Fix Validation Errors

This guide helps you diagnose and fix validation errors.

Check What's Invalid

user = User.new("", "invalid-email")

unless user.valid?
  user.errors.each do |error|
    puts "#{error.field}: #{error.message}"
  end
end

Common Error: Presence Validation Failed

Error:

name: can't be blank

Cause: Field is empty or nil.

Solutions:

1. Provide a value:

user = User.new("John", "[e-mail]")  # Not empty

1. If field should be optional, adjust validation:

# Remove presence validation or make it conditional
validate :bio, presence: true, on: :update

Common Error: Format Validation Failed

Error:

email: is invalid

Cause: Value doesn't match the required format.

Solutions:

1. Fix the value:

user.email = "[e-mail]"  # Valid email format

1. Check the regex pattern:

# Make sure pattern matches expected format
validate :email, match: /\A[\w+\-.]+@[a-z\d\-.]+\.[a-z]+\z/i

Common Error: Size Validation Failed

Error:

username: is too short (minimum is 3 characters)

Solutions:

1. Provide longer value:

user.username = "john"  # At least 3 characters

1. Adjust size requirement if too strict:

validate :username, size: 2..50  # Allow shorter names

Common Error: Uniqueness Validation Failed

Error:

email: has already been taken

Cause: Another record has the same value.

Solutions:

1. Use a different value:

user.email = "[e-mail]"

1. Find and handle the existing record:

existing = User.find_by(email: email)
if existing
  # Handle duplicate - update existing or reject
end

Common Error: Numeric Validation Failed

Error:

age: must be greater than 0

Solutions:

1. Provide valid number:

user.age = 25  # Positive number

1. Check validation constraints:

validate :age, gt: 0, lt: 150

Debugging Validation

Print all errors with details:

user = User.new("", "bad", -5)

if user.valid?
  puts "Valid!"
else
  puts "Validation failed:"
  puts "Errors count: #{user.errors.size}"

  user.errors.each do |error|
    puts "  Field: #{error.field}"
    puts "  Message: #{error.message}"
    puts ""
  end
end

Skip Validation (Use Carefully)

Sometimes you need to bypass validation:

# Direct database update bypasses model validation
User.where(id: 1).update!(email: "[e-mail]")

Test Validations

describe User do
  it "requires a name" do
    user = User.new("", "[e-mail]")
    user.valid?.should be_false
    user.errors.map(&.field).should contain(:name)
  end

  it "requires valid email format" do
    user = User.new("John", "invalid")
    user.valid?.should be_false
    user.errors.map(&.field).should contain(:email)
  end

  it "accepts valid data" do
    user = User.new("John", "[e-mail]")
    user.valid?.should be_true
  end
end

Handle Validation in Controllers

def create(params)
  user = User.new(params[:name], params[:email])

  if user.save
    {status: "success", user: user.to_json}
  else
    {
      status: "error",
      errors: user.errors.map { |e| {field: e.field, message: e.message} }
    }
  end
end

Custom Error Messages

Make errors user-friendly:

validate :email, required: true, message: "Please provide your email address"
validate :password, size: 8..100, message: "Password must be at least 8 characters"

Related

• Add Validations

• Validation Options Reference

• Create Records