Passing base64 from flutter to express?

Question

Express.js

I get a photo in the emulator, transfer it to the server, but for some reason an empty body is displayed on the server...
###CLIENT###

saveImgToBase(File img, app) async{
   sharedPreferences = await SharedPreferences.getInstance();
   if (img == null) return;
   String base64Image = base64Encode(img.readAsBytesSync());
   var body={
     "image": base64Image,
     "name": app.id
   };
   await http.post('http://192.168.0.101:5000/api/driver/foto', body: body).then((res) {
     print(res.body);
   }).catchError((err) {
     print(err);
   });
  }

###Server###

app.post('/api/driver/foto',async (req,res)=>{
  console.log(req.body); // ВОТ ТУТ ВЫВОДИТСЯ {} ХОТЯ ДОЛЖЕН ОБЬЕКТ
    try{
    var name = req.body.name;
    var img = req.body.image;
    var realFile = Buffer.from(img,"base64");
    fs.writeFile(name, realFile, function(err) {
      if(err)
       console.log(err);
     });
     res.send("OK");    
  }catch(err){
    res.status(422).json({error:"Не сохранилось в папку, напишите администратору."});
  }
});