Constructing composite requests

The `/composite` endpoint

To create a composite request, use the /composite endpoint in the Composite API. This is different than batches. Every API has its own /batch endpoint. But in all of Cloud API, there is only one /composite endpoint, and it is in the Composite API.

The syntax for the composite request call is:

POST <applicationURL>/rest/composite/v1/composite

Sections of a composite request

A composite request can have up to two sections:

A requests section, which contains the subrequests that commit data.
A selections section, which contains the subselections that query for data. These are executed after the subrequests, and only if all the subrequests commit data successfully.

At a high level, the syntax for these sections is as follows:

{
  "requests": [
    {
      <subrequest 1>
    },
    {
      <subrequest 2>
    },
    ...
  ],
  "selections": [
    {
      <subselection 1>
    },
    {
      <subselection 2>
    },
    ...
  ]
}

The `requests` section

In the requests section, the only supported operations are POST, PATCH, and DELETE. This includes both POSTs that create data and POSTs that execute business actions (such as POST /assign).

The basic syntax for the requests section is shown below.

{
  "requests": [
    {
      "method": "<post/patch/delete>",
      "uri": "<path>",
      "body": {
        "data": {
          "attributes": {
            "<field1>": "<value1>",
            "<field2>": "<value2>",
            ...
            }
        }
      }
    }, 
    {
      <next subrequest>
    },
    ...
    {
      <final subrequest>
    }
  ]
}

For example, the following simple composite request creates two notes for activity xc:202.

POST <applicationURL>/rest/composite/v1/composite

{
  "requests": [   
    {
      "method": "post",
      "uri": "/common/v1/activities/xc:202/notes",
      "body": {
        "data": {
          "attributes": {
            "body": "Cloud API note #1."
          }
        }
      }
    },    
    {
      "method": "post",
      "uri": "/common/v1/activities/xc:202/notes",
      "body": {
        "data": {
          "attributes": {
            "body": "Cloud API note #2."
          }
        }
      }
    }
  ]
}

For the complete syntax that includes all composite request features, see Complete composite request syntax.

Using variables to share information across subrequests

Information from one subrequest can be used in later subrequests. You can do this through the use of composite variables.

Declaring variables

Composite variables are declared in a subrequest's vars section. Each variable has a name and path. The name is an arbitrary string. The path specifies what to set the variable to. It is set to a JSON path expression that identifies a value in the subrequest's response payload.

For example, suppose a subrequest that creates an activity has the following:

      "vars": [
        {
          "name": "newActivityId",
          "path": "$.data.attributes.id"
        }
      ]

This creates a variable named newActivityId, which is set to the value of the data section's attributes section's id field (which would typically be the id of the newly created activity).

Referencing variables

To reference a variable, use the following syntax:

${<varName>}

You can use variables anywhere in the body of a subrequest. The most common uses for variable values are:

In an attributes field
Within the path of a uri
As part of a query parameter

For example, suppose there is a subrequest that creates an activity, and it is followed by a subrequest that creates a note. The first subrequest creates a newActivityId variable as shown previously. The uri for the second subrequest is:

"uri": "/common/v1/activities/${newActivityId}/notes"

This would create the new note as a child of the first subrequest's activity.

The following is the complete code for the previous examples.

{
  "requests": [
    {
      "method": "post",
      "uri": "/claim/v1/claims/cc:34/activities",
      "body": {
        "data": {
          "attributes": {
              "activityPattern": "contact_insured",
              "subject": "Cloud API activity"
          }
        }
      },
      "vars": [
        {
          "name": "newActivityId",
          "path": "$.data.attributes.id"
        }
      ]
    },    
    {
      "method": "post",
      "uri": "/common/v1/activities/${newActivityId}/notes",
      "body": {
        "data": {
          "attributes": {
            "body": "Cloud API note #1."
          }
        }
      }
    }
  ]
}

Responses to the subrequests

The response to a composite request contains a responses section. This section contains one subresponse for each subrequest. Every subresponse has three sections:

A body section, which by default contains the default response data defined in the corresponding endpoint.
A headers section, which contains any custom headers.
A status field, which indicates the subresponse's status code.

