How do I POST call my flask api from reactjs and send the data without converting it to json

I'm trying to send data from my reactjs app to flask api. I'm returning the following from function App()

 
    return(
    <div>
        <form onSubmit={handleSubmit} action="http://localhost:5000/mongodb" method="POST">
            <fieldset>
                <label>
                    <p>User ID:</p>
                    <input type="text" name="uid"/>
                    <button type="submit">Submit</button>
                </label>
            </fieldset>
        </form>
        <h1...

where uid is a 4 digit number

I'm trying to accept the same from my flask api in this way

@app.route('/mongodb',methods = ['POST'])
def mongo_rec():
    try:
        if(request.method == 'POST'):
            uid = request.form('UID')

I don't know where I've gone wrong , kindly point it out.