06_getSingleBooking.md

GET /booking/{id}

In this example we will be getting the data for a single booking from the API. We will explore the endpoint using Request Headers and also taking a basic look at the Pre-request Scripts feature to make our request a little bit more dynamic.

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In a previous example we made a basic GET request to the /booking endpoint and this returned the following response.

So for this example, we will be taking those bookingid values seen in the response above and using the /booking/{id} endpoint to return data relating to that Id. Along the way we will be using several different Postman features to interact with the endpoint and change the type of data returned using a specific Request Header. As this is a new endpoint, let's look at the documentation to see what is on offer to us.

The endpoint takes an id parameter value in the request, we know from the /booking request that we made, that this is a number but in the documentation it states that this is a string value and not an integer so I'm instantly thinking of different ways to manipulate that value to expose potential issues.

Get information about a single booking

We have our list of available id's from the previous request, we're going to use the first id in the request to the /booking/{id} endpoint and explore the data returned in the response.

In the clip below, I am sending the following request {{baseURL}}/booking/10 - The baseURL value is set in the Restful_Booker_Environment file.

The request gave us the following response data back in a JSON format. As you can see, some of the values in the response relate to the query parameters used to filter the response of the /booking endpoint. Hopefully, now you can see why the response data was changing each time you made a request.

{
    "firstname": "Sally",
    "lastname": "Jackson",
    "totalprice": 898,
    "depositpaid": true,
    "bookingdates": {
        "checkin": "2016-10-25",
        "checkout": "2018-02-27"
    },
    "additionalneeds": "Breakfast"
}

The nice thing about Postman is that it displays the response data in Pretty print by default and this is awesome, for me, it makes it so much easier to read. If you would like to see the response displayed a different way, Postman has a couple of options for you - Raw and Preview. Switch between this options to see the data in these display modes. The clip below shows how this looks in the application for the response data above.

Using Request Headers

In the last example we looked at using Preset Headers but we didn't actually use them to make a request to the Restful-Booker API. Fear not, that's about to change. We are going to be using the Accept header to change to way that the response data is returned - There are two different response data types for this endpoint application/json and application/xml. The default seems to be application/json, if a header is not supplied in the request.

Adding a new header is straight forward enough:

• In the Request Builder view, select the Headers tab
• Add Accept in the Key text field
• Add application/xml to the Value field next to the key

You will notice as you type into the fields, there is a handy auto-complete feature, this displays several options available to you.

With the application/xml header set, you can see that the following response is sent back:

<?xml version='1.0'?>
<booking>
    <firstname>Sally</firstname>
    <lastname>Jackson</lastname>
    <totalprice>898</totalprice>
    <depositpaid>true</depositpaid>
    <bookingdates>
        <checkin>2016-10-25</checkin>
        <checkout>2018-02-27</checkout>
    </bookingdates>
    <additionalneeds>Breakfast</additionalneeds>
</booking>

A couple of quick things that I have noticed when using the application/xml header in the request, Postman tries to automatically match the response data type. It looks like that the API is returning, what looks to me like valid xml, but the validation has failed for some reason...This is a perfect opportunity to explore this further.

Looking at the Response Headers - This is an area we will cover in more detail soon, we can see that the response Content-Type is text/html...There is clearly something strange happening here, it would need more time to dig into this issue more by either setting up a proxy tool like Fiddler or even better, pairing up with the developer to investigate the issue together. I'm not going to go down that route now as it will shift the focus away from Postman.

Before moving on to do a quick introduction to the Pre-request Script feature, I'm always looking for ways to bend the rules that I've seen explicitly written in some documentation. As Testers, we always seem to be on the look out for What if.. scenarios, Request Headers are absolutely something that can be explored. So what do we know? We have been told that their are two types of headers that can be used but we know that there are so many more available...What if...I used a different one?!

That's an interesting response back when using a different Accept header - 418 I'm a teapot :)

Dynamic Requests

"Pre-request scripts are snippets of code associated with a collection request that are executed before the request is sent. This is perfect for use-cases like including the timestamp in the request headers or sending a random alphanumeric string in the URL parameters."

This is probably my favourite Postman feature, I'm going to be spending a whole bunch of time creating future examples for this feature because it can be used in so many useful ways. For this introduction, I'm going to show you how we can use it to make our requests to the /booking/{id} endpoint slightly more dynamic. The default total number of booking id's returned from the /booking endpoint is normally 10. What we are going to do is use one of the built in Lodash functions to create a random number between 1 and 10, then use that value in our request. I'm going to be covering the built in modules it a later example so don't worry if this is a little bit confusing. :)

_.random(1,10)

To show you what's going on with this _.random() feature, I've logged out the created value, in the Postman Console. As you can see, the numbers returned are all between 1 and 10. The numbers that you pass the _.random function are the lower and upper ranges so this could be used to create any range that you need. A really handy feature!! :)

The Pre-request Script feature is basically just a little JavaScript IDE...ish, the code above is simple and it just generates a random number. There are lots of handy JavaScript tutorials where you can learn the basics on the W3schools website. We have the code to create the value so how can we use this in a request?

Postman has a bunch of built-in code Snippets that you can use - We are going to be using the Set an environment variable snippet. This will place a key/value pair of data into our Restful_Booker_Environment file. The Snippets are listed down the right hand side of the request data builder.

From the clip above you can see that we have selected the Set an environment variable snippet and this has been added to our pre-request script window. We then give our new variable a name as this is the key that we will be referencing in our request, I've called mine booking_id. Finally, the JavaScript code to create the random number is added as the value. Simple right?! Now let's start using it in our request.

In the request URL, we can use the {{booking_id}} syntax to set the variable value and send our request to the API endpoint. You can see that the variable is set for the first time (It changes colour from red to orange), just before the request to the API is sent.

That's the end of this example. We have learnt how to use request headers to change the data in the response and we have also taken a super quick look at pre-request scripts. More to come on those very soon, It's a great feature of Postman and I want to write a few single examples on that feature to do it justice.

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