Class: DB::Query

Inherits:
Object
  • Object
show all
Defined in:
lib/db/query.rb

Overview

A mutable query builder.

Instance Method Summary collapse

Constructor Details

#initialize(session, buffer = String.new) ⇒ Query

Create a new query builder attached to the specified session.



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# File 'lib/db/query.rb', line 48

def initialize(session, buffer = String.new)
  @session = session
  @connection = session.connection
  @buffer = +buffer
end

Instance Method Details

#call ⇒ Object

Send the query to the remote server to be executed. See Context::Session#call for more details.



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# File 'lib/db/query.rb', line 123

def call
  @session.call(@buffer)
end

#clause(value) ⇒ Object

Append a raw textual clause to the query buffer.



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# File 'lib/db/query.rb', line 57

def clause(value)
  @buffer << ' ' unless @buffer.end_with?(' ') || @buffer.empty?
  
  @buffer << value
  
  return self
end

#identifier(value) ⇒ Object

Append an identifier value to the query buffer. Escapes the field according to the requirements of the underlying connection.



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# File 'lib/db/query.rb', line 81

def identifier(value)
  @buffer << ' ' unless @buffer.end_with?(' ')
  
  @connection.append_identifier(value, @buffer)
  
  return self
end

#inspect ⇒ Object 



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# File 'lib/db/query.rb', line 131

def inspect
  "\#<#{self.class} #{@buffer.inspect}>"
end

#interpolate(fragment, **parameters) ⇒ Object

Interpolate a query fragment with the specified parameters. The parameters are escaped before being appended.



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# File 'lib/db/query.rb', line 95

def interpolate(fragment, **parameters)
  parameters.transform_values! do |value|
    case value
    when Symbol, Identifier
      @connection.append_identifier(value)
    else
      @connection.append_literal(value)
    end
  end
  
  @buffer << sprintf(fragment, parameters)
  
  return self
end

#key_column(*arguments, **options) ⇒ Object 



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# File 'lib/db/query.rb', line 110

def key_column(*arguments, **options)
  @buffer << @connection.key_column(*arguments, **options)
  
  return self
end

#literal(value) ⇒ Object

Append a literal value to the query buffer. Escapes the field according to the requirements of the underlying connection.



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# File 'lib/db/query.rb', line 69

def literal(value)
  @buffer << ' ' unless @buffer.end_with?(' ')
  
  @connection.append_literal(value, @buffer)
  
  return self
end

#send ⇒ Object

Send the query to the remote server to be executed. See Context::Session#send_query for more details.



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# File 'lib/db/query.rb', line 117

def send
  @session.send_query(@buffer)
end

#to_s ⇒ Object 



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# File 'lib/db/query.rb', line 127

def to_s
  @buffer
end