Stripe.Net Introduction

Syntax#

var stripeSubscriptionOptions = new StripeSubscriptionCreateOptions();

//create a variable to hold options object
```
        stripeSubscriptionOptions.Quantity = model.update;
```
//example option of quantity of seats for a subscription
```
        var subscriptionService = new StripeSubscriptionService();
```
//create a service to make the API call
```
        var stripeSubscription = subscriptionService.Create(user.CustomerIdentifier, planId,
```
stripeSubscriptionOptions);

// service.create( string CustID, string PlanID, Object SubscriptionOptions)

//Customer ID should be saved from your database, you can retrieve planID from stripe using a PlanService and create the options object like above. If you NuGet the Stripe.Net intellisense works for these as well.

Remarks#

Somewhere in the beginning of your controller you should call

StripeConfiguration.SetApiKey(YOUR SECRET KEY VAR);

and for data safety it should be a value hidden as a secret in appsettings

if you do not set the API key you will not be able to modify subscriptions or create customers

Starting with Stripe.Net in ASP.Net Core 1.0

https://github.com/jaymedavis/stripe.net is a great starting point.
Assuming you are using MVC w/Razor you need to have a few things in your View page

<script type="text/javascript" src="https://js.stripe.com/v2/"></script>

This script calls upon the stripe.js to handle creating a token.

<script type="text/javascript">
        Stripe.setPublishableKey('YOUR STRIPE PUBLIC KEY');

var stripeResponseHandler = function (status, response) {
    var $form = $('#payment-form');

    if (response.error) {
        // Show the errors on the form
        $form.find('.payment-errors').text(response.error.message);
        $form.find('button').prop('disabled', false);
    } else {
        // token contains id, last4, and card type
        var token = response.id;
        // Insert the token into the form so it gets submitted to the server
        $form.append($('<input type="hidden" asp-for="stripeToken" />').val(token));
        // and re-submit
        $form.get(0).submit();
    }
};

jQuery(function ($) {
    $('#payment-form').submit(function (e) {
        var $form = $(this);

        // Disable the submit button to prevent repeated clicks
        $form.find('button').prop('disabled', true);

        Stripe.card.createToken($form, stripeResponseHandler);

        // Prevent the form from submitting with the default action
        return false;
    });
});
</script>

To add the token to a model make sure you change

$form.append($('<input type="hidden" asp-for="stripeToken" />').val(token));

to reflect your model. The form should look like this one.

 <form asp-action="confirm" method="POST" id="payment-form">
            <span class="payment-errors"></span>

            <div class="row">
                <label>
                    <span>Card Number</span>
                    <input type="text" data-stripe="number" value="4242424242424242">
                </label>
            </div>

            <div class="row">
                <label>
                    <span>CVC</span>
                    <input type="text" data-stripe="cvc" value="123">
                </label>
            </div>

            <div class="row">
                <label>
                    <span>Expiration (MM/YYYY)</span>
                    <input type="text" data-stripe="exp-month" value="12">
                </label>
                <input type="text" data-stripe="exp-year" value="2020">
            </div>

            <button type="submit">Buy Now</button>
        </form>

The controller takes one of the users and checks for a CustomerIdentifier which is the Id of the customer given by stripe. If this isn’t saved in the database then it works on creating a customer for them

 public async Task<IActionResult> Index(OrderViewModel model)   //HOME PAGE beginning of managing subs
    {
        //get the user and their ID
        var user = await GetCurrentUserAsync();
        var userId = user?.Id;
        // If they have a customer Identifier use it
        if (!string.IsNullOrEmpty(user.CustomerIdentifier))  //eventually if user has a saved card as well
        {
            //Create the API call to subscription and put its response in a list
            var subscriptionService = new StripeSubscriptionService();
            IEnumerable<StripeSubscription> response = subscriptionService.List(user.CustomerIdentifier);

            ViewBag.Subscription = response;

            ViewBag.Customer = user.CustomerIdentifier;


        }
        ModelState.Clear();
        return View(model);
    }
 public async Task<IActionResult> Confirm(OrderViewModel model, string stripeToken)  // CREATE CHARGE NO CARD/ NO CUSTOMER
    {
        model.stripeToken = stripeToken;
        //get the user and their ID
        var user = await GetCurrentUserAsync();
        var userId = user?.Id;
        var planId = "YOUR PLAN ID HERE";  //plan ID only 1 atm but will need to be a dynamic plan ID list later
        // If they have a customer Identifier use it
        if (!string.IsNullOrEmpty(user.CustomerIdentifier))
        {
            //Create the API call to subscription and put its response in a list
            //Use the subscription options to apply a quantity to the initial subscription for seats
            var stripeSubscriptionOptions = new StripeSubscriptionCreateOptions();
            stripeSubscriptionOptions.Quantity = model.update;
            var subscriptionService = new StripeSubscriptionService();
            var stripeSubscription = subscriptionService.Create(user.CustomerIdentifier, planId, stripeSubscriptionOptions);
            //save Subscriptions data here

            ModelState.Clear();
            //await SaveSubscription(stripeSubscription, user);
            await _userManager.UpdateAsync(user);
        }
        else // Customer is new and doesn't have an ID
        {
            //Create API options
            var customer = new StripeCustomerCreateOptions();
            
            // Add option values
            customer.Email = $"{user.Email}";
            customer.Description = $"{user.Email} [{userId}]";
            customer.PlanId = planId;
            
            customer.SourceToken = model.stripeToken;
            //Make the call to create the customer with the creation options
            var customerService = new StripeCustomerService();
            StripeCustomer stripeCustomer = customerService.Create(customer);

            //save the customer ID
            user.CustomerIdentifier = stripeCustomer.Id;

            //create card update options and add billing info
            var cardOptions = new StripeCardUpdateOptions();
            cardOptions.AddressLine1 = model.BillingInfo.AddressL1;
            cardOptions.AddressLine2 = model.BillingInfo.AddressL2;
            cardOptions.AddressCountry = model.BillingInfo.Country;
            cardOptions.AddressCity = model.BillingInfo.City;
            cardOptions.AddressState = model.BillingInfo.State;
            cardOptions.AddressZip = model.BillingInfo.Zip;
            cardOptions.Name = model.BillingInfo.Name;
            var cardUpdate = new StripeCardService();
            // get the customer card ID and then update the card info
            StripeCustomer customerCardGet = customerService.Get(user.CustomerIdentifier);
            var cardId = customerCardGet.DefaultSourceId;
            StripeCard Card = cardUpdate.Update(user.CustomerIdentifier, cardId, cardOptions);


            //save Subscriptions data here
            //user.ConcurrentUsers = Stripe Quantity
            
            ModelState.Clear();

            await _userManager.UpdateAsync(user);
           
        }
        ViewBag.Success = "confirm";
        return View("Success");
    }

This particular example includes some of the extras like taking billing information in the controller. If you want this just add it to the form on the view and create a model to hold it.