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6f08db05c0
There's a lot more that can be moved to these, but this felt like a good place to introduce the object. Plans are: - Remove all knowledge of type casting from the columns, beyond a reference to the cast_type - Move type_cast_for_database to these objects - Potentially make them mutable, introduce a state machine, and have dirty checking handled here as well - Move `attribute`, `decorate_attribute`, and anything else that modifies types to mess with this object, not the columns hash - Introduce a collection object to manage these, reduce allocations, and not require serializing the types
120 lines
2.8 KiB
Ruby
120 lines
2.8 KiB
Ruby
module ActiveRecord
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###
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# This class encapsulates a Result returned from calling +exec_query+ on any
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# database connection adapter. For example:
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#
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# result = ActiveRecord::Base.connection.exec_query('SELECT id, title, body FROM posts')
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# result # => #<ActiveRecord::Result:0xdeadbeef>
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#
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# # Get the column names of the result:
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# result.columns
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# # => ["id", "title", "body"]
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#
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# # Get the record values of the result:
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# result.rows
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# # => [[1, "title_1", "body_1"],
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# [2, "title_2", "body_2"],
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# ...
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# ]
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#
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# # Get an array of hashes representing the result (column => value):
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# result.to_hash
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# # => [{"id" => 1, "title" => "title_1", "body" => "body_1"},
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# {"id" => 2, "title" => "title_2", "body" => "body_2"},
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# ...
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# ]
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#
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# # ActiveRecord::Result also includes Enumerable.
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# result.each do |row|
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# puts row['title'] + " " + row['body']
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# end
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class Result
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include Enumerable
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IDENTITY_TYPE = Type::Value.new # :nodoc:
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attr_reader :columns, :rows, :column_types
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def initialize(columns, rows, column_types = {})
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@columns = columns
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@rows = rows
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@hash_rows = nil
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@column_types = column_types
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end
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def identity_type # :nodoc:
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IDENTITY_TYPE
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end
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def column_type(name)
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@column_types[name] || identity_type
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end
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def each
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if block_given?
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hash_rows.each { |row| yield row }
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else
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hash_rows.to_enum { @rows.size }
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end
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end
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def to_hash
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hash_rows
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end
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alias :map! :map
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alias :collect! :map
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# Returns true if there are no records.
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def empty?
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rows.empty?
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end
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def to_ary
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hash_rows
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end
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def [](idx)
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hash_rows[idx]
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end
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def last
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hash_rows.last
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end
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def initialize_copy(other)
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@columns = columns.dup
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@rows = rows.dup
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@column_types = column_types.dup
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@hash_rows = nil
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end
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private
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def hash_rows
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@hash_rows ||=
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begin
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# We freeze the strings to prevent them getting duped when
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# used as keys in ActiveRecord::Base's @attributes hash
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columns = @columns.map { |c| c.dup.freeze }
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@rows.map { |row|
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# In the past we used Hash[columns.zip(row)]
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# though elegant, the verbose way is much more efficient
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# both time and memory wise cause it avoids a big array allocation
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# this method is called a lot and needs to be micro optimised
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hash = {}
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index = 0
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length = columns.length
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while index < length
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hash[columns[index]] = row[index]
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index += 1
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end
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hash
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}
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end
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end
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end
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end
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