Uploads

Generates batches of presigned URLs for multipart parts

POST

https://discourse.example.com/uploads/batch-presign-multipart-parts.json

Multipart uploads are uploaded in chunks or parts to individual presigned URLs, similar to the one generated by /generate-presigned-put. The part numbers provided must be between 1 and 10000. The total number of parts will depend on the chunk size in bytes that you intend to use to upload each chunk. For example a 12MB file may have 2 5MB chunks and a final 2MB chunk, for part numbers 1, 2, and 3.

This endpoint will return a presigned URL for each part number provided, which you can then use to send PUT requests for the binary chunk corresponding to that part. When the part is uploaded, the provider should return an ETag for the part, and this should be stored along with the part number, because this is needed to complete the multipart upload.

You must have the correct permissions and CORS settings configured in your external provider. We support AWS S3 as the default. See:

https://meta.discourse.org/t/-/210469#s3-multipart-direct-uploads-4.

An external file store must be set up and enable_direct_s3_uploads must be set to true for this endpoint to function.

Generates batches of presigned URLs for multipart parts

curl -X POST 'https://discourse.example.com/uploads/batch-presign-multipart-parts.json' \
  -H 'Content-Type: application/json' \
  --data-raw '{
  "part_numbers": [
    1,
    2,
    3
  ],
  "unique_identifier": "66e86218-80d9-4bda-b4d5-2b6def968705"
}'

const body = `{
  "part_numbers": [
    1,
    2,
    3
  ],
  "unique_identifier": "66e86218-80d9-4bda-b4d5-2b6def968705"
}`;

const response = await fetch('https://discourse.example.com/uploads/batch-presign-multipart-parts.json', {
  method: 'POST',
  headers: {
    'Content-Type': 'application/json',
  },
  body,
});

const data = await response.text();

import requests

body = '''{
  "part_numbers": [
    1,
    2,
    3
  ],
  "unique_identifier": "66e86218-80d9-4bda-b4d5-2b6def968705"
}'''

response = requests.post(
    'https://discourse.example.com/uploads/batch-presign-multipart-parts.json',
    data=body.encode('utf-8'),
    headers={
        'Content-Type': 'application/json',
    },
)
print(response.text)

Request Body

{
  "part_numbers": [
    1,
    2,
    3
  ],
  "unique_identifier": "66e86218-80d9-4bda-b4d5-2b6def968705"
}

200

{
  "presigned_urls": {
    "1": "https://discourse-martin-uploads-test.s3.us-east-2.amazonaws.com/temp/uploads/default/123abc/123abc.jpg?partNumber=1&uploadId=123456abcd&X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Credential=test&X-Amz-Date=20211222T012336Z&X-Amz-Expires=600&X-Amz-SignedHeaders=host&X-Amz-Signature=abc123"
  }
}

Body

application/json

part_numbersarrayrequired

The part numbers to generate the presigned URLs for, must be between 1 and 10000.

Example

[
  1,
  2,
  3
]

unique_identifierstringrequired

The unique identifier returned in the original /create-multipart request.

Example

66e86218-80d9-4bda-b4d5-2b6def968705

Response

200OKany

external upload initialized

Response fields application/json

presigned_urlsobjectrequired

The presigned URLs for each part number, which has the part numbers as keys.

Example

{
  "1": "https://discourse-martin-uploads-test.s3.us-east-2.amazonaws.com/temp/uploads/default/123abc/123abc.jpg?partNumber=1&uploadId=123456abcd&X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Credential=test&X-Amz-Date=20211222T012336Z&X-Amz-Expires=600&X-Amz-SignedHeaders=host&X-Amz-Signature=abc123"
}

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