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

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FHIR® is the registered trademark of HL7 and is used with the permission of HL7. The Flame Design mark is the registered trademark of HL7 and is used with the permission of HL7.

Amsterdam, 15-17 November | @fhir_furore | #fhirdevdays17 | www.fhirdevdays.com

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/

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

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

• Single Value Container for just the Patient JSON

• Conform to Encodable• Populates the request body with

• 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

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

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