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This article mainly introduces "how nodejs library express receives inbound json requests". In daily operation, I believe many people have doubts about how nodejs library express receives inbound json requests. Xiaobian consulted all kinds of materials and sorted out simple and easy-to-use operation methods. I hope it will be helpful to answer the questions of "how nodejs library express receives inbound json requests". Next, please follow the editor to study!

A few simple lines of code like this create a web server:

Var express = require ('express'); var app = express (); var server = require (' http') .Server (app); var bodyParser = require ('body-parser'); app.use (bodyParser.json ({limit:' 10mbbeer, extended: true}))

Then use app.post ("/ getSimilarImage", function (req, res) {

/ / Business logic is written here

});

You can receive json requests. The question is, how does the json string I send through postman be handled by nodejs's express library?

To debug, the parameter path of trim_prefix is the API endpoint I tested in postman:

Call the handle_request method of layer, which is similar to the HANDLE_REQUEST method of IF_HTTP_EXTENSION in SAP ABAP.

Middleware in express, query.js:

This middleware also uses a direct comparison with undefined:

Here we are ready to start reading inbound json:

Read the data through the callback function onData registered on stream:

Read 65018 bytes of data:

Write the read data to buffer:

At the same time, it is decoded by decoder on line 252:

When all the data of inbound message is read, the End event is triggered and the registered callback done function is executed:

At this point, all read data is stored in the variable body:

This json.js is responsible for parsing the string contained in the body variable into a json object:

Thus, the library body-parser ultimately uses the native JSON.parse API to accomplish the parsing task.

At this point, the study on "how the nodejs library express receives inbound json requests" is over. I hope to be able to solve your doubts. The collocation of theory and practice can better help you learn, go and try it! If you want to continue to learn more related knowledge, please continue to follow the website, the editor will continue to work hard to bring you more practical articles!

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