How to Push a map into a list in Javascript

Question

So what I am trying to do is take data from a form and push it into my list as a map. It currently says

Cannot read property 'url' of undefined

express = require("express");
app = express();
var bodyParser = require("body-parser");
app.use(express.static("public"));
var imagedata = [
    {url: "...", description: "..."},
    {url: "...", description: "..."}
];
app.use(bodyParser.urlencoded({extended: true}));


app.get("/", function(req, res){
    res.render("home.ejs", {imagedata: imagedata});
});
app.post("/post", function(req, req){
    var NewPost = req.body.url;
    var Description = req.body.description;
    imagedata.push({url: NewPost, description: Description});
    res.redirect("/");

});

Sorry, what I am trying to do is push the NewPost variable and Description variable into the image data list as a map. So it would be like what is currently in the image data list. — Brian Mason, Jun 17 '20 at 16:04
It doesn't say `url` is undefined, it says `req.body` is undefined. — Barmar, Jun 17 '20 at 16:07

score 1 · Answer 1 · answered Jun 17 '20 at 16:19

1

It's saying req.body is undefined because you defined both the request and response as req

Change app.post("/post", function(req, req) to app.post("/post", function(req, res)

answered Jun 17 '20 at 16:19

Adam Neuwirth

529
5
10

The question should just be closed as a typo, no need to post an answer. – Barmar Jun 17 '20 at 16:26

score 0 · Answer 2 · answered Jun 17 '20 at 16:08

0

without seeing the client-side code (the form) I don't really see anything wrong with the code. Try adding console.log to /post:

express = require("express");
app = express();
var bodyParser = require("body-parser");
app.use(express.static("public"));
var imagedata = [
    {url: "...", description: "..."},
    {url: "...", description: "..."}
];
app.use(bodyParser.urlencoded({extended: true}));


app.get("/", function(req, res){
    res.render("home.ejs", {imagedata: imagedata});
});
app.post("/post", function(req, req){
    var NewPost = req.body.url;
    var Description = req.body.description;

    console.log("NewPost:", NewPost, "NewDescription:", Description);

    imagedata.push({url: NewPost, description: Description});

    console.log("imagedata:", imagedata);

    res.redirect("/");

});

to see what data is being given and what has happened to imagedata.

answered Jun 17 '20 at 16:08

Coder100

161
1
12

It's getting an error on the assignment to `NewPost`. It will never get to the `console.log()` line. – Barmar Jun 17 '20 at 16:09
Whats the error? Please include it in your question – Coder100 Jun 17 '20 at 16:10
It's in the beginning of the question: "Cannot read property 'url' of undefined" – Barmar Jun 17 '20 at 16:17
The only place where it tries to read the property `url` is in `req.body.url`, so that implies that `req.body` is undefined. – Barmar Jun 17 '20 at 16:18
ohhh, ok sorry about that can we see the HTML form? – Coder100 Jun 17 '20 at 16:18
BTW, it's not my question. – Barmar Jun 17 '20 at 16:19
Also, at the first line, try adding `console.log(req.body)` to see the full body. – Coder100 Jun 17 '20 at 16:19
We know that will say `undefined`. If you want to log something, try `console.log(req)`. That will show a `Result` object instead of a `Request` object, because of the typo. – Barmar Jun 17 '20 at 16:24

score 0 · Answer 3 · answered Jun 17 '20 at 16:12

as mentioned the question is not really clear but maybe this is what you are looking for although i don't really see the use case for using map instead of an object in this instance. see this post on when to use a map here

express = require("express");
app = express();
var bodyParser = require("body-parser");
app.use(express.static("public"));
var imagedata = [
    {url: "...", description: "..."},
    {url: "...", description: "..."}
];
app.use(bodyParser.urlencoded({extended: true}));


app.get("/", function(req, res){
    res.render("home.ejs", {imagedata: imagedata});
});
app.post("/post", function(req, req){
    var NewPost = req.body.url;
    var Description = req.body.description;
    let map = new Map() 
    map.set('url', NewPost).set('description', Description)
    imagedata.push(map);
    res.redirect("/");

});

He's not using a map. He's just using the word "map" to mean "object". — Barmar, Jun 17 '20 at 16:19
Changing from an object to a map won't fix the error he's getting. It was just a typo in a variable name. — Barmar, Jun 17 '20 at 16:20

How to Push a map into a list in Javascript

3 Answers3