README.md
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# Nested Validator
Nested validations allow a parent's class validity to include those of child
attributes. Errors messages will be copied from the child attribute to the parent.
## Installation
Add this line to your application's Gemfile:
gem 'nested_validator'
And then execute:
$ bundle
Or install it yourself as:
$ gem install nested_validator
## Usage
Assume we have a parent object and we want its validaty to depend on its child validity:
``` ruby
class ParentBase
include ActiveModel::Validations
attr_accessor :child
def initialize
self.child = Child.new
end
end
class Child
include ActiveModel::Validations
attr_accessor :attribute1, :attribute2
validates :attribute1, presence: true
validates :attribute2, presence: true
end
```
Well, we can use a nested validation to do just that:
``` ruby
class Parent < ParentBase
validates :child, nested: true
end
parent = Parent.new
parent.valid?
puts parent.errors.messages
# => {:"child attribute1"=>["can't be blank"], :"child attribute2"=>["can't be blank"]}
```
### What if I want to validate with just some of the child attributes?
You can use an ```only``` option like this:
``` ruby
class ParentOnly < ParentBase
validates :child, nested: { only: :attribute1 }
end
parent = ParentOnly.new
parent.valid?
puts parent.errors.messages
# => {:"child attribute1"=>["can't be blank"]}
```
You can also provide an array of attributes to ```only``` if you want to include more than one.
### OK, is there a way to exclude some child attributes?
Sure thing. You can use the ```except``` option:
``` ruby
class ParentExcept < ParentBase
validates :child, nested: { except: :attribute2 }
end
parent = ParentExcept.new
parent.valid?
puts parent.errors.messages
# => {:"child attribute1"=>["can't be blank"]}
```
### OK, is there a way to require one of several attributes?
Yes. You can use the ```any``` option which requires that at least
one of the specified child attributes is valid:
``` ruby
class ParentExcept < ParentBase
validates :child, nested: { any: [:attribute1, :attribute2] }
end
parent = ParentExcept.new
parent.valid?
puts parent.errors.messages
# => {:"child attribute1"=>["can't be blank"], :"child attribute2"=>["can't be blank"]}
```
### Alright, what if I want a custom message?
You can specify a ```prefix``` instead of the child's attribute name:
``` ruby
class ParentPrefix < ParentBase
validates :child, nested: { only: :attribute1, prefix: 'OMG'}
end
parent = ParentPrefix.new
parent.valid?
puts parent.errors.messages
# => {:"OMG attribute1"=>["can't be blank"]}
```
### What happens if the child is an Array or Hash?
In this case, each value in the array or hash will be validated and the error message will
include the index or key of the value.
For an array:
``` ruby
class ParentArray < ParentBase
validates :child, nested: { only: :attribute1 }
end
parent = ParentArray.new
parent.child = [Child.new] * 2
parent.valid?
puts parent.errors.messages
# => {:"child[0] attribute1"=>["can't be blank"], :"child[1] attribute1"=>["can't be blank"]}
```
For a hash:
``` ruby
class ParentHash < ParentBase
validates :child, nested: { only: :attribute1 }
end
parent = ParentHash.new
parent.child = { thing1: Child.new, thing2: Child.new }
parent.valid?
puts parent.errors.messages
# => {:"child[thing1] attribute1"=>["can't be blank"], :"child[thing2] attribute1"=>["can't be blank"]}
```
### Can I easily use this for multiple child attributes?
You can use the ```validates_nested``` method:
``` ruby
class ParentMultiple < ParentBase
attr_accessor :child2
validate_nested :child, :child2, only: :attribute1
def initialize
self.child = Child.new
self.child2 = Child.new
end
end
parent = ParentMultiple.new
parent.valid?
puts parent.errors.messages
# => {:"child attribute1"=>["can't be blank"], :"child2 attribute1"=>["can't be blank"]}
```
## Testing With RSpec
When you ```require nested_validator``` you will have access to the RSpec matcher ```validate_nested```
that you can use in your specs.
Here are some examples:
``` ruby
describe Parent do
it { should validate_nested(:child) }
it { should validate_nested(:child).with_prefix(:thing1) }
it { should validate_nested(:child).only(:attribute1) }
it { should validate_nested(:child).only(:attribute1, :attribute2) }
it { should validate_nested(:child).except(:attribute1) }
it { should validate_nested(:child).except(:attribute1, :attribute2) }
it { should validate_nested(:child).any(:attribute1, :attribute2) }
end
```
## Contributing
1. Fork it ( https://github.com/dwhelan/nested_validator/fork )
2. Create your feature branch (`git checkout -b my-new-feature`)
3. Commit your changes (`git commit -am 'Add some feature'`)
4. Push to the branch (`git push origin my-new-feature`)
5. Create a new Pull Request