class Sequel::Unbinder

  1. lib/sequel/ast_transformer.rb
Parent: Sequel

Unbinder is used to take a dataset filter and return a modified version that unbinds already bound values and returns a dataset with bound value placeholders and a hash of bind values. You can then prepare the dataset and use the bound variables to execute it with the same values.

This class only does a limited form of unbinding where the variable names and values can be associated unambiguously. The only cases it handles are <tt>SQL::ComplexExpression<tt> with an operator in UNBIND_OPS, a first argument that’s an instance of a member of UNBIND_KEY_CLASSES, and a second argument that’s an instance of a member of UNBIND_VALUE_CLASSES.

So it can handle cases like:

DB.filter(:a=>1).exclude(:b=>2).where{c > 3}

But it cannot handle cases like:

DB.filter(:a + 1 < 0)

Methods

Public Class

  1. new

Public Instance

  1. binds

Constants

UNBIND_KEY_CLASSES = [Symbol, SQL::Identifier, SQL::QualifiedIdentifier]  

The key classes (first argument of the ComplexExpression) that will considered for transformation.
UNBIND_OPS = [:'=', :'!=', :<, :>, :<=, :>=]  

The <tt>SQL::ComplexExpression<tt> operates that will be considered for transformation.
UNBIND_VALUE_CLASSES = [Numeric, String, Date, Time]  

The value classes (second argument of the ComplexExpression) that will be considered for transformation.

Attributes

binds [R]

The hash of bind variables that were extracted from the dataset filter.

Public Class methods

new ()

Intialize an empty binds hash.

[show source] 
# File lib/sequel/ast_transformer.rb, line 152
def initialize
  @binds = {}
end