微信小程序云调用限时秒杀

Page({
  data: {
    productId: '12345',
    stock: 100
  },
  startSeckill: function() {
    wx.cloud.callFunction({
      name: 'seckill',
      data: {
        productId: this.data.productId
      },
      success: res => {
        if (res.result.success) {
          wx.showToast({
            title: '秒杀成功',
            icon: 'success'
          });
        } else {
          wx.showToast({
            title: '秒杀失败，库存不足',
            icon: 'none'
          });
        }
      },
      fail: console.error
    });
  }
});

const cloud = require('wx-server-sdk');
cloud.init();
const db = cloud.database();

exports.main = async (event, context) => {
  const { productId } = event;
  const productRef = db.collection('products').doc(productId);

  try {
    const res = await productRef.runTransaction(async transaction => {
      const product = await transaction.get(productRef);
      if (product.data.stock > 0) {
        await transaction.update(productRef, { stock: product.data.stock - 1 });
        return { success: true };
      } else {
        return { success: false };
      }
    });

    return res;
  } catch (e) {
    console.error(e);
    return { success: false };
  }
};