README.md
# ActiveDynamic
[](https://badge.fury.io/rb/active_dynamic)
[](https://codeclimate.com/github/koss-lebedev/active_dynamic)
[](https://travis-ci.org/koss-lebedev/active_dynamic)
ActiveDynamic allows to dynamically add properties to your ActiveRecord models and
work with them as regular properties.
To see this in practice, check out the demo application available at [https://github.com/koss-lebedev/active_dynamic_demo](https://github.com/koss-lebedev/active_dynamic_demo).
I also wrote [an article](https://medium.com/@koss_lebedev/how-to-dynamically-add-attributes-to-your-activerecord-models-e233b17ad695#.k66n002of) explaining how to use active_dynamic.
## Installation
Add this line to your application's Gemfile:
```ruby
gem 'active_dynamic'
```
And then execute:
$ bundle
Or install it yourself as:
$ gem install active_dynamic
## Usage
To make this gem work, first you need to add `has_dynamic_attributes` to the model that needs to have dynamic
attributes. For example, if you have `Profile` model:
```ruby
class Profile < ActiveRecord::Base
has_dynamic_attributes
# ...
end
```
After that you need to set a class that will resolve definitions of the dynamic attributes to be created on `Profile` model:
```ruby
# lib/initializers/dynamic_attribute.rb
ActiveDynamic.configure do |config|
config.provider_class = ProfileAttributeProvider
end
class ProfileAttributeProvider
# Constructor will receive an instance to which dynamic attributes are added
def initialize(model)
@model = model
end
# This method has to return array of dynamic field definitions.
# You can get it from the configuration file, DB, etc., depending on your app logic
def call
[
# attribute definition has to specify attribute display name
ActiveDynamic::AttributeDefinition.new('biography'),
# Optionally you can provide datatype, system name, and default value.
# If system name is not specified, it will be generated automatically from display name
ActiveDynamic::AttributeDefinition.new('age', datatype: ActiveDynamic::DataType::Integer, default_value: 18)
]
end
end
```
To resolve dynamic attribute definitions for more than one model:
```ruby
class Profile < ActiveRecord::Base
has_dynamic_attributes
# ...
end
class Document < ActiveRecord::Base
has_dynamic_attributes
# ...
end
class ProfileAttributeProvider
def initialize(model)
@model = model
end
def call
case @model
when Profile
[
# attribute definitions for Profile model
]
when Document
[
# attribute definitions for Document model
]
else
[]
end
end
end
```
## How ActiveDynamic resolves dynamic attributes
When you work with unsaved models, ActiveDynamic will use `provider_class` to resolve a list
of dynamic attributes, and it will store them alongside the model when the model is saved.
So next time when you load that model from DB, ActiveDynamic won't look into `provider_class`
and it will load only the dynamic attributes that were created when the model was saved for
the first time.
If you want dynamic attributes to be resolved from `provider_class` for persisted models as well,
you can use `resolve_persisted` configuration option:
```ruby
# lib/initializers/dynamic_attribute.rb
ActiveDynamic.configure do |config|
# ...
# you can set it to Bool value to apply the behavior to all models
config.resolve_persisted = true
# or you can set it to a Proc to configure the behavior on per-class basis
config.resolve_persisted = Proc.new { |model| model.is_a?(Profile) ? true : false }
end
```
## Querying
**This is still work in progress, so think twice before using it in production 🙂**
ActiveDynamic provides `where_dynamic` class method, that you can use to search by dynamic fields. For example, if you have a `Profile` model with `age` attribute, you can use it like this:
```ruby
Profile.where_dynamic(age: 21)
```
At the moment, only hash arguments are supported.
## Contributing
Bug reports and pull requests are welcome on GitHub at https://github.com/koss-lebedev/active_dynamic. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the [Contributor Covenant](http://contributor-covenant.org) code of conduct.
## License
The gem is available as open source under the terms of the [MIT License](http://opensource.org/licenses/MIT).