class Commutator::Expressions::UpdateExpression
See: goo.gl/qiHKO3
Constructs composable UpdateExpression
for use in DynamoDB API calls. Call to_s
when sending to DynamoDB.
Note: SET, REMOVE, ADD, and DELETE pass their arguments to the Statement
constructor. Read the docs there for placeholder syntax.
Usage: exp = Commutator::Expressions::UpdateExpression.new
.set('username = :?', values: ['user1']) .set('email = :?', values: ['a@b.c']) .add('login_count :?', values: [1]) .remove('some_attribute') .delete('some_set :?', values: [10])
The expression above would produce the following with ‘to_s`
“SET username = :VALUE_91120aaf65529fbdc83e66ea160f17bc,
email = :VALUE_73a839aafcf0207ab931d9edd6369a9a ADD login_count :VALUE_c4ca4238a0b923820dcc509a6f75849b REMOVE some_attribute DELETE some_set :VALUE_d3d9446802a44259755d38e6d163e820"
Attributes
attribute_names[R]
attribute_values[R]
Public Class Methods
new(attribute_names: nil, attribute_values: nil, &block)
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# File lib/commutator/expressions/update_expression.rb, line 30 def initialize(attribute_names: nil, attribute_values: nil, &block) @attribute_names = attribute_names || AttributeNames.new @attribute_values = attribute_values || AttributeValues.new end
Public Instance Methods
add_to_section(name, exp, names: [], values: [])
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# File lib/commutator/expressions/update_expression.rb, line 45 def add_to_section(name, exp, names: [], values: []) names.each { |n| attribute_names.add(n) } values.each { |v| attribute_values.add(v) } sections[name] << Statement.new(exp, names: names, values: values) self end
sections()
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# File lib/commutator/expressions/update_expression.rb, line 35 def sections @sections ||= Hash.new { |h, v| h[v] = [] } end
to_s()
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# File lib/commutator/expressions/update_expression.rb, line 54 def to_s sections .map { |name, actions| "#{name.upcase} #{actions.join(', ')}" } .join(' ') end