Intresting String inflections in rails

* camelcase
* camelize
* classify
* constantize
* dasherize
* demodulize
* foreign_key
* humanize
* parameterize
* pluralize
* singularize
* tableize
* titlecase
* titleize
* underscore

camelcase(first_letter = :upper)

Alias for camelize
camelize(first_letter = :upper)

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”

This method is also aliased as camelcase


Create 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.)

“egg_and_hams”.classify # => “EggAndHam”
“posts”.classify # => “Post”

Singular names are not handled correctly.

“business”.classify # => “Busines”


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


Replaces underscores with dashes in the string.

“puni_puni” # => “puni-puni”


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

“ActiveRecord::CoreExtensions::String::Inflections”.demodulize # => “Inflections”
“Inflections”.demodulize # => “Inflections”

foreign_key(separate_class_name_and_id_with_underscore = true)

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”


Capitalizes the first word, turns underscores into spaces, and strips ‘_id’. Like titleize, this is meant for creating pretty output.

“employee_salary” # => “Employee salary”
“author_id” # => “Author”


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

class Person
def to_param

@person = Person.find(1)
# => #

# => Donald E. Knuth


Returns the plural form of the word in the string.

“post”.pluralize # => “posts”
“octopus”.pluralize # => “octopi”
“sheep”.pluralize # => “sheep”
“words”.pluralize # => “words”
“the blue mailman”.pluralize # => “the blue mailmen”
“CamelOctopus”.pluralize # => “CamelOctopi”


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

“posts”.singularize # => “post”
“octopi”.singularize # => “octopus”
“sheep”.singularize # => “sheep”
“word”.singularize # => “word”
“the blue mailmen”.singularize # => “the blue mailman”
“CamelOctopi”.singularize # => “CamelOctopus”


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”
“egg_and_ham”.tableize # => “egg_and_hams”
“fancyCategory”.tableize # => “fancy_categories”


Alias for titleize

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.

titleize is also aliased as titlecase.

“man from the boondocks”.titleize # => “Man From The Boondocks”
“x-men: the last stand”.titleize # => “X Men: The Last Stand”

This method is also aliased as titlecase


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.

“ActiveRecord”.underscore # => “active_record”
“ActiveRecord::Errors”.underscore # => active_record/errors

One thought on “Intresting String inflections in rails

  1. Remove special characters from string "STRING"..gsub(/[^a-zA-Z 0-9]/, "")# escape special chars before save def before_save[^a-zA-Z 0-9]/, "") end

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