For example, the following is the responses section and the first subresponse for a composite request whose first subrequest created an activity:

"responses": [
  {
    "body": {
      "data": {
        "attributes": {
          "activityPattern": "contact_insured",
          "activityType": {
            "code": "general",
            "name": "General"
            },
          "assignedByUser": {
            "displayName": "Andy Applegate",
            "id": "demo_sample:1",
            "type": "User",
            "uri": "/admin/v1/users/demo_sample:1"
          },
          ...
        },
        "checksum": "0",
        "links": {
          "assign": {
            "href": "/common/v1/activities/cc:403/assign",
            "methods": [
              "post"
            ]
          },
          ...
        }
      }
    },
    "headers": {
      "GW-Checksum": "0",
      "Location": "/common/v1/activities/xc:403"
    },
    "status": 201
  },

Fields whose values are generated when data is committed

The individual subresponses to each subrequest specify data that has technically not been committed yet. However, some fields contain values that are not generated until the data is committed.

When a subresponse includes a value that is generated as part of the commit, Cloud API makes effort to match the data that will be committed as closely as possible. For example, the composite request reserves ID values so that these IDs can be provided in subresponses and committed to the database.

But, there are some fields for which Cloud API cannot match the value. For example, when executing a POST, the values for createTime and updateTime cannot be determined prior to the commit. Fields of this type are always omitted from a subrequest's subresponse. But, they can be retrieved through a subselection.

Subresponse values can be out of date

As noted above, the individual subresponses to each subrequest specify data that has technically not been committed yet. This means it is possible for some fields in a subresponse to be out of date by the time the entire composite request has been processed.

For example, suppose you have a composite request that includes several subrequests. The first subrequest POSTs an activity, and the subresponse for this subrequest includes a checksum value. When the composite request is actually committed to the database, the actual checksum value may differ from the one initially provided in the subresponse.

If a composite request is followed by a related request and the related request must have the most up-to-date values, then the composite request must contain a selections section that retrieves the required values. The GETs in the selections section are always executed after all subrequests have been committed.

Suppressing subresponse details

In some cases, a given object may be modified by multiple subrequests. This makes the intermediate subresponses unnecessary, and those subresponses can increase the size of the composite response unnecessarily and make the composite response harder to parse.

You can simplify the composite response by suppressing the amount of information returned for one or more subrequests. To do this, include the following with each relevant subrequest:

"includeResponse": false

For example:

{
  "requests": [   
    {
      "method": "post",
      "uri": "/common/v1/activities/xc:202/notes",
      "body": {
        "data": {
          "attributes": {
            "body": "Cloud API note #1."
          }
        }
      },
      "includeResponse": false
    },
    ...

The composite response still includes a subresponse for the subrequest. But instead of providing the endpoint's default response, the subresponse appears as:

{
    "responseIncluded": false
},

The responseIncluded field defaults to true. If you want a detailed response for a given subrequest, simply omit the responseIncluded reference.

Using query parameters in subrequests

For a POST or PATCH subrequest, you can also refine which fields are returned. To do this, use the fields query parameter. The syntax for this is:

{
  "requests": [
    {
      "method": "<post/patch>",
      "uri": "<path>",
      "body": {
        "data": {
          "attributes": {
            "<field1>": "<value1>",
            "<field2>": "<value2>",
            ...
            }
        }
      },
      "parameters" : {
        "fields" : "<value>"
      }
    }, 
    ...
  ]
}

For example, the following code snippet creates an activity. For the subresponse, it specifies to include only the activity's id and the assigned user.

{
  "requests": [
    {
      "method": "post",
      "uri": "/claim/v1/claims/cc:34/activities",
      "body": {
        "data": {
          "attributes": {
              "activityPattern": "contact_insured",
              "subject": "Cloud API activity"
          }
        }
      },
      "parameters" : {
        "fields" : "id,assignedUser"
      }
    },
  ...

For a given API, you can see a complete list of all query parameters that can be used in composite requests by executing a GET /openapi.json call. If a query parameter is available to composite requests, the OpenAPI output will include the following line: "x-gw-allowForCompositeApi": true.

