web access - How to call Picture Bed API

I want to call this Picture bed API to upload my picture and return its link.I have translated the official instructional the page into English.And there is a example succeed to use it with Python. I want to use it in Mathematica also, but the parameter (smfile) seem is Python image object.Such as following try.So how to make it?The img in code is

http://o8aucf9ny.bkt.clouddn.com/2016-10-14-17-53-00.png

Try one:

URLExecute["https://sm.ms/api/upload", <|"Method" -> "POST", 
  "smfile" -> img|>]

Try two:

URLExecute["https://sm.ms/api/upload", <|"Method" -> "POST", 
  "smfile" -> 
   FromCharacterCode[ToCharacterCode[ImageData[img], "UTF-8"], 
    "Unicode"]|>]

I think the key of failure is that "smfile" should be a Python object but not a common Mathematica expression or maybe there are other workaround can do this.

Answer

Using URLFetch[]:

smmsUpload[img_, detailed : (True | False) : False] := Module[{raw}, 

    raw = ImportString[URLFetch["https://sm.ms/api/upload", Method -> "POST", 
                                "MultipartElements" -> {{"smfile\"; filename=\"tmp.png", 
                                "image/png"} -> ExportString[img, "PNG"]}], "RawJSON"];
    If[raw === $Failed || Lookup[raw, "code", "error"] =!= "success",
       Echo[raw["msg"]]; Return[$Failed]];
    If[! detailed, raw["data", "url"],
       Grid[Transpose[{{"Dimensions:", "Hash:", "Image Link:", "Delete Link:"}, 
                       MapAt[Hyperlink, FlattenAt[TakeDrop[
                       Lookup[raw["data"], {"width", "height", "hash", "url", "delete"}],
                              2], 2], {{3}, {4}}]}], Alignment -> Left]]]


smmsUpload[ExampleData[{"AerialImage", "Pentagon"}], True]

I couldn't get URLRead[]/URLExecute[] to work, so I'll leave that for somebody else to do.