Enables more predictable duck-typing on String-like classes. See Object#acts_like?.

Source: | on GitHub

# File activesupport/lib/active_support/core_ext/string/behavior.rb, line 5
def acts_like_string?
 true
end

If you pass a single integer, returns a substring of one character at that position. The first character of the string is at position 0, the next at position 1, and so on. If a range is supplied, a substring containing characters at offsets given by the range is returned. In both cases, if an offset is negative, it is counted from the end of the string. Returns nil if the initial offset falls outside the string. Returns an empty string if the beginning of the range is greater than the end of the string.

str = "hello"
str.at(0) # => "h"
str.at(1..3) # => "ell"
str.at(-2) # => "l"
str.at(-2..-1) # => "lo"
str.at(5) # => nil
str.at(5..-1) # => ""

If a Regexp is given, the matching portion of the string is returned. If a String is given, that given string is returned if it occurs in the string. In both cases, nil is returned if there is no match.

str = "hello"
str.at(/lo/) # => "lo"
str.at(/ol/) # => nil
str.at("lo") # => "lo"
str.at("ol") # => nil

Source: | on GitHub

# File activesupport/lib/active_support/core_ext/string/access.rb, line 29
def at(position)
 self[position]
end

A string is blank if it’s empty or contains whitespaces only:

''.blank? # => true
' '.blank? # => true
"\t\n\r".blank? # => true
' blah '.blank? # => false

Unicode whitespace is supported:

"\u00a0".blank? # => true

@return [true, false]

Source: | on GitHub

# File activesupport/lib/active_support/core_ext/object/blank.rb, line 153
def blank?
 # The regexp that matches blank strings is expensive. For the case of empty
 # strings we can speed up this method (~3.5x) with an empty? call. The
 # penalty for the rest of strings is marginal.
 empty? ||
 begin
 BLANK_RE.match?(self)
 rescue Encoding::CompatibilityError
 ENCODED_BLANKS[self.encoding].match?(self)
 end
end

By default, camelize converts strings to UpperCamelCase. If the argument to camelize is set to :lower then camelize produces lowerCamelCase.

camelize will also convert ‘/’ to ‘::’ which is useful for converting paths to namespaces.

'active_record'.camelize # => "ActiveRecord"
'active_record'.camelize(:lower) # => "activeRecord"
'active_record/errors'.camelize # => "ActiveRecord::Errors"
'active_record/errors'.camelize(:lower) # => "activeRecord::Errors"

See ActiveSupport::Inflector.camelize.

Source: | on GitHub

# File activesupport/lib/active_support/core_ext/string/inflections.rb, line 101
def camelize(first_letter = :upper)
 case first_letter
 when :upper
 ActiveSupport::Inflector.camelize(self, true)
 when :lower
 ActiveSupport::Inflector.camelize(self, false)
 else
 raise ArgumentError, "Invalid option, use either :upper or :lower."
 end
end

Creates a class name from a plural table name like Rails does for table names to models. Note that this returns a string and not a class. (To convert to an actual class follow classify with constantize.)

'ham_and_eggs'.classify # => "HamAndEgg"
'posts'.classify # => "Post"

See ActiveSupport::Inflector.classify.

Source: | on GitHub

# File activesupport/lib/active_support/core_ext/string/inflections.rb, line 239
def classify
 ActiveSupport::Inflector.classify(self)
end

constantize tries to find a declared constant with the name specified in the string. It raises a NameError when the name is not in CamelCase or is not initialized.

'Module'.constantize # => Module
'Class'.constantize # => Class
'blargle'.constantize # => NameError: wrong constant name blargle

See ActiveSupport::Inflector.constantize.

Source: | on GitHub

# File activesupport/lib/active_support/core_ext/string/inflections.rb, line 73
def constantize
 ActiveSupport::Inflector.constantize(self)
end

Replaces underscores with dashes in the string.

'puni_puni'.dasherize # => "puni-puni"

See ActiveSupport::Inflector.dasherize.

Source: | on GitHub

# File activesupport/lib/active_support/core_ext/string/inflections.rb, line 148
def dasherize
 ActiveSupport::Inflector.dasherize(self)
end

Removes the rightmost segment from the constant expression in the string.

