Class: DB::Model::Statement::Select

Inherits:
Object
  • Object
show all
Defined in:
lib/db/model/statement/select.rb

Instance Method Summary collapse

Constructor Details

#initialize(source, fields: nil, where: nil, limit: nil) ⇒ Select

Returns a new instance of Select.



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# File 'lib/db/model/statement/select.rb', line 27

def initialize(source, fields: nil, where: nil, limit: nil)
	@source = source
	@fields = fields
	@where = where
	@limit = limit
end

Instance Method Details

#append_to(statement, limit: @limit) ⇒ Object 



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# File 'lib/db/model/statement/select.rb', line 34

def append_to(statement, limit: @limit)
	statement = statement.clause("SELECT")
	
	if @fields
		@fields.append_to(statement)
	else
		statement.clause("*")
	end
	
	statement.clause("FROM")
	statement.identifier(@source.type)
	
	if @where
		statement.clause "WHERE"
		@where.append_to(statement)
	end
	
	limit&.append_to(statement)
	
	return statement
end

#apply(context, result, cache = nil) ⇒ Object 



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# File 'lib/db/model/statement/select.rb', line 68

def apply(context, result, cache = nil)
	keys = result.field_names.map(&:to_sym)
	
	result.map do |row|
		@source.new(context, keys.zip(row).to_h, cache)
	end
end

#each(context, cache = nil) ⇒ Object 



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# File 'lib/db/model/statement/select.rb', line 76

def each(context, cache = nil)
	to_sql(context).call do |connection|
		result = connection.next_result
		keys = result.field_names.map(&:to_sym)
		
		result.each do |row|
			yield @source.new(context, keys.zip(row).to_h, cache)
		end
	end
end

#first(context, count, cache = nil) ⇒ Object 



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# File 'lib/db/model/statement/select.rb', line 87

def first(context, count, cache = nil)
	limit = @limit&.first(count) || Limit.new(count)
	
	append_to(context, limit: limit).call do |connection|
		result = connection.next_result
		
		return apply(context, result, cache)
	end
end

#to_a(context, cache = nil) ⇒ Object 



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# File 'lib/db/model/statement/select.rb', line 60

def to_a(context, cache = nil)
	to_sql(context).call do |connection|
		result = connection.next_result
		
		return apply(context, result, cache)
	end
end

#to_sql(context) ⇒ Object 



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# File 'lib/db/model/statement/select.rb', line 56

def to_sql(context)
	self.append_to(context)
end