# Flask Get POST Request Data: Form and JSON Examples

> Access POST request data in Flask using request.form for form submissions and request.json for JSON payloads, with content-type detection and fallback parsing

**URL:** https://sentry.io/answers/flask-getting-post-data/

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## The Problem

How can you access the data that has been sent to a Flask app through a POST request?

## The Solution

A user can submit various types of data using a POST request. Depending on the type of data, Flask uses different ways to extract and parse the data before storing it in the global [request object](https://flask.palletsprojects.com/en/latest/api/?highlight=request#flask.request).

We're going to take a look at two of the most common types of data. You can read more about how Flask handles other kinds of data on [the official documentation](https://flask.palletsprojects.com/en/latest/api/?highlight=request#flask.Request).

### Form Data

When a user fills out a form on the frontend of a web app and hits submit, the browser sends that data to our app. The data is submitted using a POST request with the [Content-Type](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Type) header set to `multipart/form-data`.

When Flask receives form data, it parses and stores it in the `form` property of the request object. The `form` property is an [`ImmutableMultiDict`](https://werkzeug.palletsprojects.com/en/latest/datastructures/#werkzeug.datastructures.ImmutableMultiDict "(in Werkzeug v2.2.x)"), which implements all standard dictionary methods.

Let's say a user submits a form with two input fields: name and age. We can extract form data, like so:

```python
from flask import Flask, request
# ...

@app.route('/form_example', methods=['POST'])
def handle_form():
	print(request.form.get('name'))
	print(request.form.get('age'))
	return request.form
```

### JSON Data

The most commonly used format of the incoming data is JSON. Flask stores the JSON data in the `json` property of the request object. We can access the data like so:

```python
from flask import Flask, request
# ...

@app.route('/json_example', methods=['POST'])
def handle_json():
    data = request.json
    print(data.get('name'))
    print(data.get('age'))
    return data
```

An important point to remember is that the `json` will only contain the data if the `Content-Type` header is set to `application/json`.

We can use the `headers` attribute of the request object to check the `Content-Type`, like so:

```python
from flask import Flask, request
# ...

@app.route('/json_example', methods=['POST'])
def handle_json():
  content_type = request.headers.get('Content-Type')
  if (content_type == 'application/json'):
    ...
  else:
    return "Content type is not supported."
```

A better way to check is to use the [`is_json`](https://flask.palletsprojects.com/en/latest/api/?highlight=json#flask.Request.is_json) property of the request object:

```python
from flask import Flask, request
# ...

@app.route('/json_example', methods=['POST'])
def handle_json():
  if request.is_json:
    ...
  else:
    ...
```

If the `Content-Type` header is not set correctly, Flask will store the data as a string (even if it is JSON) in the `data` property of the request object.

We can use Flask's `json` module to convert the string back to JSON, like so:

```python
from flask import Flask, request, json
# ...

@app.route('/string_example', methods=['POST'])
def handle_non_json():
	data = json.loads(request.data)
	return data
```

The good thing about using the `json` module is that it can extract the data correctly even when it receives a request with `Content-Type` header set to `application/json`.

Either of the following two requests will result in the same response:

```bash
$ curl -X POST -H "Content-type: application/json" -d "{\"name\" : \"John\", \"age\" : \"5\"}" "localhost:5000/string_example"
```

```bash
$ curl -X POST -H "Content-type: text/plain" -d "{\"name\" : \"John\", \"age\" : \"5\"}" "localhost:5000/string_example"
```

It is best to use this solution in situations where we don't know which header will be sent to our app.

### Further Reading

[How do you get the Data Received in a Flask Request?](https://sentry.io/answers/get-data-flask-request/)

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*Source: [sentry.io/answers/flask-getting-post-data/](https://sentry.io/answers/flask-getting-post-data/)*