Use middleware in nodejs + express to improve code reuse

Use middleware in nodejs + express to improve code reuse

When using nodejs + express + mysql as the background, many requests involving user information must first judge the token in the request (username + timestamp + random number using random string encrypted by sha1) valid or not.

In the beginning, the token is added to the processing of each request. (Write n times, head pumping)

The Code is as follows:

 

// Modify the project status router. post ('/change-Project', validToken, function (req, res, next) {var db = req. db; var token = req. query. token; var id = req. query. id; var projectStatus = req. query. status; var data = {status: false, message:} db. getConnection (function (err, conn) {if (err) {sendData (req, res, next, conn, err);} else {db. query ('select * FROM user WHERE user_token = '+ token + '', function (err, row) {// determine whether token is valid I F (err) {sendData (req, res, next, conn, err);} else {if (row. length = 0) {sendData (req, res, next, conn, please log on); // the error message returned is invalid} else {// modify the status database if the token is valid. query ('Update project SET project_status = '+ projectStatus + 'where project_id =' + id + '', function (err, row) {if (err) {sendData (req, res, next, conn, err);} else {data. message = (row. affectedRows = 1 )? Modification succeeded: Modification failed; data. status = (row. affectedRows = 1 )? True: false; res. send ({'data': data}); conn. release ();}})}}})}})})

 

Token verification is redundant because it must be written in each function to be verified.

This part of verification token is proposed to become a middleware.

The Code is as follows:

 

Function validToken (req, res, next) {var db = req. db; var userToken = req. query. token; db. getConnection (function (err, conn) {if (err) {sendData (req, res, next, conn, err);} else {db. query ('select * FROM user WHERE user_token = '+ userToken + '', function (err, row) {if (err) {sendData (req, res, next, conn, err);} else {if (row. length = 0) {sendData (req, res, next, conn, please log on);} else {next ();}}})}})} // when an error occurs, return a data object function sendData (req, res, next, conn, message) {var data = {message:, // error message status: false // status} data. message = message; conn. release (); res. send ({data: data });}

Then, the middleware is applied to the corresponding route,

 

In this way, the first route is changed to the following example:

 

// Modify the project status router. post ('/change-Project', validToken, function (req, res, next) {var db = req. db; var token = req. query. token; var id = req. query. id; var projectStatus = req. query. status; var data = {status: false, message:} db. getConnection (function (err, conn) {if (err) {sendData (req, res, next, conn, err);} else {db. query ('Update project SET project_status = '+ projectStatus + 'where project_id =' + I D + '', function (err, row) {if (err) {sendData (req, res, next, conn, err);} else {data. message = (row. affectedRows = 1 )? Modification succeeded: Modification failed; data. status = (row. affectedRows = 1 )? True: false; res. send ({'data': data}); conn. release ();}})}})})

In this way, you do not need to repeat the writing to verify the token and can reuse it directly.

 

In fact, the layer-by-layer nesting (if (err) error processing else query) for database query can also be solved through middleware.