Class: Aws::Record::TableConfig

Inherits:
Object
  • Object
show all
Defined in:
lib/aws-record/record/table_config.rb

Overview

Aws::Record::TableConfig provides a DSL for describing and modifying the remote configuration of your DynamoDB tables. A table configuration object can perform intelligent comparisons and incremental migrations versus the current remote configuration, if the table exists, or do a full create if it does not. In this manner, table configuration becomes fully declarative.

Examples:

A basic model with configuration.

class Model
  include Aws::Record
  string_attr :uuid, hash_key: true
end

table_config = Aws::Record::TableConfig.define do |t|
  t.model_class Model
  t.read_capacity_units 10
  t.write_capacity_units 5
end

Running a conditional migration on a basic model.

table_config = Aws::Record::TableConfig.define do |t|
  t.model_class Model
  t.read_capacity_units 10
  t.write_capacity_units 5
end

table_config.migrate! unless table_config.compatible?

A model with a global secondary index.

class Forum
  include Aws::Record
  string_attr     :forum_uuid, hash_key: true
  integer_attr    :post_id,    range_key: true
  string_attr     :post_title
  string_attr     :post_body
  string_attr     :author_username
  datetime_attr   :created_date
  datetime_attr   :updated_date
  string_set_attr :tags
  map_attr        :metadata, default_value: {}

  global_secondary_index(
    :title,
    hash_key:  :forum_uuid,
    range_key: :post_title,
    projection_type: "ALL"
  )
end

table_config = Aws::Record::TableConfig.define do |t|
  t.model_class Forum
  t.read_capacity_units 10
  t.write_capacity_units 5

  t.global_secondary_index(:title) do |i|
    i.read_capacity_units 5
    i.write_capacity_units 5
  end
end

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Instance Attribute Details

#clientObject

Returns the value of attribute client



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# File 'lib/aws-record/record/table_config.rb', line 79

def client
  @client
end

Class Method Details

.define(&block) ⇒ Object

Creates a new table configuration, using a DSL in the provided block. The DSL has the following methods:

  • #model_class A class name reference to the Aws::Record model class.

  • #read_capacity_units Sets the read capacity units for the table.

  • #write_capacity_units Sets the write capacity units for the table.

  • #global_secondary_index(index_symbol, &block) Defines a global secondary index with capacity attributes in a block:

    • #read_capacity_units Sets the read capacity units for the index.

    • #write_capacity_units Sets the write capacity units for the index.

Examples:

Defining a migration with a GSI.

class Forum
  include Aws::Record
  string_attr     :forum_uuid, hash_key: true
  integer_attr    :post_id,    range_key: true
  string_attr     :post_title
  string_attr     :post_body
  string_attr     :author_username
  datetime_attr   :created_date
  datetime_attr   :updated_date
  string_set_attr :tags
  map_attr        :metadata, default_value: {}

  global_secondary_index(
    :title,
    hash_key:  :forum_uuid,
    range_key: :post_title,
    projection_type: "ALL"
  )
end

table_config = Aws::Record::TableConfig.define do |t|
  t.model_class Forum
  t.read_capacity_units 10
  t.write_capacity_units 5

  t.global_secondary_index(:title) do |i|
    i.read_capacity_units 5
    i.write_capacity_units 5
  end
end


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# File 'lib/aws-record/record/table_config.rb', line 127

def define(&block)
  cfg = TableConfig.new
  cfg.instance_eval(&block)
  cfg.configure_client
  cfg
end

Instance Method Details

#compatible?Boolean

Checks the remote table for compatibility. Similar to #exact_match?, this will return false if the remote table does not exist. It also checks the keys, declared global secondary indexes, declared attribute definitions, and throughput for exact matches. However, if the remote end has additional attribute definitions and global secondary indexes not defined in your config, will still return true. This allows for a check that is friendly to single table inheritance use cases.

Returns:

  • (Boolean)

    true if remote is compatible, false otherwise.



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# File 'lib/aws-record/record/table_config.rb', line 224

def compatible?
  begin
    resp = @client.describe_table(table_name: @model_class.table_name)
    _compatible_check(resp)
  rescue DynamoDB::Errors::ResourceNotFoundException
    false
  end
end

#exact_match?Boolean

Checks against the remote table's configuration. If the remote table does not exist, guaranteed false. Otherwise, will check if the remote throughput, keys, attribute definitions, and global secondary indexes are exactly equal to your declared configuration.

Returns:

  • (Boolean)

    true if remote is an exact match, false otherwise.



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# File 'lib/aws-record/record/table_config.rb', line 239

def exact_match?
  begin
    resp = @client.describe_table(table_name: @model_class.table_name)
    _throughput_equal(resp) &&
      _keys_equal(resp) &&
      _ad_equal(resp) &&
      _gsi_equal(resp)
  rescue DynamoDB::Errors::ResourceNotFoundException
    false
  end
end

#migrate!Object

Performs a migration, if needed, against the remote table. If #compatible? would return true, the remote table already has the same throughput, key schema, attribute definitions, and global secondary indexes, so no further API calls are made. Otherwise, a DynamoDB table will be created or updated to match your declared configuration.



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# File 'lib/aws-record/record/table_config.rb', line 178

def migrate!
  _validate_required_configuration
  begin
    resp = @client.describe_table(table_name: @model_class.table_name)
    if _compatible_check(resp)
      nil
    else
      # Gotcha: You need separate migrations for indexes and throughput
      unless _throughput_equal(resp)
        @client.update_table(
          table_name: @model_class.table_name,
          provisioned_throughput: {
            read_capacity_units: @read_capacity_units,
            write_capacity_units: @write_capacity_units
          }
        )
        @client.wait_until(
          :table_exists,
          table_name: @model_class.table_name
        )
      end
      unless _gsi_superset(resp)
        @client.update_table(_update_index_opts(resp))
        @client.wait_until(
        :table_exists,
        table_name: @model_class.table_name
      )
      end
    end
  rescue DynamoDB::Errors::ResourceNotFoundException
    # Code Smell: Exception as control flow.
    # Can I use SDK ability to skip raising an exception for this?
    @client.create_table(_create_table_opts)
    @client.wait_until(:table_exists, table_name: @model_class.table_name)
  end
end