Objects: compose
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Concatenates a list of existing objects into a new object in the same bucket. The existing source objects are unaffected by this operation.

See Composite objects for a general discussion of object composition, and see Compose objects for tool-specific guides to performing a composition.

Required permissions

The authenticated user must have the storage.objects.create and storage.objects.get IAM permissions to use this method. If the new composite object overwrites an existing object, the authenticated user must also have the storage.objects.delete permission. If the request body includes the retention property, the authenticated user must also have the storage.objects.setRetention IAM permission.

Request

HTTP request

POST https://storage.googleapis.com/storage/v1/b/bucket/o/destinationObject/compose

In addition to standard query parameters, the following query parameters apply to this method.

To see an example of how to include query parameters in a request, see the JSON API Overview page.

Parameters

Parameter name	Value	Description
Path parameters
`bucket`	`string`	Name of the bucket containing the source objects. The destination object is stored in this bucket.
`destinationObject`	`string`	Name of the new object. For information about how to URL encode object names to be path safe, see Encoding URI path parts.
Optional query parameters
`destinationPredefinedAcl`	`string`	Apply a predefined set of access controls to the destination object. Acceptable values are: `authenticatedRead`: Object owner gets `OWNER` access, and `allAuthenticatedUsers` get `READER` access. `bucketOwnerFullControl`: Object owner gets `OWNER` access, and project team owners get `OWNER` access. `bucketOwnerRead`: Object owner gets `OWNER` access, and project team owners get `READER` access. `private`: Object owner gets `OWNER` access. `projectPrivate`: Object owner gets `OWNER` access, and project team members get access according to their roles. `publicRead`: Object owner gets `OWNER` access, and `allUsers` get `READER` access. If `iamConfiguration.uniformBucketLevelAccess.enabled` is set to `true`, requests that include this parameter fail with a `400 Bad Request` response.
`ifGenerationMatch`	`long`	Makes the operation conditional on there being a live destination object with a generation number that matches the given value. Setting `ifGenerationMatch` to 0 makes the operation succeed only if there is no live destination object.
`ifMetagenerationMatch`	`long`	Makes the operation conditional on there being a live destination object with a metageneration number that matches the given value.
`kmsKeyName`	`string`	Resource name of the Cloud KMS key that will be used to encrypt the composed object. If not specified, the request uses the bucket's default Cloud KMS key, if any, or else it uses standard Cloud Storage encryption.
Optional extension headers
`X-Goog-Encryption-Algorithm`	`string`	The encryption algorithm to use, which must be `AES256`. Used when encrypting the composed object with a customer-supplied encryption key.
`X-Goog-Encryption-Key`	`string`	An RFC 4648 Base64-encoded string of your AES-256 encryption key. Used when encrypting the composed object with a customer-supplied encryption key.
`X-Goog-Encryption-Key-Sha256`	`string`	An RFC 4648 Base64-encoded string of the SHA256 hash of your encryption key. Used when encrypting the composed object with a customer-supplied encryption key.

Request body

In the request body, supply data with the following structure:

{
  "kind": "storage#composeRequest",
  "sourceObjects": [
    {
      "name": string,
      "generation": "long",
      "objectPreconditions": {
        "ifGenerationMatch": "long"
      }
    }
  ],
  "destination": objects Resource
}

Property name	Value	Description	Notes
`kind`	`string`	The kind of item this is.
`destination`	`nested object`	Properties of the resulting object.	writable
`sourceObjects[]`	`list`	The list of source objects that will be concatenated into a single object. There is a limit of 32 components that can be composed in a single operation.
`sourceObjects[].name`	`string`	The source object's name. All source objects must reside in the same bucket and use the same storage class.	writable
`sourceObjects[].generation`	`long`¹	The generation of this object to use as the source.	writable
`sourceObjects[].objectPreconditions`	`object`	Conditions that must be met for this operation to execute.
`sourceObjects[].objectPreconditions.ifGenerationMatch`	`long`¹	Only perform the composition if the generation of the source object that would be used matches this value. If this value and a generation are both specified, they must be the same value or the call will fail.	writable

¹ This property is a string formatted as the specified value type.

Response

If successful, this method returns an object resource in the response body, with the owner and acl properties omitted.

For information about status and error codes returned by this API, see the reference page.

Try it!

Use the APIs Explorer below to call this method on live data and see the response.

Objects: composeStay organized with collections Save and categorize content based on your preferences.