Nameerror uninitialized constant

The nameerror uninitialized constant is an error message that occurs when you are working with Ruby.

If you’re struggling to fix this error don’t worry, we’ve got your back.

In this article, we are going to show how to fix the nameerror: uninitialized constant error message.

What is “nameerror uninitialized constant”?

The nameerror: uninitialized constant error message occurs when you try to reference a variable or a constant, such as a module, a class, or a constant variable that has not been defined or initialized.

For example:

class MyClass
  def my_method
    puts MY_CONSTANT
  end
end

MyClass.new.my_method

This example code will result to:

NameError: uninitialized constant

A constant is a value that does not change throughout the execution of a program. In Ruby, constants are defined using uppercase letters.

Why does this error occur?

This nameerror uninitialized constant can occur due to some reasons that include the following:

❌ Misspelling the constant name.

❌ Referencing the constant before it is defined.

❌ Defining the constant in the wrong scope.

❌ Loading files in the wrong order.

How to fix “nameerror uninitialized constant”?

Here are the following solutions that will help you to fix the error.

1. Specify the missing constant

To fix the error you just have to specify the missing constant.

This can be done by declaring the constant at the appropriate scope, such as at the top level of the program or inside a class or module.

For example:

Sample_CONSTANT = "Hi!, welcome to itsourcecode!"

class MyClass
  def my_method
    puts Sample_CONSTANT
  end
end

MyClass.new.my_method

As you can see, we define the constant Sample_CONSTANT at the top level of the program and use it inside the MyClass class.

Output:

Hi!, welcome to itsourcecode!

2. Use a string instead of a constant

Another effective solution is to use a string instead of a constant. This can be useful if the constant is not defined anywhere in the code but we still need to use its value.

class MyClass
  def my_method
    puts "Hi!, welcome to itsourcecode!"
  end
end

MyClass.new.my_method

As you have notice in this example, we replace the missing constant with a string “Hi!, welcome to itsourcecode!” When we run the code, it prints the string to the console.

Output:

Hi!, welcome to itsourcecode!

3. Check for typos

This error caused by a simple typo in the constant name. In order to resolve it , You have to double-check the spelling of the constant name and ensure it matches the name used in the code.

Conclusion

The nameerror: uninitialized constant error message occurs when you try to reference a variable or a constant, such as a module, a class, or a constant variable that has not been defined or initialized.

This article already provides solutions for this error to help you fix the error message.

You could also check out other “nameerror” articles that may help you in the future if you encounter them.

• Nameerror: name ‘null’ is not defined
• Nameerror: name ‘xrange’ is not defined
• Nameerror name df is not defined

Hoping that this article helps you fix the error. Thank you for reading itsourcecoders 😊