[英]If statement in nodejs not executing in order
下面是 controller.js 脚本。 我在 if 循环“if(changeUserToSellerFlag == 1)”中面临 go 的困难时期,因为这个 if 语句的执行时间远早于这个 if 语句“if (results.Name == "Customer")”。 我不确定为什么执行顺序不是逐行完成。
const { updateUserSellerStatus } = require("./seller.model.js");
const { genSaltSync, hashSync } = require("bcrypt");
const userid = require("../auth/token_validation.js");
const {
updateUserRoleAfterSellerApproval,
getRoleName,
} = require("../users/user.service.js");
module.exports = {
sellerVerify: (req, res) => {
var sellerStatusName;
var changeUserToSellerFlag = 0; // this flag determines if user to seller update is needed or not
approvedByName = req.fullName; //get full name from token_validation.js
approvedByEmail = req.email; //get email from token_validation.js
console.log("Request body is below");
console.log(req.body); // contains body sent by postman
updateUserSellerStatus(
req.body,
approvedByName,
approvedByEmail,
(err, results) => {
if (err) {
console.log(err);
return res.status(500).json({
success: 0,
message: err,
});
}
if (!results) {
console.log(results);
return res.json({
success: 0,
message: err,
});
}
if (req.body.sellerStatus == 3) {
sellerStatusName = "Rejected";
} else if (req.body.sellerStatus == 2) {
sellerStatusName = "Completed";
} else if (req.body.sellerStatus == 1) {
sellerStatusName = "Pending";
}
//verify if user is a seller or not
if (req.userId) {
getRoleName(req.userId, (err, results) => {
console.log("check rolename gettign below");
console.log(results);
if (results.Name == "Customer") {
console.log("User is Customer");
changeUserToSellerFlag = 1;
console.log("flag is :" + changeUserToSellerFlag);
} else if (results.Name == "Seller") {
console.log("User is Seller");
changeUserToSellerFlag = 0;
}
if (err) {
console.log(err);
return res.status(500).json({
success: 0,
message: err,
});
}
});
}
console.log("see flag changed here ", changeUserToSellerFlag);
if (changeUserToSellerFlag == 1) {
console.log("i am here");
//update userrole to seller only if user is not a seller earlier
updateUserRoleAfterSellerApproval(
req.userId,
req.roleId,
(err, results) => {
console.log("result details are bwlo");
console.log(results);
if (err) {
console.log(err);
return res.status(500).json({
success: 0,
message: err,
});
}
if (!results) {
console.log(results);
return res.json({
success: 0,
message: err,
});
}
console.log("Update into UserRole Completed successfully");
},
);
} else {
console.log(
"User is already a seller and dont need to update userrole table",
);
}
console.log(sellerStatusName);
return res.status(200).json({
success: 1,
status: sellerStatusName,
});
},
);
},
};
下面是控制台 output
Request body is below
{ sellerId: 122, sellerStatus: 2 }
see flag changed here 0
User is already a seller and dont need to update userrole table
Completed
check rolename gettign below
TextRow { Name: 'Customer', RoleId: 2 }
User is Customer
flag is :1
其中“用户已经是卖家,不需要更新用户角色表”在“标志为:1”之前首先执行
对我来说,您似乎将异步代码视为同步代码。 在 function 的顶部,您正在调用异步代码的一部分,例如每个数据库查询通常都是异步调用。
getRoleName(req.userId, (err, results) //i assume this is an async call
进程在继续执行之前不会等待上述代码完成,因为它是同步编写的。 因此,它将执行的下一条指令是:
console.log('see flag changed here ', changeUserToSellerFlag);//0
if(changeUserToSellerFlag == 1)//0 --> false
}else{console.log("User is already a seller and dont need to update userrole table");}//so these 3 orders are executed immediately.