'Net::HTTP'.deconstantize # => "Net"
'::Net::HTTP'.deconstantize # => "::Net"
'String'.deconstantize # => ""
'::String'.deconstantize # => ""
''.deconstantize # => ""

See ActiveSupport::Inflector.deconstantize.

See also demodulize.

Source: | on GitHub

# File activesupport/lib/active_support/core_ext/string/inflections.rb, line 177
def deconstantize
 ActiveSupport::Inflector.deconstantize(self)
end

Removes the module part from the constant expression in the string.

'ActiveSupport::Inflector::Inflections'.demodulize # => "Inflections"
'Inflections'.demodulize # => "Inflections"
'::Inflections'.demodulize # => "Inflections"
''.demodulize # => ''

See ActiveSupport::Inflector.demodulize.

See also deconstantize.

Source: | on GitHub

# File activesupport/lib/active_support/core_ext/string/inflections.rb, line 162
def demodulize
 ActiveSupport::Inflector.demodulize(self)
end

Converts the first character to lowercase.

'If they enjoyed The Matrix'.downcase_first # => "if they enjoyed The Matrix"
'I'.downcase_first # => "i"
''.downcase_first # => ""

See ActiveSupport::Inflector.downcase_first.

Source: | on GitHub

# File activesupport/lib/active_support/core_ext/string/inflections.rb, line 284
def downcase_first
 ActiveSupport::Inflector.downcase_first(self)
end

The inverse of String#include?. Returns true if the string does not include the other string.

"hello".exclude? "lo" # => false
"hello".exclude? "ol" # => true
"hello".exclude? ?h # => false

Source: | on GitHub

# File activesupport/lib/active_support/core_ext/string/exclude.rb, line 10
def exclude?(string)
 !include?(string)
end

Returns the first character. If a limit is supplied, returns a substring from the beginning of the string until it reaches the limit value. If the given limit is greater than or equal to the string length, returns a copy of self.

str = "hello"
str.first # => "h"
str.first(1) # => "h"
str.first(2) # => "he"
str.first(0) # => ""
str.first(6) # => "hello"

Source: | on GitHub

# File activesupport/lib/active_support/core_ext/string/access.rb, line 78
def first(limit = 1)
 self[0, limit] || raise(ArgumentError, "negative limit")
end

Creates a foreign key name from a class name. separate_class_name_and_id_with_underscore sets whether the method should put ‘_’ between the name and ‘id’.

'Message'.foreign_key # => "message_id"
'Message'.foreign_key(false) # => "messageid"
'Admin::Post'.foreign_key # => "post_id"

See ActiveSupport::Inflector.foreign_key.

Source: | on GitHub

# File activesupport/lib/active_support/core_ext/string/inflections.rb, line 297
def foreign_key(separate_class_name_and_id_with_underscore = true)
 ActiveSupport::Inflector.foreign_key(self, separate_class_name_and_id_with_underscore)
end

Returns a substring from the given position to the end of the string. If the position is negative, it is counted from the end of the string.

str = "hello"
str.from(0) # => "hello"
str.from(3) # => "lo"
str.from(-2) # => "lo"

You can mix it with to method and do fun things like:

str = "hello"
str.from(0).to(-1) # => "hello"
str.from(1).to(-2) # => "ell"

Source: | on GitHub

# File activesupport/lib/active_support/core_ext/string/access.rb, line 46
def from(position)
 self[position, length]
end

Marks a string as trusted safe. It will be inserted into HTML with no additional escaping performed. It is your responsibility to ensure that the string contains no malicious content. This method is equivalent to the raw helper in views. It is recommended that you use sanitize instead of this method. It should never be called on user input.

Source: | on GitHub

# File activesupport/lib/active_support/core_ext/string/output_safety.rb, line 225
def html_safe
 ActiveSupport::SafeBuffer.new(self)
end

Capitalizes the first word, turns underscores into spaces, and (by default) strips a trailing ‘_id’ if present. Like titleize, this is meant for creating pretty output.

The capitalization of the first word can be turned off by setting the optional parameter capitalize to false. By default, this parameter is true.

