CODEWITHSUNDEEP
javascriptjqueryhtmljsonforms
stratis
stratis

Reputation: 8042

How to send a JSON object using html form data

So I've got this HTML form:

<html>
<head><title>test</title></head>
<body>
    <form action="myurl" method="POST" name="myForm">
        <p><label for="first_name">First Name:</label>
        <input type="text" name="first_name" id="fname"></p>

        <p><label for="last_name">Last Name:</label>
        <input type="text" name="last_name" id="lname"></p>

        <input value="Submit" type="submit" onclick="submitform()">
    </form>
</body>
</html>

Which would be the easiest way to send this form's data as a JSON object to my server when a user clicks on submit?

UPDATE: I've gone as far as this but it doesn't seem to work:

<script type="text/javascript">
    function submitform(){
        alert("Sending Json");
        var xhr = new XMLHttpRequest();
        xhr.open(form.method, form.action, true);
        xhr.setRequestHeader('Content-Type', 'application/json; charset=UTF-8');
        var j = {
            "first_name":"binchen",
            "last_name":"heris",
        };
        xhr.send(JSON.stringify(j));

What am I doing wrong?

Upvotes: 205

Views: 751454

Answers (11)

KARTHIKEYAN.A
KARTHIKEYAN.A

Reputation: 20088

We can attach file and json in the following way

const api = (app, body) => getOptions({
    body,
    headers: {
        'Content-Type': 'application/json',
    },
    url: 'http://localhost:2030'
})

function multiPart(payload) {
    const formData = new FormData()
    formData.append('fileNames', payload.attachments)
    formData.append('fixedIncomeSubAccountRequest', JSON.stringify(payload.body))
    return formData
}

api(app, multiPart(payload)).then(response => console.log(respone))

Upvotes: 0

Exo Flame
Exo Flame

Reputation: 147

Well came across this again and there is no fetch copy pasta so though id add my own solution that I dug up.

This uses vanilla fetch and built in browser features.

/**
 * Helper function for POSTing data as JSON with fetch.
 *
 * @param {Object} options
 * @param {string} options.url - URL to POST data to
 * @param {FormData} options.formData - `FormData` instance
 * @return {Object} - Response body from URL that was POSTed to
 */
var postFormDataAsJson = async({
  url,
  formData
}) => {
  const plainFormData = Object.fromEntries(formData.entries());
  const formDataJsonString = JSON.stringify(plainFormData);

  const fetchOptions = {
    method: "POST",
    headers: {
      "Content-Type": "application/json",
      Accept: "application/json",
    },
    body: formDataJsonString,
  };


  alert("about to post" + formDataJsonString)
  const response = await fetch(url, fetchOptions);

  if (!response.ok) {
    const errorMessage = await response.text();
    throw new Error(errorMessage);
  }

  return response.json();
}
/**
 * Event handler for a form submit event.
 * @see https://developer.mozilla.org/en-US/docs/Web/API/HTMLFormElement/submit_event
 * @example const exampleForm = document.getElementById("example-form");
 *          exampleForm.addEventListener("submit", handleFormSubmit);
 * @param {SubmitEvent} event
 */
var handleFormSubmit = async(event) => {
  event.preventDefault();
  const form = event.currentTarget;
  const url = form.action;

  try {
    const formData = new FormData(form);
    const responseData = await postFormDataAsJson({
      url,
      formData
    });
    console.log({
      responseData
    });
  } catch (error) {
    console.error(error);
  }
}

document.querySelector("form[name='myForm']")
  .addEventListener("submit", handleFormSubmit)
<html>

<head>
  <title>test</title>
</head>

<body>
  <form action="myurl" method="POST" name="myForm">
    <p><label for="first_name">First Name:</label>
      <input type="text" name="first_name" id="fname"></p>

    <p><label for="last_name">Last Name:</label>
      <input type="text" name="last_name" id="lname"></p>

    <input value="Submit" type="submit"> 
    </form>
  </body>

  </html>

sauces

https://bsjs.sgol.pub/doc/public_src_bs.js#line977

postFormDataAsJson jsdoc

less form dependent sendJson

Upvotes: 2

GIA
GIA

Reputation: 1706

If you want to use pure javascript in 2022...

const ajax = async (config) => {
    const request = await fetch(config.url, {
        method: config.method,
        headers: {
            'Accept': 'application/json',
            'Content-Type': 'application/json'
        },
        body: JSON.stringify(config.payload)
    });
    response = await request.json();
    console.log('response', response)
    return response
}

// usage
response = ajax({
    method: 'POST',
    url: 'example.com',
    payload: {"name": "Stackoverflow"}
})

Upvotes: 4

SachinGutte
SachinGutte

Reputation: 7055

Get complete form data as array and json stringify it.

var formData = JSON.stringify($("#myForm").serializeArray());

You can use it later in ajax. Or if you are not using ajax; put it in hidden textarea and pass to server. If this data is passed as json string via normal form data then you have to decode it. You'll then get all data in an array.

