Creating an external checkout process

Occasionally, we get asked whether it is possible to just use pretix’ powerful backend as a ticketing engine but use a fully-customized checkout process that only communicates via the API. This is possible, but with a few limitations. If you go down this route, you will miss out on many of pretix features and safeguards, as well as the added flexibility by most of pretix’ plugins. We strongly recommend to talk this through with us before you decide this is the way to go.

However, this is really useful if you need to tightly integrate pretix into existing web applications that e.g. control the pricing of your products in a way that cannot be mapped to pretix’ product structures.

Creating orders

After letting your user select the products to buy in your application, you should create a new order object inside pretix. Below, you can see an example of such an order, but most fields are optional and there are some more features supported. Read Creating orders to learn more about this endpoint.

Please note that this endpoint assumes trustworthy input for the most part. By default, the endpoint checks that you do not exceed any quotas, do not sell any seats twice, or do not use any redeemed vouchers. However, it will not complain about violation of any other availability constraints, such as violation of time frames or minimum/maximum amounts of either your product or event. Bundled products will not be added in automatically and fees will not be calculated automatically.

POST /api/v1/organizers/democon/events/3vjrh/orders/ HTTP/1.1
Host: test.pretix.eu
Accept: application/json, text/javascript
Content-Type: application/json
Authorization: 

{
  "email": "dummy@example.org",
  "locale": "en",
  "sales_channel": "web",
  "payment_provider": "banktransfer",
  "invoice_address": {
    "is_business": false,
    "company": "Sample company",
    "name_parts": {"full_name": "John Doe"},
    "street": "Sesam Street 12",
    "zipcode": "12345",
    "city": "Sample City",
    "country": "US",
    "state": "NY",
    "internal_reference": "",
    "vat_id": ""
  },
  "positions": [
    {
      "item": 21,
      "variation": null,
      "attendee_name_parts": {
        "full_name": "Peter"
      },
      "answers": [
        {
          "question": 1,
          "answer": "23",
          "options": []
        }
      ],
      "subevent": null
    }
  ],
  "fees": []
}

You will be returned a full order object that you can inspect, store, or use to build emails or confirmation pages for the user. If you don’t want to do that yourself, it will also contain the URL to our confirmation page in the url attribute. If you pass the "send_mail": true option, pretix will also send order confirmations for you.

Handling payments yourself

If you want to handle payments in your application, you can either just create the orders with status “paid” or you can create them in “pending” state (the default) and later confirm the payment. We strongly advise to use the payment provider "manual" in this case to avoid interference with payment code with pretix.

However, it is often unfeasible to implement the payment process yourself, and it also requires you to give up a lot of pretix functionality, such as automatic refunds. Therefore, it is also possible to utilize pretix’ native payment process even in this case:

Using pretix payment providers

If you passed a payment_provider during order creation above, pretix will have created a payment object with state created that you can see in the returned order object. This payment object will have an attribute payment_url that you can use to let the user pay. For example, you could link or redirect to this page.

If you want the user to return to your application after the payment is complete, you can pass a query parameter return_url. To prepare your event for this, open your event in the pretix backend and go to “Settings”, then “Plugins”. Enable the plugin “Redirection from order page”. Then, go to the new page “Settings”, then “Redirection”. Enter the base URL of your web application. This will allow you to redirect to pages under this base URL later on. For example, if you want users to be redirected to https://example.org/order/return?tx_id=1234, you could now either enter https://example.org or https://example.org/order/.

The user will be redirected back to your page instead of pretix’ order confirmation page after the payment, regardless of whether it was successful or not. Make sure you use our API to check if the payment actually worked! Your final URL could look like this:

https://test.pretix.eu/democon/3vjrh/order/NSLEZ/ujbrnsjzbq4dzhck/pay/123/?return_url=https%3A%2F%2Fexample.org%2Forder%2Freturn%3Ftx_id%3D1234

You can also embed this page in an <iframe> instead. Note, however, that this causes problems with some payment methods such as PayPal which do not allow being opened in an iframe. pretix can partly work around these issues by opening a new window, but will only to so if you also append an iframe=1 parameter to the URL:

https://test.pretix.eu/democon/3vjrh/order/NSLEZ/ujbrnsjzbq4dzhck/pay/123/?return_url=https%3A%2F%2Fexample.org%2Forder%2Freturn%3Ftx_id%3D1234&iframe=1

If you did not pass a payment method since you want us to ask the user which payment method they want to use, you need to construct the URL from the url attribute of the order and the sub-path pay/change`. For example, you would end up with the following URL:

https://test.pretix.eu/democon/3vjrh/order/NSLEZ/ujbrnsjzbq4dzhck/pay/change

Of course, you can also use the iframe and return_url parameters here.

Optional: Cart reservations

Creating orders is an atomic operation: The order is either created as a whole or not at all. However, pretix’ built-in checkout automatically reserves tickets in a user’s cart for a configurable amount of time to ensure users will actually get their tickets once they started entering all their details. If you want a similar behavior in your application, you need to create Cart positions through the API.

When creating your order, you can pass a consume_carts parameter with the cart ID(s) of your user. This way, the quota reserved by the cart will be credited towards the order and the carts will be destroyed if (and only if) the order creation succeeds.

Cart creation is currently even more limited than the order creation endpoints, as cart creation currently does not support vouchers or automatic price calculation. If you require these features, please get in touch with us.