Batch/Transaction

Do multiple operations in one call

Introduction

Transaction interaction allows performing several interactions using one http request. There are two types of transaction interaction (type is specified by field type): batch and transaction. The first one just executes requests one by one, the second one does the same, but roll backs all changes if any request fails.

POST [base]

The body of such request contains one resource of type Bundle, which contains field entry with an array of interactions, for example: \

POST /
​Accept: text/yaml
Content-Type: text/yaml

type: transaction
entry:
- resource:
    id: admin
    email: "admin@mail.com" # Change this value
    password: "password" # Change this value
  request:
    method: POST
    url: "/User"
​
- resource:
    id: SPA
    redirect_uri: http://localhost:4200
  request:
    method: POST
    url: "/Client"
    
- resource:
    engine: json-schema
    schema:
      type: object
      required:
      - user
  request:
    method: POST
    url: "/AccessPolicy"

Each element of the entry array contains a resource field (body of the request) and a request field (request line in terms of the HTTP request).

resource: # not needed for DELETE and GET
  # resource here

fullUrl: "something-here" # needed if you want to refer
                          # the resource inside bundle
request:
  method: POST # POST/GET/PUT/DELETE
  url: "/ResourceType" # request url

Processing rules and Conditional refs

Transaction interaction is processed in the order provided in a bundle, each interaction is executed one by one. It differs from the FHIR transaction processing rules.

For type: batch references to resources inside a bundle won't be resolved.

For type: transaction before processing interactions, all references in a resource will attempt to resolve. In this example ProcedureRequest will refer to a newly created patient:

POST /
Accept: text/yaml
Content-Type: text/yaml

type: transaction
entry:
- resource:
    resourceType: Patient
  fullUrl: urn:uuid:<uuid-here>
  request:
    method: POST
    url: "/Patient?_identifier=mrn:123"
    
- resource:
    resourceType: Encounter
    status: proposal
    subject:
      uri: urn:uuid:<uuid-here>
  request:
    method: POST
    url: "/Encounter"

You can provide a full Url with value like "urn:<uuid-here>" and reference to the resource created by such interaction using ref: {uri: "urn:<uuid-here>"}. Those references are temporary and will be translated to valid Aidbox references when interaction entry is processed by a server.

You SHALL NOT refer resource, which is created later using conditional operations!

Multiple resources with the same id

If you have multiple entries with the same resource id, aidbox will execute them one by one and thus you are able to create a resource with a history in within a single transaction:

POST /
Accept: text/yaml
Content-Type: text/yaml

resourceType: Bundle
type: transaction
entry:
- request: {method: PUT, url: 'Patient/pt-1'}
  resource: {birthDate: '2021-01-01'}
- request: {method: PUT, url: 'Patient/pt-1'}
  resource: {birthDate: '2021-01-02'}
- request: {method: PUT, url: 'Patient/pt-1'}
  resource: {birthDate: '2021-01-03'}
GET /Patient/pt-1
Accept: text/yaml
GET /Patient/pt-1/_history
Accept: text/yaml
Content-Type: text/yaml

resourceType: Bundle
type: history
total: 3
entry:
- resource: {birthDate: '2021-01-03', id: pt-1, resourceType: Patient}
- resource: {birthDate: '2021-01-02', id: pt-1, resourceType: Patient}
- resource: {birthDate: '2021-01-01', id: pt-1, resourceType: Patient}

Change transaction isolation level

By default Aidbox uses SERIALIZABLE transaction isolation level. This may lead to some transactions being rejected when there are many concurrent requests.

See more about transaction isolation in Postgres documentation.

The best way to handle rejected transactions is to retry them. If it is not possible, you can set maximum isolation level with HTTP header or environment variable. If both HTTP header and environment variable are provided, header will be used.

Using isolation level lower than serializable may lead to data serialization anomalies.

Example:

POST /fhir
x-max-isolation-level: read-committed
content-type: text/yaml
accept: text/yaml

resourceType: Bundle
type: transaction
entry:
  - request:
      method: PUT
      url: "/Patient/pt-1"
    resource:
      active: true
  - request:
      method: PUT
      url: "/Patient/pt-2"
    resource:
      active: false

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