之后来自(我假设)的异步调用
getRoleName(req.userId, (err, results)
将完成并调用正确的回调。
作为一个潜在的解决方案:我要么等待任何数据库调用完成,然后再继续。 您可以使用 async - await 调用,其他解决方案也使用 Promises,当然还有回调地狱。
如果我们使用回调,因为您已经在使用它们,它看起来像这样:
updateUserSellerStatus(
req.body,
approvedByName,
approvedByEmail,
(err, results) => {
if (err) {
console.log(err);
return res.status(500).json({
success: 0,
message: err,
});
}
if (!results) {
console.log(results);
return res.json({
success: 0,
message: err,
});
}
if (req.body.sellerStatus == 3) {
sellerStatusName = "Rejected";
} else if (req.body.sellerStatus == 2) {
sellerStatusName = "Completed";
} else if (req.body.sellerStatus == 1) {
sellerStatusName = "Pending";
}
//verify if user is a seller or not
if (req.userId) {
getRoleName(req.userId, (err, results) => {
console.log('check rolename gettign below');
console.log(results);
if (results.Name == "Customer") {
console.log("User is Customer");
changeUserToSellerFlag = 1;
console.log("flag is :" + changeUserToSellerFlag);
} else if (results.Name == "Seller") {
console.log("User is Seller");
changeUserToSellerFlag = 0;
}
console.log('see flag changed here ', changeUserToSellerFlag);
if (changeUserToSellerFlag == 1) {
console.log("i am here");
//update userrole to seller only if user is not a seller earlier
updateUserRoleAfterSellerApproval(
req.userId,
req.roleId,
(err, results) => {
console.log("result details are bwlo");
console.log(results);
if (err) {
console.log(err);
return res.status(500).json({
success: 0,
message: err,
});
}
if (!results) {
console.log(results);
return res.json({
success: 0,
message: err,
});
}
console.log("Update into UserRole Completed successfully");
}
);
} else {
console.log("User is already a seller and dont need to update userrole table");
}
console.log(sellerStatusName);
return res.status(200).json({
success: 1,
status: sellerStatusName,
});
}
if (err) {
console.log(err);
return res.status(500).json({
success: 0,
message: err,
});
}
});
}
);
},
};
我只是移动了下面的代码
console.log('see flag changed here ', changeUserToSellerFlag);
在第一个回调方法中。
我建议将回调地狱的异步性重构为承诺。
令人高兴的是,Node 的util
库中的util.promisify
让回调异步函数非常容易做到这一点。
你最终会得到这样的结果:
const { promisify } = require("util");
const { updateUserSellerStatus } = require("./seller.model.js");
const userid = require("../auth/token_validation.js");
const {
updateUserRoleAfterSellerApproval,
getRoleName,
} = require("../users/user.service.js");
const updateUserSellerStatusP = promisify(updateUserSellerStatus);
const getRoleNameP = promisify(getRoleName);
const updateUserRoleAfterSellerApprovalP = promisify(
updateUserRoleAfterSellerApproval,
);
async function sellerVerify(req) {
var sellerStatusName;
var changeUserToSellerFlag = 0; // this flag determines if user to seller update is needed or not
switch (req.body.sellerStatus) {
case 3:
sellerStatusName = "Rejected";
break;
case 2:
sellerStatusName = "Completed";
break;
case 1:
sellerStatusName = "Pending";
break;
}
const results = await updateUserSellerStatusP(
req.body,
req.fullName,
req.email,
);
if (!results) throw new Error("No results from UUSS");
//verify if user is a seller or not
if (req.userId) {
const roleName = await getRoleNameP(req.userId);
if (roleName.Name === "Customer") {
changeUserToSellerFlag = 1;
} else if (roleName.Name === "Seller") {
changeUserToSellerFlag = 0;
}
}
if (changeUserToSellerFlag) {
console.log("i am here");
//update userrole to seller only if user is not a seller earlier
const results = await updateUserRoleAfterSellerApprovalP(
req.userId,
req.roleId,
);
console.log(results);
if (!results) throw new Error("UURASP results missing");
console.log("Update into UserRole Completed successfully");
} else {
console.log(
"User is already a seller and dont need to update userrole table",
);
}
console.log(sellerStatusName);
return {
success: 1,
status: sellerStatusName,
};
}
module.exports = {
sellerVerify: async (req, res) => {
try {
const result = await sellerVerify(req);
return res.json(result);
} catch (err) {
console.error(err);
return res.status(500).json({
success: 0,
message: err,
});
}
},
};
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