File uploads · Ariadne - The first knowledge sharing application in Vietnam

Ariadne implements the GraphQL multipart request specification that describes how file uploads should be implemented by both API clients and servers.

Note
File uploads require python-multipart library:
pip install "ariadne[file-uploads]"

Mục lục bài viết

Enabling file uploads

To enable file uploads on your server, define new a scalar named Upload in your schema:

scalar
 Upload

Next, import upload_scalar from ariadne package and use it during the creation of your executable schema:

from
 ariadne import
 make_executable_schema, upload_scalar schema = make_executable_schema(type_defs, [..., upload_scalar])

You will now be able to use Upload scalar arguments for your operations:

type
 Mutation
 {
    uploadUserImage
(
image
:
 Upload!
)
:
 Boolean!
}

Limitations

The default Upload scalar is a write-only scalar that supports only accessing the value that was passed through the variables. It is not possible to use it as return value for a GraphQL field or set its value in a GraphQL Query:

type
 User
 {
    "This field will fail with ValueError"
    image
:
 Upload}

mutation
 {
    uploadUserImage(
image
:
 "data:text/plain;base64,QXJpYWRuZSByb2NrcyE="
)
}

You are not required to use the Upload scalar implementation provided by Ariadne. You can implement your own if you wish to, so you can (for example) support file literals as base64 data.

Implementation differences

The Python value returned by the Upload scalar is not standardized and depends on your technology stack:

Ariadne’s ASGI support is based on Starlette and hence uploaded files are instances of UploadFile.

Ariadne’s WSGI support uses the python-multipart library that represents uploaded files as instances of File.