The trailing ‘_id’ can be kept and capitalized by setting the optional parameter keep_id_suffix to true. By default, this parameter is false.

'employee_salary'.humanize # => "Employee salary"
'author_id'.humanize # => "Author"
'author_id'.humanize(capitalize: false) # => "author"
'_id'.humanize # => "Id"
'author_id'.humanize(keep_id_suffix: true) # => "Author id"

See ActiveSupport::Inflector.humanize.

Source: | on GitHub

# File activesupport/lib/active_support/core_ext/string/inflections.rb, line 262
def humanize(capitalize: true, keep_id_suffix: false)
 ActiveSupport::Inflector.humanize(self, capitalize: capitalize, keep_id_suffix: keep_id_suffix)
end

Converts String to a TimeWithZone in the current zone if Time.zone or Time.zone_default is set, otherwise converts String to a Time via String#to_time

Source: | on GitHub

# File activesupport/lib/active_support/core_ext/string/zones.rb, line 9
def in_time_zone(zone = ::Time.zone)
 if zone
 ::Time.find_zone!(zone).parse(self)
 else
 to_time
 end
end

Indents the lines in the receiver:

<<EOS.indent(2)
def some_method
 some_code
end
EOS
# =>
 def some_method
 some_code
 end

The second argument, indent_string, specifies which indent string to use. The default is nil, which tells the method to make a guess by peeking at the first indented line, and fall back to a space if there is none.

" foo".indent(2) # => " foo"
"foo\n\t\tbar".indent(2) # => "\t\tfoo\n\t\t\t\tbar"
"foo".indent(2, "\t") # => "\t\tfoo"

While indent_string is typically one space or tab, it may be any string.

The third argument, indent_empty_lines, is a flag that says whether empty lines should be indented. Default is false.

"foo\n\nbar".indent(2) # => " foo\n\n bar"
"foo\n\nbar".indent(2, nil, true) # => " foo\n \n bar"

Source: | on GitHub

# File activesupport/lib/active_support/core_ext/string/indent.rb, line 42
def indent(amount, indent_string = nil, indent_empty_lines = false)
 dup.tap { |_| _.indent!(amount, indent_string, indent_empty_lines) }
end

Same as indent, except it indents the receiver in-place.

Returns the indented string, or nil if there was nothing to indent.

Source: | on GitHub

# File activesupport/lib/active_support/core_ext/string/indent.rb, line 7
def indent!(amount, indent_string = nil, indent_empty_lines = false)
 indent_string = indent_string || self[/^[ \t]/] || " "
 re = indent_empty_lines ? /^/ : /^(?!$)/
 gsub!(re, indent_string * amount)
end

Wraps the current string in the ActiveSupport::StringInquirer class, which gives you a prettier way to test for equality.

env = 'production'.inquiry
env.production? # => true
env.development? # => false

Source: | on GitHub

# File activesupport/lib/active_support/core_ext/string/inquiry.rb, line 13
def inquiry
 ActiveSupport::StringInquirer.new(self)
end

Returns true if string has utf_8 encoding.

utf_8_str = "some string".encode "UTF-8"
iso_str = "some string".encode "ISO-8859-1"
utf_8_str.is_utf8? # => true
iso_str.is_utf8? # => false

Source: | on GitHub

# File activesupport/lib/active_support/core_ext/string/multibyte.rb, line 48
def is_utf8?
 case encoding
 when Encoding::UTF_8, Encoding::US_ASCII
 valid_encoding?
 when Encoding::ASCII_8BIT
 dup.force_encoding(Encoding::UTF_8).valid_encoding?
 else
 false
 end
end

Returns the last character of the string. If a limit is supplied, returns a substring from the end of the string until it reaches the limit value (counting backwards). If the given limit is greater than or equal to the string length, returns a copy of self.

str = "hello"
str.last # => "o"
str.last(1) # => "o"
str.last(2) # => "lo"
str.last(0) # => ""
str.last(6) # => "hello"

Source: | on GitHub

# File activesupport/lib/active_support/core_ext/string/access.rb, line 92
def last(limit = 1)
 self[[length - limit, 0].max, limit] || raise(ArgumentError, "negative limit")
end

Multibyte proxy

mb_chars is a multibyte safe proxy for string methods.

