Module: ObjectidColumns

Defined in:
lib/objectid_columns.rb,
lib/objectid_columns/version.rb,
lib/objectid_columns/active_record/base.rb,
lib/objectid_columns/arel/visitors/to_sql.rb,
lib/objectid_columns/has_objectid_columns.rb,
lib/objectid_columns/active_record/relation.rb,
lib/objectid_columns/dynamic_methods_module.rb,
lib/objectid_columns/objectid_columns_manager.rb

Overview

What’s the current version of this gem?

Defined Under Namespace

Modules: ActiveRecord, Arel, HasObjectidColumns Classes: DynamicMethodsModule, ObjectidColumnsManager

Constant Summary collapse

SUPPORTED_OBJECTID_BSON_CLASS_NAMES =

This is the set of classes we support for representing ObjectIds, as objects, themselves. BSON::ObjectId comes from the bson gem, and Moped::BSON::ObjectId comes from the moped gem.

Note that this gem does not declare a dependency on either one of these gems, because we want you to be able to use either, and there’s currently no way of expressing that explicitly. Instead, .available_objectid_columns_bson_classes, below, takes care of figuring out which ones are availble and loading them.

Order is important here: when creating new ObjectId objects (such as when reading from an ObjectId column), we will prefer the earliest one of these classes that is actually defined. You can change this using .preferred_bson_class=, below.

Any class added here has to obey the following constraints:

  • You can create a new instance from a hex string using .from_string(hex_string)

  • Calling #to_s on it returns a hexadecimal String of exactly 24 characters

Both these objects currently do. If they change, or you want to introduce a new ObjectId representation class, a small amount of refactoring will be necessary.

%w{BSON::ObjectId Moped::BSON::ObjectId}
VERSION = 
"1.0.5"

Class Method Summary collapse

Class Method Details

.available_objectid_columns_bson_classes ⇒ Object

Returns an array of Class objects – of length at least 1, but potentially more than 1 – of the various ObjectId classes we have available to use. Again, because we don’t explicitly depend on the BSON gems (see above), this needs to take care of trying to load and require the gems in question, and fail gracefully if they’re not present.



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# File 'lib/objectid_columns.rb', line 54

def available_objectid_columns_bson_classes
  @available_objectid_columns_bson_classes ||= begin
    # Try to load both gems, but don't fail if there are errors
    %w{moped bson}.each do |require_name|
      begin
        gem require_name
      rescue Gem::LoadError => le
      end

      begin
        require require_name
      rescue LoadError => le
      end
    end

    # See which classes we have managed to load
    defined_classes = SUPPORTED_OBJECTID_BSON_CLASS_NAMES.map do |name|
      eval("if defined?(#{name}) then #{name} end")
    end.compact

    # Raise an error if we haven't loaded either
    if defined_classes.length == 0
      raise %{ObjectidColumns requires a library that implements an ObjectId class to be loaded; we support
the following ObjectId classes: #{SUPPORTED_OBJECTID_BSON_CLASS_NAMES.join(", ")}.
(These are from the 'bson' or 'moped' gems.) You seem to have neither one installed.

Please add one of these gems to your project and try again. Usually, this just means
adding this to your Gemfile:

gem 'bson'

(ObjectidColumns does not explicitly depend on either of these, because we want you
to be able to choose whichever one you prefer.)}
    end

    defined_classes
  end
end

.construct_objectid(hex_string) ⇒ Object

Creates a new BSON ObjectId from the given String, which must be in the hexadecimal format.



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# File 'lib/objectid_columns.rb', line 99

def construct_objectid(hex_string)
  preferred_bson_class.send(:from_string, hex_string)
end

.is_valid_bson_object?(x) ⇒ Boolean

Is the given object a valid BSON ObjectId? This doesn’t count Strings in any format – only objects.

Returns:

  • (Boolean) 


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# File 'lib/objectid_columns.rb', line 94

def is_valid_bson_object?(x)
  available_objectid_columns_bson_classes.detect { |k| x.kind_of?(k) }
end

.new_objectid ⇒ Object

Creates a new BSON ObjectId, from scratch; this must return an ObjectId with a value, suitable for assigning to a newly-created row. We use this only if you’ve declared that your primary key column is an ObjectId, and then only if you’re about to save a new row and it has no ID yet.



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# File 'lib/objectid_columns.rb', line 106

def new_objectid
  preferred_bson_class.new
end

.preferred_bson_class ⇒ Object

When we create a new ObjectId object (such as when reading from a column), what class should it be? If you have multiple classes loaded and you don’t like this one, you can call .preferred_bson_class=, below.



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# File 'lib/objectid_columns.rb', line 37

def preferred_bson_class
  @preferred_bson_class ||= available_objectid_columns_bson_classes.first
end

.preferred_bson_class=(bson_class) ⇒ Object

Sets the preferred BSON class to the given class.



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# File 'lib/objectid_columns.rb', line 42

def preferred_bson_class=(bson_class)
  unless SUPPORTED_OBJECTID_BSON_CLASS_NAMES.include?(bson_class.name)
    raise ArgumentError, "ObjectidColumns does not support BSON class #{bson_class.name}; it supports: #{SUPPORTED_OBJECTID_BSON_CLASS_NAMES.inspect}"
  end

  @preferred_bson_class = bson_class
end