docs/general/deserialization.md
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# Deserialization
This is currently an *experimental* feature. The interface may change.
## JSON API
The `ActiveModelSerializers::Deserialization` defines two methods (namely `jsonapi_parse` and `jsonapi_parse!`), which take a `Hash` or an instance of `ActionController::Parameters` representing a JSON API payload, and return a hash that can directly be used to create/update models. The bang version throws an `InvalidDocument` exception when parsing fails, whereas the "safe" version simply returns an empty hash.
- Parameters
- document: `Hash` or `ActionController::Parameters` instance
- options:
- only: `Array` of whitelisted fields
- except: `Array` of blacklisted fields
- keys: `Hash` of fields the name of which needs to be modified (e.g. `{ :author => :user, :date => :created_at }`)
Examples:
```ruby
class PostsController < ActionController::Base
def create
Post.create(create_params)
end
def create_params
ActiveModelSerializers::Deserialization.jsonapi_parse(params, only: [:title, :content, :author])
end
end
```
Given a JSON API document,
```
document = {
'data' => {
'id' => 1,
'type' => 'post',
'attributes' => {
'title' => 'Title 1',
'date' => '2015-12-20'
},
'relationships' => {
'author' => {
'data' => {
'type' => 'user',
'id' => '2'
}
},
'second_author' => {
'data' => nil
},
'comments' => {
'data' => [{
'type' => 'comment',
'id' => '3'
},{
'type' => 'comment',
'id' => '4'
}]
}
}
}
}
```
The entire document can be parsed without specifying any options:
```ruby
ActiveModelSerializers::Deserialization.jsonapi_parse(document)
#=>
# {
# title: 'Title 1',
# date: '2015-12-20',
# author_id: 2,
# second_author_id: nil
# comment_ids: [3, 4]
# }
```
and fields, relationships, and polymorphic relationships can be specified via the options:
```ruby
ActiveModelSerializers::Deserialization
.jsonapi_parse(document, only: [:title, :date, :author],
keys: { date: :published_at },
polymorphic: [:author])
#=>
# {
# title: 'Title 1',
# published_at: '2015-12-20',
# author_id: '2',
# author_type: 'user'
# }
```
## Attributes/Json
There is currently no deserialization for those adapters.