It creates and returns an instance of the ActiveSupport::Multibyte::Chars class which encapsulates the original string. A Unicode safe version of all the String methods are defined on this proxy class. If the proxy class doesn’t respond to a certain method, it’s forwarded to the encapsulated string.

>> "lj".mb_chars.upcase.to_s
=> "LJ"

NOTE: Ruby 2.4 and later support native Unicode case mappings:

>> "lj".upcase
=> "LJ"

Method chaining

All the methods on the Chars proxy which normally return a string will return a Chars object. This allows method chaining on the result of any of these methods.

name.mb_chars.reverse.length # => 12

Interoperability and configuration

The Chars object tries to be as interchangeable with String objects as possible: sorting and comparing between String and Char work like expected. The bang! methods change the internal string representation in the Chars object. Interoperability problems can be resolved easily with a to_s call.

For more information about the methods defined on the Chars proxy see ActiveSupport::Multibyte::Chars. For information about how to change the default Multibyte behavior see ActiveSupport::Multibyte.

Source: | on GitHub

# File activesupport/lib/active_support/core_ext/string/multibyte.rb, line 37
def mb_chars
 ActiveSupport::Multibyte.proxy_class.new(self)
end

Replaces special characters in a string so that it may be used as part of a ‘pretty’ URL.

If the optional parameter locale is specified, the word will be parameterized as a word of that language. By default, this parameter is set to nil and it will use the configured I18n.locale.

class Person
 def to_param
 "#{id}-#{name.parameterize}"
 end
end
@person = Person.find(1)
# => #<Person id: 1, name: "Donald E. Knuth">
<%= link_to(@person.name, person_path) %>
# => <a href="/person/1-donald-e-knuth">Donald E. Knuth</a>

To preserve the case of the characters in a string, use the preserve_case argument.

class Person
 def to_param
 "#{id}-#{name.parameterize(preserve_case: true)}"
 end
end
@person = Person.find(1)
# => #<Person id: 1, name: "Donald E. Knuth">
<%= link_to(@person.name, person_path) %>
# => <a href="/person/1-Donald-E-Knuth">Donald E. Knuth</a>

See ActiveSupport::Inflector.parameterize.

Source: | on GitHub

# File activesupport/lib/active_support/core_ext/string/inflections.rb, line 215
def parameterize(separator: "-", preserve_case: false, locale: nil)
 ActiveSupport::Inflector.parameterize(self, separator: separator, preserve_case: preserve_case, locale: locale)
end

Returns the plural form of the word in the string.

If the optional parameter count is specified, the singular form will be returned if count == 1. For any other value of count the plural will be returned.

If the optional parameter locale is specified, the word will be pluralized as a word of that language. By default, this parameter is set to :en. You must define your own inflection rules for languages other than English.

'post'.pluralize # => "posts"
'octopus'.pluralize # => "octopi"
'sheep'.pluralize # => "sheep"
'words'.pluralize # => "words"
'the blue mailman'.pluralize # => "the blue mailmen"
'CamelOctopus'.pluralize # => "CamelOctopi"
'apple'.pluralize(1) # => "apple"
'apple'.pluralize(2) # => "apples"
'ley'.pluralize(:es) # => "leyes"
'ley'.pluralize(1, :es) # => "ley"

See ActiveSupport::Inflector.pluralize.

Source: | on GitHub

# File activesupport/lib/active_support/core_ext/string/inflections.rb, line 35
def pluralize(count = nil, locale = :en)
 locale = count if count.is_a?(Symbol)
 if count == 1
 dup
 else
 ActiveSupport::Inflector.pluralize(self, locale)
 end
end

Returns a new string with all occurrences of the patterns removed.

str = "foo bar test"
str.remove(" test") # => "foo bar"
str.remove(" test", /bar/) # => "foo "
str # => "foo bar test"

Source: | on GitHub

# File activesupport/lib/active_support/core_ext/string/filters.rb, line 32
def remove(*patterns)
 dup.remove!(*patterns)
end

Alters the string by removing all occurrences of the patterns.

str = "foo bar test"
str.remove!(" test", /bar/) # => "foo "
str # => "foo "

Source: | on GitHub

# File activesupport/lib/active_support/core_ext/string/filters.rb, line 40
def remove!(*patterns)
 patterns.each do |pattern|
 gsub! pattern, ""
 end
 self
end

safe_constantize tries to find a declared constant with the name specified in the string. It returns nil when the name is not in CamelCase or is not initialized.

