    def raise_record_not_found_exception!(ids, result_size, expected_size) #:nodoc:
      conditions = arel.where_sql
      conditions = " [#{conditions}]" if conditions

      if Array(ids).size == 1
        error = "Couldn't find #{@klass.name} with #{primary_key}=#{ids}#{conditions}"
      else
        error = "Couldn't find all #{@klass.name.pluralize} with IDs "
        error << "(#{ids.join(", ")})#{conditions} (found #{result_size} results, but was looking for #{expected_size})"
      end

      raise RecordNotFound, error
    end

    protected

    def find_with_associations
      join_dependency = construct_join_dependency
      relation = construct_relation_for_association_find(join_dependency)
      rows = connection.select_all(relation, 'SQL', relation.bind_values.dup)
      join_dependency.instantiate(rows)
    rescue ThrowResult
      []
    end

    def construct_join_dependency(joins = [])
      including = (eager_load_values + includes_values).uniq
      ActiveRecord::Associations::JoinDependency.new(@klass, including, joins)
    end

    def construct_relation_for_association_calculations
      apply_join_dependency(self, construct_join_dependency(arel.froms.first))
    end

    def construct_relation_for_association_find(join_dependency)
      relation = except(:select).select(join_dependency.columns)
      apply_join_dependency(relation, join_dependency)
    end

    def apply_join_dependency(relation, join_dependency)
      relation = relation.except(:includes, :eager_load, :preload)
      relation = join_dependency.join_relation(relation)

      if using_limitable_reflections?(join_dependency.reflections)
        relation
      else
        relation.where!(construct_limited_ids_condition(relation)) if relation.limit_value
        relation.except(:limit, :offset)
      end
    end

    def construct_limited_ids_condition(relation)
      values = @klass.connection.columns_for_distinct(
        "#{quoted_table_name}.#{quoted_primary_key}", relation.order_values)

      relation = relation.except(:select).select(values).distinct!

      id_rows = @klass.connection.select_all(relation.arel, 'SQL', relation.bind_values)
      ids_array = id_rows.map {|row| row[primary_key]}

      ids_array.empty? ? raise(ThrowResult) : table[primary_key].in(ids_array)
    end

    def find_with_ids(*ids)
      expects_array = ids.first.kind_of?(Array)
      return ids.first if expects_array && ids.first.empty?

      ids = ids.flatten.compact.uniq

      case ids.size
      when 0
        raise RecordNotFound, "Couldn't find #{@klass.name} without an ID"
      when 1
        result = find_one(ids.first)
        expects_array ? [ result ] : result
      else
        find_some(ids)
      end
    end

    def find_one(id)
      id = id.id if ActiveRecord::Base === id

      column = columns_hash[primary_key]
      substitute = connection.substitute_at(column, bind_values.length)
      relation = where(table[primary_key].eq(substitute))
      relation.bind_values += [[column, id]]
      record = relation.take

      raise_record_not_found_exception!(id, 0, 1) unless record

      record
    end

    def find_some(ids)
      result = where(table[primary_key].in(ids)).to_a

      expected_size =
        if limit_value && ids.size > limit_value
          limit_value
        else
          ids.size
        end

      # 11 ids with limit 3, offset 9 should give 2 results.
      if offset_value && (ids.size - offset_value < expected_size)
        expected_size = ids.size - offset_value
      end

      if result.size == expected_size
        result
      else
        raise_record_not_found_exception!(ids, result.size, expected_size)
      end
    end

    def find_take
      if loaded?
        @records.first
      else
        @take ||= limit(1).to_a.first
      end
    end

    def find_first
      if loaded?
        @records.first
      else
        @first ||=
          if with_default_scope.order_values.empty? && primary_key
            order(arel_table[primary_key].asc).limit(1).to_a.first
          else
            limit(1).to_a.first
          end
      end
    end

    def find_last
      if loaded?
        @records.last
      else
        @last ||=
          if offset_value || limit_value
            to_a.last
          else
            reverse_order.limit(1).to_a.first
          end
      end
    end

    def using_limitable_reflections?(reflections)
      reflections.none? { |r| r.collection? }
    end
  end
end
Something went wrong with that request. Please try again.