$.ajax({
  type: "POST",
  url: "serverUrl",
  data: formData,
  success: function(){},
  dataType: "json",
  contentType : "application/json"
});

Upvotes: 186

Sorter
Sorter

Reputation: 10220

Use FormData API

  1. Capture the form data using FormData API formData= new FormData(form)
  2. Convert it into JSON using JSON.stringify(Object.fromEntries(formData))
  3. Send this strigified json as ajax payload
var form = document.getElementById('myForm');
form.onsubmit = function(event){
        var xhr = new XMLHttpRequest();
        var formData = new FormData(form);
        //open the request
        xhr.open('POST','http://localhost:7000/tests/v1.0/form')
        xhr.setRequestHeader("Content-Type", "application/json");

        //send the form data
        xhr.send(JSON.stringify(Object.fromEntries(formData)));

        xhr.onreadystatechange = function() {
            if (xhr.readyState == XMLHttpRequest.DONE) {
                form.reset(); //reset form after AJAX success or do something else
            }
        }
        //Fail the onsubmit to avoid page refresh.
        return false; 
    }

Taken from an article I wrote here: https://metamug.com/article/html5/ajax-form-submit.html

Upvotes: 21

Avi Tshuva
Avi Tshuva

Reputation: 264

The micro-library field-assist does exactly that: collectValues(formElement) will return a normalized json from the input fields (that means, also, checkboxes as booleans, selects as strings,etc).

Upvotes: 0

Israelm
Israelm

Reputation: 1675

I found a way to pass a JSON message using only a HTML form.

This example is for GraphQL but it will work for any endpoint that is expecting a JSON message.

GrapqhQL by default expects a parameter called operations where you can add your query or mutation in JSON format. In this specific case I am invoking this query which is requesting to get allUsers and return the userId of each user.

{ 
 allUsers 
  { 
  userId 
  }
}

I am using a text input to demonstrate how to use it, but you can change it for a hidden input to hide the query from the user.

<html>
<body>
    <form method="post" action="http://localhost:8080/graphql">
        <input type="text" name="operations" value="{&quot;query&quot;: &quot;{ allUsers { userId } }&quot;, "variables":  {}}"/>
        <input type="submit" />
    </form>
</body>
</html>

In order to make this dynamic you will need JS to transport the values of the text fields to the query string before submitting your form. Anyway I found this approach very interesting. Hope it helps.

Upvotes: -2

Hasan A Yousef
Hasan A Yousef

Reputation: 24948

You can try something like:

<html>
<head>
    <title>test</title>
</head>

<body>
    <form id="formElem">
        <input type="text" name="firstname" value="Karam">
        <input type="text" name="lastname" value="Yousef">
        <input type="submit">
    </form>
    <div id="decoded"></div>
    <button id="encode">Encode</button>
    <div id="encoded"></div>
</body>
<script>
    encode.onclick = async (e) => {
        let response = await fetch('http://localhost:8482/encode', {
                method: 'GET',
                headers: {
                    'Content-Type': 'application/json',
                },
        })

        let text = await response.text(); // read response body as text
        data = JSON.parse(text);
        document.querySelector("#encoded").innerHTML = text;
      //  document.querySelector("#encoded").innerHTML = `First name = ${data.firstname} <br/> 
      //                                                  Last name = ${data.lastname} <br/>
      //                                                  Age    = ${data.age}`
    };

    formElem.onsubmit = async (e) => {
      e.preventDefault();
      var form = document.querySelector("#formElem");
     // var form = document.forms[0];

        data = {
          firstname : form.querySelector('input[name="firstname"]').value,
          lastname : form.querySelector('input[name="lastname"]').value,
          age : 5
        }

        let response = await fetch('http://localhost:8482/decode', {
                method: 'POST', // or 'PUT'
                headers: {
                    'Content-Type': 'application/json',
                },
                body: JSON.stringify(data),
        })

        let text = await response.text(); // read response body as text
        document.querySelector("#decoded").innerHTML = text;
    };
</script>
</html>

Upvotes: 10

orafaelreis
orafaelreis

Reputation: 2881

I'm late but I need to say for those who need an object, using only html, there's a way. In some server side frameworks like PHP you can write the follow code:

<form action="myurl" method="POST" name="myForm">
        <p><label for="first_name">First Name:</label>
        <input type="text" name="name[first]" id="fname"></p>

        <p><label for="last_name">Last Name:</label>
        <input type="text" name="name[last]" id="lname"></p>

        <input value="Submit" type="submit">
    </form>

So, we need setup the name of the input as object[property] for got an object. In the above example, we got a data with the follow JSON:

{
"name": {
  "first": "some data",
  "last": "some data"
 }
}

Upvotes: 4

tdjprog
tdjprog

Reputation: 719

you code is fine but never executed, cause of submit button [type="submit"] just replace it by type=button

<input value="Submit" type="button" onclick="submitform()">

inside your script; form is not declared.

let form = document.forms[0];
xhr.open(form.method, form.action, true);

Upvotes: 4

Quentin
Quentin

Reputation: 943556

HTML provides no way to generate JSON from form data.

If you really want to handle it from the client, then you would have to resort to using JavaScript to:

  1. gather your data from the form via DOM
  2. organise it in an object or array
  3. generate JSON with JSON.stringify
  4. POST it with XMLHttpRequest

You'd probably be better off sticking to application/x-www-form-urlencoded data and processing that on the server instead of JSON. Your form doesn't have any complicated hierarchy that would benefit from a JSON data structure.

Update in response to major rewrite of the question…

  • Your JS has no readystatechange handler, so you do nothing with the response
  • You trigger the JS when the submit button is clicked without cancelling the default behaviour. The browser will submit the form (in the regular way) as soon as the JS function is complete.

Upvotes: 74

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