'Module'.safe_constantize # => Module
'Class'.safe_constantize # => Class
'blargle'.safe_constantize # => nil

See ActiveSupport::Inflector.safe_constantize.

Source: | on GitHub

# File activesupport/lib/active_support/core_ext/string/inflections.rb, line 86
def safe_constantize
 ActiveSupport::Inflector.safe_constantize(self)
end

The reverse of pluralize, returns the singular form of a word in a string.

If the optional parameter locale is specified, the word will be singularized as a word of that language. By default, this parameter is set to :en. You must define your own inflection rules for languages other than English.

'posts'.singularize # => "post"
'octopi'.singularize # => "octopus"
'sheep'.singularize # => "sheep"
'word'.singularize # => "word"
'the blue mailmen'.singularize # => "the blue mailman"
'CamelOctopi'.singularize # => "CamelOctopus"
'leyes'.singularize(:es) # => "ley"

See ActiveSupport::Inflector.singularize.

Source: | on GitHub

# File activesupport/lib/active_support/core_ext/string/inflections.rb, line 60
def singularize(locale = :en)
 ActiveSupport::Inflector.singularize(self, locale)
end

Returns the string, first removing all whitespace on both ends of the string, and then changing remaining consecutive whitespace groups into one space each.

Note that it handles both ASCII and Unicode whitespace.

%{ Multi-line
 string }.squish # => "Multi-line string"
" foo bar \n \t boo".squish # => "foo bar boo"

Source: | on GitHub

# File activesupport/lib/active_support/core_ext/string/filters.rb, line 13
def squish
 dup.squish!
end

Performs a destructive squish. See String#squish.

str = " foo bar \n \t boo"
str.squish! # => "foo bar boo"
str # => "foo bar boo"

Source: | on GitHub

# File activesupport/lib/active_support/core_ext/string/filters.rb, line 21
def squish!
 gsub!(/[[:space:]]+/, " ")
 strip!
 self
end

Strips indentation in heredocs.

For example in

if options[:usage]
 puts <<-USAGE.strip_heredoc
 This command does such and such.
 Supported options are:
 -h This message
 ...
 USAGE
end

the user would see the usage message aligned against the left margin.

Technically, it looks for the least indented non-empty line in the whole string, and removes that amount of leading whitespace.

Source: | on GitHub

# File activesupport/lib/active_support/core_ext/string/strip.rb, line 22
def strip_heredoc
 gsub(/^#{scan(/^[ \t]*(?=\S)/).min}/, "").tap do |stripped|
 stripped.freeze if frozen?
 end
end

Creates the name of a table like Rails does for models to table names. This method uses the pluralize method on the last word in the string.

'RawScaledScorer'.tableize # => "raw_scaled_scorers"
'ham_and_egg'.tableize # => "ham_and_eggs"
'fancyCategory'.tableize # => "fancy_categories"

See ActiveSupport::Inflector.tableize.

Source: | on GitHub

# File activesupport/lib/active_support/core_ext/string/inflections.rb, line 227
def tableize
 ActiveSupport::Inflector.tableize(self)
end

Capitalizes all the words and replaces some characters in the string to create a nicer looking title. titleize is meant for creating pretty output. It is not used in the Rails internals.

The trailing ‘_id’,‘Id’.. can be kept and capitalized by setting the optional parameter keep_id_suffix to true. By default, this parameter is false.

'man from the boondocks'.titleize # => "Man From The Boondocks"
'x-men: the last stand'.titleize # => "X Men: The Last Stand"
'string_ending_with_id'.titleize(keep_id_suffix: true) # => "String Ending With Id"

See ActiveSupport::Inflector.titleize.

