Easy FHIR Persistence with FireKit for iOS - FHIR DevDays · Summary •FireKit •Provides a...

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Easy FHIR Persistence with FireKit for iOS

Ryan Baldwin, eHealth Innovation @ University Health Network

About Me

• Name: Ryan Baldwin

• Background• Software Developer of 16 years

• Accidentally created • FireKit

• Restivus

• Author • Clojure Web Development Essentials

• Hates Shaving

Quick Assessment

• Who here knows FHIR?

• Who here knows Realm?

• Good news!• Familiarity is beneficial, but not required

• However, you should be familiar with • Swift

Agenda

• Origin Story

• What FireKit can do

• What FireKit cannot do

• How to Persist Your FHIR Data

• Serializing Your FHIR Data

• Working with a FHIR Server

Origin Story

Or How I Accidentally Find Myself in Amsterdam

What Is FireKit?

• A FHIR DSTU2 implementation in Swift• Full CRUD support with Realm

• Full Serialization to/from JSON• Swift 4 Codable compliant

• NSCopying compliant

• Realm CRUD helper functions

• Distributed under Apache 2 license

FireKit Limitations

• No API client… yet• BYOC: Bring Your Own Client

• More on this later

• Beholden to Realm’s “Rules of Engagement”• No implicit sharing of FHIR resources across thread

boundaries

• Writes must occur in a transaction

• No List of primitives

Creating a FHIR Resource

• Import FireKit; Import RealmSwift• FireKit contains the FHIR DSTU2

schema

• RealmSwift is the Realm Swift API



schema


• Create a new Patient



schema



• Give that Patient a name!



schema



• Give that Patient a name!

• Finally, save that patient• FireKit provides the primary key

• String property called pk

Retrieving Realm Objects

• Realm provides query mechanics• objects<T>(_: T.Type) -> Results<T>

• filter

• Sorted

• object<T>(_: T.Type, forPrimaryKey) -> T?

• FireKit provides 2 extensions:• resources<T>(_: T.Type, withIds: [String]) -> Results<T>

• resource<T>(_: T.Type, withId: String) -> T?

Retrieving All Objects for a Type

• Use objects(_:) to retrieve a Results list of those objects

Retrieving All Objects for a Type


Filter Results


• Use filter(_:) to filter the results.

Sort Results


• Use filter(_:) to filter the results.

• Use sorted(_:) to sort the results by field

See more filter options at https://academy.realm.io/posts/nspredicate-cheatsheet/

https://academy.realm.io/posts/nspredicate-cheatsheet/

Get an Object by Primary Key

• object(ofType:, forPrimaryKey)• Returns the object, or nil

• Remember: Every FireKit object has a primary key

FireKit Extension: Getting Resources

• Query for type where id is in list

• This is a convenience function • Wraps around realm.objects and

filter

FireKit Extension: Getting Resources

• Query for type where id is in list

• This is a convenience function • Wraps around realm.objects and

filter

• Can also apply filter and sorted

FireKit Extension: Get Single Resource by id

• Get a single resource of a given type by it’s resource id

Managed vs. Unmanaged Realm Objects

• Unmanaged Objects are not in a Realm• New, unsaved objects


• An object becomes managed when it’s persisted to a realm



• Once managed, the object cannotbe modified outside a write transaction.



• Once managed, the object cannotbe modified outside a write transaction.• Wrap the edit in a write block

• Alternatively, use beginWrite() and commitWrite()

Editing a Resource

• 4 ways to edit a FHIR Resource• Edit individual properties

• upsert a property

• Use copy/populate technique

• Bonus Jonus! realm.upsert<T>(:)

• All must be performed inside a write transaction

Editing a Resource – Individual Properties

• We’ve already seen this• Update individual properties in write

transaction

Editing a Resource – Individual Properties

• We’ve already seen this• Update individual properties in write

transaction

Editing a Resource – Upserting a property

• upsert(:)• To update or insert

• Create a template of what you want

• Blindly assign template property• Spouses will not share status

Editing a Resource – Copy/Populate

• copy()• provides unmanaged copy of the

source

• Does not duplicate primary keys

• populate(from:)• migrates values from source to

target

• Complete replacement; • does not perform intelligent merge

Editing a Resource – Bonus Jonus!

• What to do with downloaded Resources?• Update? Create a new one?

• Neither! You upsert it!• Logic based on the Resource’s id

• Will insert or update appropriately

Editing a Resource – Bonus Jonus!

• What to do with remote Resources?• Update? Create a new one?

• Neither! You upsert it!• Logic based on the Resource’s id

• Will insert or update appropriately

• Also handles arrays of Resources

Deleting a Resource

• Don’t use Realm’s realm.delete(:) on Resources or Elements• Does not cascade

• Risks orphans

• Use FireKit’s cascadeDelete()• Properly deletes

Resources/Elements

• No more orphans

JSON Serialization

• All FireKit classes conform to Swift 4’s Codable protocol

JSON Serialization

• All FireKit classes conform to Swift 4’s Codable protocol• Serialize using Swift 4’s JSONEncoder

JSON Serialization

• All FireKit classes conform to Swift 4’s Codable protocol• Serialize using Swift 4’s JSONEncoder

• Deserialize using Swift 4’s JSONDecoder

Integrating with a FHIR Server

• No API client in FireKit• Yet?

• Use Restivus as a simple alternativehttps://ryanbaldwin.github.io/Restivus

• Protocol-oriented

• Works around Swift 4’s Encodableand Decodable protocols

• Focus on structure, not on infrastructure

https://ryanbaldwin.github.io/Restivus

An Example Restivus Request

• Get the contents of the Google Home Page• Model the request



• Conform it to the proper Protocol• Gettable

• Postable

• Puttable

• Patchable

• Deletable




• Postable

• Puttable

• Patchable

• Deletable

• What are we expecting back? Where are we fetching from?




• Postable

• Puttable

• Patchable

• Deletable

• What are we expecting back? Where are we fetching from?

• Submit it!

Another Example – Download a Patient

• Create the request



• Conform the request to Gettable• We are expecting a Patient

• Use String interpolation to construct the path dynamically



• Conform the request to Gettable• We are expecting a Patient

• Use String interpolation to construct the path dynamically

• Submit it!

Last Example – Post a Patient




• Conform to Postable• Expect an OperationOutcome




• Conform to Encodable• Populates the request body with

JSON

• Single Value Container for just the Patient JSON




• Conform to Encodable• Populates the request body with

JSON

• Single Value Container for just the Patient JSON

• Submit it!

FireKit + Restivus = Easy Basic Client

• FireKit Codables

• Much more to Restivus than presented• Should be enough to get you started

Summary

• FireKit• Provides a Realm-ready FHIR DSTU2 spec

• Easily update and delete complex FHIR models in Realm

• Codable Conformant – Easily Serialize/Deserialze your data

• NSCopying Conformant – Easily copy your data

• Restivus• Easily create and submit Requests to a Server

• Automatically inflates ready-to-use responses from JSON

• Stays out of your way

That’s all she wrote!

FireKit:https://github.com/ryanbaldwin/FireKit

Restivus:https://ryanbaldwin.github.io/Restivus

Codable:http://apple.co/2AqcloLhttp://bit.ly/2znNuSn http://bit.ly/2yes7kU

https://github.com/ryanbaldwin/FireKit

https://ryanbaldwin.github.io/Restivus

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