Validate all keys in a hash match *valid keys, raising ArgumentError on a mismatch. Note that keys are NOT treated indifferently, meaning if you use strings for keys but assert symbols as keys, this will fail.

Examples

{ :name => "Rob", :years => "28" }.assert_valid_keys(:name, :age) # => raises "ArgumentError: Unknown key(s): years"
{ :name => "Rob", :age => "28" }.assert_valid_keys("name", "age") # => raises "ArgumentError: Unknown key(s): name, age"
{ :name => "Rob", :age => "28" }.assert_valid_keys(:name, :age) # => passes, raises nothing

Returns a new hash with self and other_hash merged recursively.

Returns a new hash with self and other_hash merged recursively. Modifies the receiver in place.

Returns a hash that represents the difference between two hashes.

Examples:

{1 => 2}.diff(1 => 2)         # => {}
{1 => 2}.diff(1 => 3)         # => {1 => 2}
{}.diff(1 => 2)               # => {1 => 2}
{1 => 2, 3 => 4}.diff(1 => 2) # => {3 => 4}

Return a hash that includes everything but the given keys. This is useful for limiting a set of parameters to everything but a few known toggles:

@person.update_attributes(params[:person].except(:admin))

If the receiver responds to convert_key, the method is called on each of the arguments. This allows except to play nice with hashes with indifferent access for instance:

{:a => 1}.with_indifferent_access.except(:a)  # => {}
{:a => 1}.with_indifferent_access.except("a") # => {}

Replaces the hash without the given keys.

By default, only instances of Hash itself are extractable. Subclasses of Hash may implement this method and return true to declare themselves as extractable. If a Hash is extractable, Array#extract_options! pops it from the Array when it is the last element of the Array.

Allows for reverse merging two hashes where the keys in the calling hash take precedence over those in the other_hash. This is particularly useful for initializing an option hash with default values:

def setup(options = {})
  options.reverse_merge! :size => 25, :velocity => 10
end

Using merge, the above example would look as follows:

def setup(options = {})
  { :size => 25, :velocity => 10 }.merge(options)
end

The default :size and :velocity are only set if the options hash passed in doesn’t already have the respective key.

Performs the opposite of merge, with the keys and values from the first hash taking precedence over the second. Modifies the receiver in place.

Slice a hash to include only the given keys. This is useful for limiting an options hash to valid keys before passing to a method:

def search(criteria = {})
  assert_valid_keys(:mass, :velocity, :time)
end

search(options.slice(:mass, :velocity, :time))

If you have an array of keys you want to limit to, you should splat them:

valid_keys = [:mass, :velocity, :time]
search(options.slice(*valid_keys))

Replaces the hash with only the given keys. Returns a hash contained the removed key/value pairs

{:a => 1, :b => 2, :c => 3, :d => 4}.slice!(:a, :b) # => {:c => 3, :d =>4}

Return a new hash with all keys converted to strings.

Destructively convert all keys to strings.

Return a new hash with all keys converted to symbols, as long as they respond to to_sym.

Destructively convert all keys to symbols, as long as they respond to to_sym.

Converts a hash into a string suitable for use as a URL query string. An optional namespace can be passed to enclose the param names (see example below). The string pairs “key=value” that conform the query string are sorted lexicographically in ascending order.

Examples

{ :name => 'David', :nationality => 'Danish' }.to_param # => "name=David&nationality=Danish"

{ :name => 'David', :nationality => 'Danish' }.to_param('user') # => "user[name]=David&user[nationality]=Danish"

Returns a string containing an XML representation of its receiver:

{"foo" => 1, "bar" => 2}.to_xml
# =>
# <?xml version="1.0" encoding="UTF-8"?>
# <hash>
#   <foo type="integer">1</foo>
#   <bar type="integer">2</bar>
# </hash>

To do so, the method loops over the pairs and builds nodes that depend on the values. Given a pair key, value:

• If value is a hash there’s a recursive call with key as :root.

• If value is an array there’s a recursive call with key as :root, and key singularized as :children.

• If value is a callable object it must expect one or two arguments. Depending on the arity, the callable is invoked with the options hash as first argument with key as :root, and key singularized as second argument. Its return value becomes a new node.

• If value responds to to_xml the method is invoked with key as :root.

• Otherwise, a node with key as tag is created with a string representation of value as text node. If value is nil an attribute “nil” set to “true” is added. Unless the option :skip_types exists and is true, an attribute “type” is added as well according to the following mapping:

  XML_TYPE_NAMES = {
    "Symbol"     => "symbol",
    "Fixnum"     => "integer",
    "Bignum"     => "integer",
    "BigDecimal" => "decimal",
    "Float"      => "float",
    "TrueClass"  => "boolean",
    "FalseClass" => "boolean",
    "Date"       => "date",
    "DateTime"   => "datetime",
    "Time"       => "datetime"
  }

By default the root node is “hash”, but that’s configurable via the :root option.

The default XML builder is a fresh instance of Builder::XmlMarkup. You can configure your own builder with the :builder option. The method also accepts options like :dasherize and friends, they are forwarded to the builder.

Returns an +ActiveSupport::HashWithIndifferentAccess+ out of its receiver:

{:a => 1}.with_indifferent_access["a"] # => 1