How could get the upload image file?

[lazywking]

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I have a very simple workflow: start node and code node, in the start node, I create a input variable image_file as single image file uploaded from local(the deployed Dify in local docker) . start node output as follow:
{
"image_file": {
"dify_model_identity": "dify__file",
"id": null,
"tenant_id": "c61e32ec-eae9-47b8-9524-40e0364cac13",
"type": "image",
"transfer_method": "local_file",
"remote_url": "",
"related_id": "eec6e950-d5e0-4237-b560-56e8feeebea9",
"filename": "test2.jpg",
"extension": ".jpg",
"mime_type": "image/jpeg",
"size": 310236,
"url": "/files/eec6e950-d5e0-4237-b560-56e8feeebea9/file-preview?timestamp=1741159719&nonce=b24f7de19c9c1b252dc9af85308c2d40&sign=m-zn7k-UqafQUWVPKtU8yTmgywqvaIaJ1SZuAPdIcOk="
},
"sys.files": [],
"sys.user_id": "83cd55c2-ae7f-49d2-8dcb-9f0fc365156e",
"sys.app_id": "c8e99bd0-f948-4238-8112-a163acb951bc",
"sys.workflow_id": "82dd7532-a320-467e-a29c-85a16b2419b5",
"sys.workflow_run_id": "a63c7239-82a3-4b06-b4ae-85597d6051ee"
}
Now In code node, I want to get the file from image_file, I havn't find noway to do it. if I set a variable to start/image_file.url; in the code node , I get empty! how can I deal with it? I want to read the file and encode the file content into base64.