How to use (reference) the uploaded file to a media(video) type? I have read https://www.drupal.org/node/2941420 and I can upload a image file then use it in article.

But I can not use it as video field after I upload a video file.

My Drupal version is 8.6.0-beta2.

I use the media type ( Drupal 8 core module) for my video field, this is a Entity reference.

When I use

POST  http://www.myhots.com/file/upload/media/video/field_media_video_file?_fo...


I get the response as the end shows (the fid =47)

{
    "message":"Unprocessable Entity: validation failed.
field_user_video.0.target_id: The referenced entity (media: 47) does not exist.
"
}


Then I use it :

curl -X PATCH -H 'Content-Type: application/json' -H 'X-CSRF-Token:YYYYYYYYYYYYYYYYYYYY' -H 'Authorization: Basic XXXXXXXXXXX=' -i 'http://www.myhost.com/node/5?_format=json' --data '{

"type":[
    {
        "target_id":"user_video",
        "target_type":"node_type"
    }
],
"field_user_video":[
    {
        "target_id":47,
        "target_type":"media"
    }
]


}

The response is as follows:

{
    "message":"Unprocessable Entity: validation failed.
field_user_video.0.target_id: The referenced entity (media: 47) does not exist.
"
}


Which information should I use to patch it? It seems that the "fid" is not correct.

Maybe I need  "target_id " of "media“， but there is no response after I upload a video file, any suggestion?

"field_user_video": [{
  "target_id": 3,
  "target_type": "media",
  "url": "\/d86\/media\/3"
}]

'

{
"fid":[
    {
        "value":47
    }
],
"uuid":[
    {
        "value":"cf69fac4-5ba2-4861-9cce-a959dee3c480"
    }
],
"langcode":[
    {
        "value":"en"
    }
],
"uid":[
    {
        "target_id":1,
        "target_type":"user",
        "target_uuid":"c2b09ff8-345a-43fa-b9ae-68af0c9cd3ea",
        "url":"/d86/user/1"
    }
],
"filename":[
    {
        "value":"example2.mp4"
    }
],
"uri":[
    {
        "value":"public://2018-08/example2.mp4",
        "url":"/d86/sites/default/files/2018-08/example2.mp4"
    }
],
"filemime":[
    {
        "value":"video/mp4"
    }
],
"filesize":[
    {
        "value":6320348
    }
],
"status":[
    {
        "value":false
    }
],
"created":[
    {
        "value":"2018-08-31T03:04:20+00:00",
        "format":"Y-m-d\TH:i:sP"
    }
],
"changed":[
    {
        "value":"2018-08-31T03:04:20+00:00",
        "format":"Y-m-d\TH:i:sP"
    }
]
}
after two days trying , i find the solution myself.
shortly , 

first,  post file , get the fid.

second, post a media , get the Mid (media id)

third , post a node ,use the Mid 

I omit the second step.