The `selections` section

The selections section contains subselections that query for data. These are executed after the subselections in the requests section (if any), and only if all the subrequests commit data successfully.

The basic syntax for the selections section is shown below. You do not need to specify a method for each subselection, as the only valid method in the selections section is GET.

  "selections": [
    {
      "uri": "<pathForFirstSubselection>"
    },
    {
      "uri": "<pathForSecondSubselection>"
    },
    ....
  ]

For example, the following code creates a new activity and a note for that activity. It then queries for the newly created activity.

{
  "requests": [
    {
      "method": "post",
      "uri": "/claim/v1/claims/cc:34/activities",
      "body": {
        "data": {
          "attributes": {
              "activityPattern": "contact_insured",
              "subject": "Cloud API activity"
          }
        }
      },
      "vars": [
        {
          "name": "newActivityId",
          "path": "$.data.attributes.id"
        }
      ]
    },    
    {
      "method": "post",
      "uri": "/common/v1/activities/${newActivityId}/notes",
      "body": {
        "data": {
          "attributes": {
            "body": "Cloud API note #1."
          }
        }
      }
    }
  ],
  "selections": [
    {
      "uri": "/common/v1/activities/${newActivityId}"
    }
  ]
}

For the complete syntax that includes all composite request features, see Complete composite request syntax.

Using query parameters in the selections section

You can use certain query parameters for each subselection. This includes:

fields
filter
includeTotal
pageOffset
pageSize
sort

Each subselection is independent from the others. You can use different query parameters for each subselection, and you can have some subselections with query parameters and others without query parameters.

The syntax for adding query parameters to a subselection is as follows:

  "selections": [
    {
      "uri": "<pathForFirstQuery>",
      "parameters" : {
        "fields" : "<value>",
        "filter" : [<value>],
        "includeTotal" : <value>,
        "pageOffset" : <value>,
        "pageSize" : <value>,
        "sort" : [<value>]
      }
    },
    ....
  ]

Note the following:

fields is specified as a single string of one or more fields, delimited by commas. The entire string is surrounded by quotes.
- For example, "assignedUser,dueDate,priority,subject"
filter and sort are stringified arrays consisting of one or more expressions. Each individual expression is surrounded by quotes. The list of expressions is then surrounded by [ and ].
- For example: ["dueDate:gt:2022-12-20","status:in:open,complete"]
includeTotal , pageOffset, and pageSize are either Boolean or integer values, and therefore do not use quotes.

For example, when querying for activities, to return only the assigned user, due date, priority and subject fields:

    {
      "uri": "/common/v1/activities",
      "parameters" : {
        "fields" : "assignedUser,dueDate,priority,subject"
      }

To return only open and complete activities with due dates after 2022-12-20:

    {
      "uri": "/common/v1/activities",
      "parameters" : {
        "filter" : ["dueDate:gt:2022-12-20","status:in:open,complete"]      }

To return activities based on multiple criteria:

    {
      "uri": "/common/v1/activities",
      "parameters" : {
        "fields" : "assignedUser,dueDate,priority,subject",
        "filter" : ["dueDate:gt:2022-12-20","status:in:open,complete"],
        "includeTotal" : true,
        "pageSize" : 5,
        "sort" : ["dueDate"]
      }

There may be additional query parameters you can use. For information on how to determine whether a query parameter is supported in a composite request, see Composite request limitations.

Composite requests that execute only queries

You can create a composite request that does not create or modify data and instead only queries for data. To do this, create a composite request with only a selections section and no requests section. In this case, the GETs in the selections section are always executed.

Responses to the selections subrequests

When a composite request contains a selections section, the response also contains a selections section. This section has the same structure as the responses section. It contains one subresponse for each subselection. Every subresponse has three sections:

A body section, which by default contains the default response data defined in the corresponding endpoint.
A headers section, which contains any custom headers.
A status field, which indicates the subresponse's status code.

Composite request examples

This documentation includes examples of composite requests for common business tasks. This includes the following:

Creating a new claim with an unverified policy: Sample composite claim payload
Creating, closing, and paying out a claim: Sample composite first-and-final