7.7. Patching Resources

OpenDJ lets you patch JSON resources, updating part of the resource rather than replacing it. For example, you could change Babs Jensen's email address by issuing an HTTP PATCH request, as in the example that follows.

Notice that the data sent specifies the type of patch operation, the field to change, and a value that depends on the field you change and on the operation. A single-valued field takes an object, boolean, string, or number depending on its type, whereas a multi-valued field takes an array of values. Getting the type wrong results in an error. Also notice that the patch data is itself an array, since you could patch more than one part of the resource by using a set of patch operations in the same request. 

$ curl
 --user kvaughan:bribery
 --request PATCH
 --header "Content-Type: application/json"
 --data '[
  {
    "operation": "replace",
    "field": "/contactInformation/emailAddress",
    "value": "babs@example.com"
  }
 ]'
 http://opendj.example.com:8080/users/bjensen?_prettyPrint=true
{
  "_rev" : "00000000f3fdd370",
  "schemas" : [ "urn:scim:schemas:core:1.0" ],
  "contactInformation" : {
    "telephoneNumber" : "+1 408 555 1862",
    "emailAddress" : "babs@example.com"
  },
  "_id" : "bjensen",
  "name" : {
    "familyName" : "Jensen",
    "givenName" : "Barbara"
  },
  "userName" : "babs@example.com",
  "displayName" : "Barbara Jensen",
  "meta" : {
    "lastModified" : "2013-05-13T14:35:31Z"
  },
  "manager" : [ {
    "_id" : "trigden",
    "displayName" : "Torrey Rigden"
  } ]
}

OpenDJ supports four types of patch operation.

"add"

The add operation ensures that the target field contains the value provided, creating parent fields as necessary.

If the target field is single-valued and a value already exists, then that value is replaced with the value you provide. Note that you do not get an error when adding a value to a single-valued field that already has a value. A single-valued field is one whose value is not an array (an object, string, boolean, or number).

If the target field is multi-valued, then the array of values you provide is merged with the set of values already in the resource. New values are added, and duplicate values are ignored. A multi-valued field takes an array value.

"remove"

The remove operation ensures that the target field does not contain the value provided. If you do not provide a value, the entire field is removed if it already exists.

If the target field is single-valued and a value is provided, then the provided value must match the existing value to remove, otherwise the field is left unchanged.

If the target field is multi-valued, then values in the array you provide are removed from the existing set of values.

"replace"

The replace operation removes existing values on the target field, and replaces them with the values you provide. It is equivalent to performing a remove on the field, then an add with the values you provide.

"increment"

The increment operation increments or decrements the value or values in the target field by the amount you specify, which is positive to increment, negative to decrement. The target field must be a number or a set of numbers. The value you provide must be a single number.

One key nuance in how patch works with OpenDJ has to do with multi-valued fields. Although JSON resources represent multi-valued fields as arrays, OpenDJ treats those values as sets. In other words, values in the field are unique, and the ordering of an array of values is not meaningful in the context of patch operations. If you reference array values by index, OpenDJ returns an error.[5]

Instead use the patch operations as if arrays values were sets. For example, you can include Barbara Jensen in a group by adding her to the set of members. 

$ curl
 --user kvaughan:bribery
 --request PATCH
 --header "Content-Type: application/json"
 --data '[
  {
    "operation": "add",
    "field": "/members",
    "value": [
      {
        "_id": "bjensen"
      }
    ]
  }
 ]'
 http://opendj.example.com:8080/groups/Directory%20Administrators
 ?_prettyPrint=true
{
  "_rev" : "00000000b70c881a",
  "schemas" : [ "urn:scim:schemas:core:1.0" ],
  "_id" : "Directory Administrators",
  "displayName" : "Directory Administrators",
  "meta" : {
    "lastModified" : "2013-05-13T16:40:23Z"
  },
  "members" : [ {
    "_id" : "kvaughan",
    "displayName" : "Kirsten Vaughan"
  }, {
    "_id" : "rdaugherty",
    "displayName" : "Robert Daugherty"
  }, {
    "_id" : "bjensen",
    "displayName" : "Barbara Jensen"
  }, {
    "_id" : "hmiller",
    "displayName" : "Harry Miller"
  } ]
}

Removing her from the group is similar.

$ curl
 --user kvaughan:bribery
 --request PATCH
 --header "Content-Type: application/json"
 --data '[
  {
    "operation": "remove",
    "field": "/members",
    "value": [
      {
        "_id": "bjensen"
      }
    ]
  }
 ]'
 http://opendj.example.com:8080/groups/Directory%20Administrators
 ?_prettyPrint=true
{
  "_rev" : "00000000e241797e",
  "schemas" : [ "urn:scim:schemas:core:1.0" ],
  "_id" : "Directory Administrators",
  "displayName" : "Directory Administrators",
  "meta" : {
    "lastModified" : "2013-05-13T16:40:55Z"
  },
  "members" : [ {
    "_id" : "kvaughan",
    "displayName" : "Kirsten Vaughan"
  }, {
    "_id" : "rdaugherty",
    "displayName" : "Robert Daugherty"
  }, {
    "_id" : "hmiller",
    "displayName" : "Harry Miller"
  } ]
}

You can use resource revision numbers in If-Match: revision headers to patch the resource only if the resource matches a particular version. 

$ curl
 --user kvaughan:bribery
 "http://opendj.example.com:8080/users/bjensen?_prettyPrint=true&_fields=_rev"
{
  "_rev" : "00000000c1b6d4c7"
}
$ curl
 --user kvaughan:bribery
 --request PATCH
 --header "If-Match: 00000000c1b6d4c7"
 --header "Content-Type: application/json"
 --data '[
  {
    "operation": "add",
    "field": "/contactInformation/emailAddress",
    "value": "babs@example.com"
  }
 ]'
 http://opendj.example.com:8080/users/bjensen?_prettyPrint=true
{
  "_rev" : "00000000f946d377",
  "schemas" : [ "urn:scim:schemas:core:1.0" ],
  "contactInformation" : {
    "telephoneNumber" : "+1 408 555 1862",
    "emailAddress" : "babs@example.com"
  },
  "_id" : "bjensen",
  "name" : {
    "familyName" : "Jensen",
    "givenName" : "Barbara"
  },
  "userName" : "babs@example.com",
  "displayName" : "Barbara Jensen",
  "meta" : {
    "lastModified" : "2013-05-13T16:56:33Z"
  },
  "manager" : [ {
    "_id" : "trigden",
    "displayName" : "Torrey Rigden"
  } ]
}

The resource revision changes after you successfully perform the patch operation.


[5] OpenDJ does let you use a hyphen as the last element of the "field" JSON pointer value to add an element to the set, as in curl --user kvaughan:bribery --request PATCH --header "Content-Type: application/json" --data '[{ "operation" : "add", "field" : "/members/-", "value" : { "_id" : "bjensen" } }]' http://opendj.example.com:8080/groups/Directory%20Administrators.