fhir search for client developers by mirjam baltus

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FHIR Searchfor client developers

Mirjam Baltus

FHIR Developer Days

November 24, 2014


Who am I?

Name: Mirjam Baltus-Bakker

Company: Furore, Amsterdam

Background:

ICT trainer

Furore FHIR team

Contact:

[email protected]

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mailto:[email protected]


Searching FHIR

Understanding search

Basic search

Search parameters

Parameter types

More complex searches

Search using the API


Basic search

Syntax

GET [base-url]/[resourcetype](?parameters)

Getting all patients

GET http://acme.org/fhir/Patient

Always returns a paged feed

Use _count for number of results per page

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Basic search

Special case of the “real” search operation:

http://acme.org/fhir/Patient?_id=23

http://acme.org/fhir/Patient/23

http://acme.org/fhir/Patient?name=eve

OperationOutcome resource

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Searching FHIR


Basic search

Search parameters

Parameter types




Search (patient)

Each resource has a set of “standard” search parameters,

so not every element can be searched!:

Our last search

used this one

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Conformance

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Searching FHIR


Basic search

Search parameters

Parameter types




Search (patient)

Each search parameter has a ‘type’

Parameter

Type

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Parameter types

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number: =, =<, =<=, =>, =>=

Significant digits matter

date: =, =<, =<=, =>, =>=

Matches calculated using interval operations

Precision turns all dates into intervals

string: =

“contains” search, ignoring case, accents

Can use :exact to be case and accent-sensitive

Search for [param]=2013-01-14 returns

resources where [param] is between

2013-01-14T00:00 and 2013-01-14T23:59

Search for [param]=>2013-01-14T10:00

includes resources where [param] has

a value of 2013-01-14

http://acme.org/fhir/Patient?name:exact=Eve


Parameter types (cont’d)

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token: =

[code] matches codes/identifier values

independent of system

[system]|[code/value] matches a specified code or

identifier within the specified system

|[code/value] matches the specified code or

identifier in instances where no system is declared

:text performs a string search on

CodeableConcept.text, Coding.display and

Identifier.label

http://acme.org/fhir/Patient?gender=M

http://acme.org/fhir/Patient?

gender=v3/AdministrativeGender|M


Parameter types (cont’d)

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quantity: =, =<, =>, =<=, =>=

[comparator][number]|[system]|[code]

Follows rules for number + token together for

value + units of quantity

reference: =

Either the local or absolute id

:type filters resource type

http://acme.org/fhir/Observation?

value=5.4|http://unitsofmeasure.org|mg

http://acme.org/fhir/DiagnosticReport?

subject=Patient/23


Ok I get it…or not?

http://acme.org/fhir/Patient/ 406 hits

http://acme.org/fhir/Patient?gender=M 234 hits

http://acme.org/fhir/Patient?gender=F 167 hits

Total: 234 + 167 = 401

http://acme.org/fhir/Patient/ 406 hits

http://acme.org/fhir/Patient?gender=M 234 hits

http://acme.org/fhir/Patient?gender=F 167 hits

http://acme.org/fhir/Patient?gender:missing=true 5 hits

Total: 234 + 167 + 5 = 406

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Searching FHIR


Basic search

Search parameters

Parameter types




Combining parameters

Specifying multiple parameters finds

resources matching all params “AND”

Parameters may list multiple values “OR”

Try:

http://acme.org/fhir/Patient?

birthdate=1972-11-30&language=nl,fr

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Chained searches

Patient has a search for “name”.

Observation has a search for “subject” (the

id of the Patient, Group or Device)

How do I find Observations for a patient,

searching using his name?

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2 queries in 1

You (as a client) don’t need to do separate

operations, just one:

http://acme.org/fhir/Observation?

But note: this still only works on the predefined

search parameters. You cannot just use any

property of the resource.

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subject:Patient.name=jimsubject.name=jim


More optimalizations

Say we do:http://acme.org/fhir/DiagnosticReport?

date=2013-03-11

We get back: a Bundle with 0..* “DiagnosticReports”

Now, usually, wouldn’t we want the Patient

information too? => Need to do “N” queries

for the DiagnosticReport’s “subject”

Quicker: _include=DiagnosticReport.subject

Returns both DiagnosticReports + Patients19


Summary

Some resources can be “big”

e.g. Patient with pictures & lots of contacts

10MB JSON result set is bad when you’re an

Android app presenting a list of 100 patients for a

clinician to scroll through

Solution: _summary=true strips a

resource’s elements down to those most

likely to be useful in a “list” view.

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Sorting

Use _sort:asc or _sort:desc to control sort

E.g. Observation?_sort:asc=name&_sort:desc

=date

Sorts observations of the same type together,

newest first

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Searching FHIR


Basic search

Search parameters

Parameter types





Demo in .Net


Final words

FHIR has a lot of query capability

However . . .

Almost all of it is optional

So how do you design a client when you have no

clue what the server will support?

The more generic you want your client to be, the less

you should rely on sophisticated server capabilities

Always check the response to see what parameters

were actually used26


Questions?

http://hl7.org/fhir [email protected]

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http://hl7.org/fhir

mailto:[email protected]

fhir search for client developers by mirjam baltus

Healthcare

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hl7 international

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real search operation

patientsget http

parameter types11number

basic searchspecial