Source: | on GitHub

# File activesupport/lib/active_support/core_ext/string/inflections.rb, line 126
def titleize(keep_id_suffix: false)
 ActiveSupport::Inflector.titleize(self, keep_id_suffix: keep_id_suffix)
end

Returns a substring from the beginning of the string to the given position. If the position is negative, it is counted from the end of the string.

str = "hello"
str.to(0) # => "h"
str.to(3) # => "hell"
str.to(-2) # => "hell"

You can mix it with from method and do fun things like:

str = "hello"
str.from(0).to(-1) # => "hello"
str.from(1).to(-2) # => "ell"

Source: | on GitHub

# File activesupport/lib/active_support/core_ext/string/access.rb, line 63
def to(position)
 position += size if position < 0
 self[0, position + 1] || +""
end

Converts a string to a Date value.

"1-1-2012".to_date # => 2012年1月01日
"01/01/2012".to_date # => 2012年1月01日
"2012年12月13日".to_date # => 2012年12月13日
"12/13/2012".to_date # => ArgumentError: invalid date

Source: | on GitHub

# File activesupport/lib/active_support/core_ext/string/conversions.rb, line 47
def to_date
 ::Date.parse(self, false) unless blank?
end

Converts a string to a DateTime value.

"1-1-2012".to_datetime # => 2012年1月01日 00:00:00 +0000
"01/01/2012 23:59:59".to_datetime # => 2012年1月01日 23:59:59 +0000
"2012年12月13日 12:50".to_datetime # => 2012年12月13日 12:50:00 +0000
"12/13/2012".to_datetime # => ArgumentError: invalid date

Source: | on GitHub

# File activesupport/lib/active_support/core_ext/string/conversions.rb, line 57
def to_datetime
 ::DateTime.parse(self, false) unless blank?
end

Converts a string to a Time value. The form can be either :utc or :local (default :local).

The time is parsed using Time.parse method. If form is :local, then the time is in the system timezone. If the date part is missing then the current date is used and if the time part is missing then it is assumed to be 00:00:00.

"13-12-2012".to_time # => 2012年12月13日 00:00:00 +0100
"06:12".to_time # => 2012年12月13日 06:12:00 +0100
"2012年12月13日 06:12".to_time # => 2012年12月13日 06:12:00 +0100
"2012年12月13日T06:12".to_time # => 2012年12月13日 06:12:00 +0100
"2012年12月13日T06:12".to_time(:utc) # => 2012年12月13日 06:12:00 UTC
"12/13/2012".to_time # => ArgumentError: argument out of range
"1604326192".to_time # => ArgumentError: argument out of range

Source: | on GitHub

# File activesupport/lib/active_support/core_ext/string/conversions.rb, line 22
def to_time(form = :local)
 parts = Date._parse(self, false)
 used_keys = %i(year mon mday hour min sec sec_fraction offset)
 return if !parts.keys.intersect?(used_keys)
 now = Time.now
 time = Time.new(
 parts.fetch(:year, now.year),
 parts.fetch(:mon, now.month),
 parts.fetch(:mday, now.day),
 parts.fetch(:hour, 0),
 parts.fetch(:min, 0),
 parts.fetch(:sec, 0) + parts.fetch(:sec_fraction, 0),
 parts.fetch(:offset, form == :utc ? 0 : nil)
 )
 form == :utc ? time.utc : time.to_time
end

Truncates a given text to length truncate_to if text is longer than truncate_to:

'Once upon a time in a world far far away'.truncate(27)
# => "Once upon a time in a wo..."

Pass a string or regexp :separator to truncate text at a natural break:

'Once upon a time in a world far far away'.truncate(27, separator: ' ')
# => "Once upon a time in a..."
'Once upon a time in a world far far away'.truncate(27, separator: /\s/)
# => "Once upon a time in a..."

