class AWS::DynamoDB::Item

Represents a DynamoDB item. An item is identified by simple or complex primary key (according to the table schema) and consists of a collection of attributes. Attributes are name/value pairs where the value may be a string, number, string set, or number set.

Getting an item by hash key value:

item = table.items['hash-key-value']

Getting an item from a table with both hash and range keys:

item = table.items['hash-key','range-key']

Attributes

hash_value[R]

@return [String, Numeric] The hash key value of the item.

range_value[R]

@return [String, Numeric, nil] The range key value of the

item, or +nil+ if the table has a simple primary key.

table[R]

@return [Table] The table in which the item is stored.

Public Class Methods

new(table, *args) click to toggle source

@private

# File lib/aws/dynamo_db/item.rb, line 48
def initialize(table, *args)
  opts = args.pop if args.last.kind_of?(Hash)
  (@hash_value, @range_value) = args
  @table = table
  super(table, opts)
end

new_from(op, response_object, table, *args) click to toggle source

@private

# File lib/aws/dynamo_db/item.rb, line 104
def self.new_from(op, response_object, table, *args)
  table.assert_schema!
  hash_value =
    value_from_response(response_object[table.hash_key.name])
  range_value =
    value_from_response(response_object[table.range_key.name]) if
    table.range_key

  raise "missing hash key value in put_item response" unless hash_value
  raise "missing range key value in put_item response" unless
    range_value || !table.range_key

  super(op, response_object,
        table, hash_value, range_value, *args)
end

Public Instance Methods

attributes() click to toggle source

@return [AttributeCollection] An object representing the

attributes of the item.

# File lib/aws/dynamo_db/item.rb, line 99
def attributes
  AttributeCollection.new(self)
end

delete(options = {}) click to toggle source

Deletes the item.

@param [Hash] options Options for deleting the item.

@option options [Hash] :if Designates a conditional delete.

The operation will fail unless the item exists and has the
attributes in the value for this option.  For example:

  # throws DynamoDB::Errors::ConditionalCheckFailedException
  # unless the item has "color" set to "red"
  item.delete(:if => { :color => "red" })

@option options [String, Symbol, Array] :unless_exists A name

or collection of attribute names; if the item has a value
for any of these attributes, this method will raise
+DynamoDB::Errors::ConditionalCheckFailedException+.  For
example:

  item.delete(:unless_exists => "version")

# File lib/aws/dynamo_db/item.rb, line 74
def delete(options = {})
  client_opts = item_key_options(self)

  expected = expect_conditions(options)
  client_opts[:expected] = expected unless expected.empty?

  client_opts[:return_values] = options[:return].to_s.upcase if
    options[:return]

  resp = client.delete_item(client_opts)

  values_from_response_hash(resp.data["Attributes"]) if
    options[:return] and resp.data["Attributes"]
end

exists?(options = {}) click to toggle source

@return [Boolean] True if the item exists.

# File lib/aws/dynamo_db/item.rb, line 90
def exists?(options = {})
  client_opts = item_key_options(self, options)
  client_opts[:attributes_to_get] = [table.hash_key.name]
  resp = client.get_item(client_opts)
  resp.data.key?("Item")
end

Protected Instance Methods

resource_identifiers() click to toggle source

# File lib/aws/dynamo_db/item.rb, line 121
def resource_identifiers
  [[:table_name, table.name],
   [:hash_value, hash_value],
   [:range_value, range_value]]
end