module ENV

Overview

ENV is a hash-like accessor for environment variables.

Example

# Set env var PORT to a default if not already set
ENV["PORT"] ||= "5000"
# Later use that env var.
puts ENV["PORT"].to_i

NOTE All keys and values are strings. You must take care to cast other types at runtime, e.g. integer port numbers.

Extended Modules

Enumerable({String, String})

Defined in:

env.cr

Class Method Summary

.[](key : String) : String
Retrieves the value for environment variable namedkey as aString.
.[]=(key : String, value : String | Nil)
Sets the value for environment variable namedkey asvalue.
.[]?(key : String) : String | Nil
Retrieves the value for environment variable namedkey as aString?.
.clear : Nil
.delete(key : String) : String | Nil
Removes the environment variable namedkey.
.each(& : Tuple(String, String) -> )
Iterates over allKEY=VALUE pairs of environment variables, yielding both thekey andvalue.
.fetch(key, default : T) : String | T forall T
Retrieves a value corresponding to the givenkey.
.fetch(key) : String
Retrieves a value corresponding to the givenkey.
.fetch(key : String, &block : String -> T) : String | T forall T
Retrieves a value corresponding to a givenkey.
.has_key?(key : String) : Bool
Returnstrue if the environment variable namedkey exists andfalse if it doesn't.
.inspect(io)
Writes the contents of the environment toio.
.keys : Array(String)
Returns an array of all the environment variable names.
.pretty_print(pp)
.values : Array(String)
Returns an array of all the environment variable values.

Class Method Detail

def self.[](key : String) : String #

Retrieves the value for environment variable namedkey as aString. RaisesKeyError if the named variable does not exist.

def self.[]=(key : String, value : String | Nil) #

Sets the value for environment variable namedkey asvalue. Overwrites existing environment variable if already present. Returnsvalue if successful, otherwise raises an exception. Ifvalue isnil, the environment variable is deleted.

Ifkey orvalue contains a null-byte anArgumentError is raised.

def self.[]?(key : String) : String | Nil #

Retrieves the value for environment variable namedkey as aString?. Returnsnil if the named variable does not exist.

def self.clear : Nil #

def self.delete(key : String) : String | Nil #

Removes the environment variable namedkey. Returns the previous value if the environment variable existed, otherwise returnsnil.

def self.each(& : Tuple(String, String) -> ) #

Iterates over allKEY=VALUE pairs of environment variables, yielding both thekey andvalue.

ENV.each do |key, value|
  puts "#{key} => #{value}"
end

def self.fetch(key, default : T) : String | T forall T #

Retrieves a value corresponding to the givenkey. Return the second argument's value if thekey does not exist.

def self.fetch(key) : String #

Retrieves a value corresponding to the givenkey. Raises aKeyError exception if the key does not exist.

def self.fetch(key : String, &block : String -> T) : String | T forall T #

Retrieves a value corresponding to a givenkey. Return the value of the block if thekey does not exist.

def self.has_key?(key : String) : Bool #

Returnstrue if the environment variable namedkey exists andfalse if it doesn't.

ENV.has_key?("NOT_A_REAL_KEY") # => false
ENV.has_key?("PATH")           # => true

def self.inspect(io) #

Writes the contents of the environment toio.

def self.keys : Array(String) #

Returns an array of all the environment variable names.

def self.pretty_print(pp) #

def self.values : Array(String) #

Returns an array of all the environment variable values.