The last characters will be replaced with the :omission string (defaults to "..."). The total length will not exceed truncate_to unless both text and :omission are longer than truncate_to:

'And they found that many people were sleeping better.'.truncate(25, omission: '... (continued)')
# => "And they f... (continued)"
'And they found that many people were sleeping better.'.truncate(4, omission: '... (continued)')
# => "... (continued)"

Source: | on GitHub

# File activesupport/lib/active_support/core_ext/string/filters.rb, line 70
def truncate(truncate_to, options = {})
 return dup unless length > truncate_to
 omission = options[:omission] || "..."
 length_with_room_for_omission = truncate_to - omission.length
 stop = \
 if options[:separator]
 rindex(options[:separator], length_with_room_for_omission) || length_with_room_for_omission
 else
 length_with_room_for_omission
 end
 +"#{self[0, stop]}#{omission}"
end

Truncates text to at most truncate_to bytes in length without breaking string encoding by splitting multibyte characters or breaking grapheme clusters ("perceptual characters") by truncating at combining characters.

>> "🔪🔪🔪🔪🔪🔪🔪🔪🔪🔪🔪🔪🔪🔪🔪🔪🔪🔪🔪🔪".size
=> 20
>> "🔪🔪🔪🔪🔪🔪🔪🔪🔪🔪🔪🔪🔪🔪🔪🔪🔪🔪🔪🔪".bytesize
=> 80
>> "🔪🔪🔪🔪🔪🔪🔪🔪🔪🔪🔪🔪🔪🔪🔪🔪🔪🔪🔪🔪".truncate_bytes(20)
=> "🔪🔪🔪🔪..."

The truncated text ends with the :omission string, defaulting to "...", for a total length not exceeding truncate_to.

Raises ArgumentError when the bytesize of :omission exceeds truncate_to.

Source: | on GitHub

# File activesupport/lib/active_support/core_ext/string/filters.rb, line 101
def truncate_bytes(truncate_to, omission: "...")
 omission ||= ""
 case
 when bytesize <= truncate_to
 dup
 when omission.bytesize > truncate_to
 raise ArgumentError, "Omission #{omission.inspect} is #{omission.bytesize}, larger than the truncation length of #{truncate_to} bytes"
 when omission.bytesize == truncate_to
 omission.dup
 else
 self.class.new.force_encoding(encoding).tap do |cut|
 cut_at = truncate_to - omission.bytesize
 each_grapheme_cluster do |grapheme|
 if cut.bytesize + grapheme.bytesize <= cut_at
 cut << grapheme
 else
 break
 end
 end
 cut << omission
 end
 end
end

Truncates a given text after a given number of words (words_count):

'Once upon a time in a world far far away'.truncate_words(4)
# => "Once upon a time..."

Pass a string or regexp :separator to specify a different separator of words:

'Once<br>upon<br>a<br>time<br>in<br>a<br>world'.truncate_words(5, separator: '<br>')
# => "Once<br>upon<br>a<br>time<br>in..."

The last characters will be replaced with the :omission string (defaults to "..."):

'And they found that many people were sleeping better.'.truncate_words(5, omission: '... (continued)')
# => "And they found that many... (continued)"

Source: | on GitHub

# File activesupport/lib/active_support/core_ext/string/filters.rb, line 142
def truncate_words(words_count, options = {})
 sep = options[:separator] || /\s+/
 sep = Regexp.escape(sep.to_s) unless Regexp === sep
 if self =~ /\A((?>.+?#{sep}){#{words_count - 1}}.+?)#{sep}.*/m
 1ドル + (options[:omission] || "...")
 else
 dup
 end
end

The reverse of camelize. Makes an underscored, lowercase form from the expression in the string.

underscore will also change ‘::’ to ‘/’ to convert namespaces to paths.

'ActiveModel'.underscore # => "active_model"
'ActiveModel::Errors'.underscore # => "active_model/errors"

See ActiveSupport::Inflector.underscore.

Source: | on GitHub

# File activesupport/lib/active_support/core_ext/string/inflections.rb, line 139
def underscore
 ActiveSupport::Inflector.underscore(self)
end

Converts the first character to uppercase.

'what a Lovely Day'.upcase_first # => "What a Lovely Day"
'w'.upcase_first # => "W"
''.upcase_first # => ""

See ActiveSupport::Inflector.upcase_first.

Source: | on GitHub

# File activesupport/lib/active_support/core_ext/string/inflections.rb, line 273
def upcase_first
 ActiveSupport::Inflector.upcase_first(self)
end