无法获取 js object 的特定属性

Question

I am working with ejs, mongodb and express. In ejs file, I have set value of an Edit button to the the js object passed into the ejs file so that I can query required data after in express after the Edit button makes a post request to a route. EJS edit button code:

<% listOfRecords.forEach((singleRecord)=>{ %>
        <div class="card card-body">
            <form method="post">
                    <button formaction="/edit" class="btn btn-success btn-sm" name="editBtn" value="<%=singleRecord%>">Edit</button>            
            </form>
        </div>  
    <% }); %> 

However, I am able console log the js object by the following code in express:

app.post('/edit', (req, res)=>{
    console.log(req.body.editBtn);
});

The output of the above code is:

{
  _id: 60605148a1fba61fd8f2446f,
  title: 'asdf',
  author: 'sadf',
  class_section: 'asfd',
  dateIssued: 2021-03-01T00:00:00.000Z,
  __v: 0
}

But when I try doing this: console.log(req.body.editBtn.title); it shows the error, undefined

What am I doing wrong in this?

Answer 1

I don't think we have enough information. The code from my perspective looks fine. It should work.

What you could try doing is getting the attribute by doing console.log(req.body.editBtn['title']); instead of console.log(req.body.editBtn.title); .

You could also try destructuring the title: const { title } = req.body.editBtn .

Although these should theoretically not work? Maybe something else in your code is wrong ?

Edit:

If req.body.editBtn is a string then try JSON.parse(req.body.editBtn); then get the attribute you want.

Answer 2

The real problem was that req.body.editBtn was in String format. So to make this work, change in EJS file would be:

<button formaction="/edit" class="btn btn-success btn-sm" name="editBtn" value="<%=JSON.stringify(singleRecord)%>">Edit</button>

This shall convert js object into a string properly and then in express file, the change is:

let editBtn = req.body.editBtn;
let info = JSON.parse(editBtn);

Now I can access any property of the object because it was converted to and from string properly.

Answer 3

you should get attributes from JSON.parse method's output, rather than req.body.editBtn which is still string.

app.post('/edit', (req, res)=>{
    const data = JSON.parse(req.body.editBtn);
    // console.log(req.body.editBtn);
    console.log(data.title);
    console.log(data.author);
    // ....
});