商户图片上传

部分微信支付业务指定商户需要使用图片上传API来上报图片信息，从而获得必传参数的值：图片MediaID 。 官方文档

const { Multipart } = require('wechatpay-axios-plugin')
const { createReadStream } = require('fs')
const { basename } = require('path');

let localFilePath = '/path/to/merchant-image-file.jpg'
const stream = createReadStream(localFilePath)
const media = new Multipart()
  .append('meta', JSON.stringify({
    filename: basename(localFilePath),
    sha256: 'from upstream or local calculated',
  }))
  .append('file', stream, basename(localFilePath))

wxpay.v3.merchant.media.upload.post(media)
.then(
  ({ 
    data: {
      media_id,
    },
  }) => ({
    media_id,
  })
)