Postman REST API Client: Designing, Developing & Testing APIs

on API, postman, REST API, Tutorials • November 3rd, 2021 • Write for Hevo

Postman is an API advancement environment that is used to test APIs, make robotized tests, get data or responses from your requests, and lots more. This is one of the most scalable API testing tools that can be easily inserted with the CI/CD pipeline. Using Postman REST API Client, you can make your process of creating, sharing, testing, and documenting APIs easier.

In this blog, you will get introduced to the Postman REST Client and get to know the reason behind its success. You will understand the installation and working of the Postman REST Client. You will be exposed to GET and POST requests in the Postman REST Client.

Table of contents

What is Postman REST API?

Postman REST Client- Postman logo
Image Source: Postman

Postman is an Application Programming Interface (API) development tool that helps you build, test, and modify APIs. Postman can also be regarded as a collaboration platform that aids API development and helps in the creation of better and faster APIs by simplifying each step in the process of building an APIs therefore, allowing streamlined collaborative efforts.

Postman boasts of almost all functional tools needed by developers as they are encapsulated on the platform thereby making it a popular API platform used by over 5 million developers monthly. It can handle various types of HTTP requests ranging from GET, POST, PUT, to PATCH, converting the API to code for other languages like JavaScript, Python, etc. Postman can also save your environments for later use.

Some of its key features are:

  • Seamless automated testing.
  • Collaboration features for effortless sharing and management.
  • Supports Swagger and RAML (RESTful API Modeling Language) formats.
  • Offers powerful visualization compatibility.
  • Supports multiple protocols, manages cookies, and manages certificates.

Why Postman REST API is preferred?

Postman REST Client software is gaining attention nowadays because of its exciting features. The main reason for choosing Postman REST Client is its Accessibility. Postman REST Client serves a lot of purposes like sending requests and inspecting responses. Using Postman REST Client, you can easily debug REST APIs. Postman REST API comes with a very easy-to-use user interface with which you just need Postman installed on your PC. You can access your files anytime and anywhere, which makes the entire process easier.

Postman REST API software also provides an option to create collections for their Postman REST Client API calls. These collections will also have subfolders and can make multiple requests.

Using Postman REST Client, you can easily import and export files. You can have a direct link to share files with ease. Postman REST Client provides you with multiple environments. These multiple environments will reduce the number of repetitions of tests for the same collection for various environments. With Postman REST Client software, you can create test checkpoints. These test checkpoints verifies each successful HTTP response status and updates the Postman API calls. This ensures entire test coverage.

Postman REST Client software has got the automatic testing option with Collection Runner or Newman. With this, you can run multiple iterations parallely and avoid repetitive testing. Postman REST Client is really easy to debug and retrieve. Postman REST API also gives a continuous integration option.

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Postman Installation

Postman is an Open Source tool, and hence can be easily downloaded. Here are the steps in Postman Installation.

Step 1: Download your device’s compatible version of Postman from this link. Click Download to get the setup downloaded.

Postman REST Client- Postman download window
Image Source: guru99

Step 2:  After running the .exe file downloaded. Now signup for aa Postman Account.

Postman REST Client- Postman sign up
Image Source: guru99

Step 3: Now setup your workspace tools by selecting it. Just click and save your preferences.

Postman REST Client- Postman set up
Image Source: guru99

Step 4: It is all set now! Your Startup Screen will look like this.

Postman REST Client- Getting started with Postman
Image Source: guru99

How to use Postman to execute APIs?

Here is a detailed view of all the features and processes of Postman REST API. A Postman Workspace picture is shown below.

Postman REST Client- API Execution
Image Source: guru99
  1. New – Using this you can create new requests, collections or environments.
  2. Import – You can import a collection or environment with this. You also have options such as import from file, folder, link or paste raw text.
  3. Runner – You can run automation tests using the Collection Runner.
  4. Open New – Using this you can open a new tab, Postman Window or Runner Window.
  5. My Workspace – With this you can create a new workspace individually or as a team.
  6. Invite – This is used to invite team members for a workspace collaboration.
  7. History – You can keep a track of all your past requests in this History.
  8. Collections – This is used to organize all your test suite using collections.
  9. Request tab – This tab will show the title of the request that you are currently working on. The default title is “Untitled Request”.
  10. HTTP Request – This dropdown has different HTTP requests like GET, POST, COPY, DELETE, etc. In Postman REST API testing, GET and POST are frequently used.
  11. Request URL – This is also named as an endpoint. Using this you can identify the link to you API’s communication.
  12. Save – You have to save all the new changes when made. Else they will be lost or overwritten.
  13. Params – You have to enter all the parameters requireed for a request like key values.
  14. Authorization – Authorization is required for safe access. Authorization will be in the form of a username and password, bearer token, etc.
  15. Headers – Based on your organisation’s requirement, you can choose headers such as content type JSON.
  16. Body – You can customize the request details here.
  17. Pre-request Script – These scripts are used to verify if the test are running in the right environment. This is executed before the actual request.
  18. Tests – You have to execute these scripts during the request. All these are used as checkpoints too verify the response status, data retrieved and other tests.

Working with Postman REST Client

Postman REST Client: Send Requests and View Responses

Postman REST API is used to create complex requests, pick up the pace during query execution, and verify responses. You can create and execute queries using Postman REST Client.

Postman REST Client- view responses
Image Source: Postman

Create complex requests

Using Postman REST Client, you can send all the types of requests. You can define and save customized requests and send them using these body types.

  • URL-encoded: This is the default type used to send simple text data.
  • Multipart/form-data: This is used to send data in large quantities of non-ASCII text or binary data.
  • Raw body editing: This is used to send data when encoding is not required.
  • Binary data: This is used to send other file types like images, audio, or video.

Fast execution

Postman REST Client is one of the best alternatives for manual call creation and sending them over the command line. To use Postman REST Client for fast execution, you can directly import a collection. You can also generate from an API schema in the RAML, WADL, OpenAPI, or GraphQL format or a data file with the cURL commands.

Verify responses

Using Postman REST Client, you can inspect responses. You can view the status code, response time, and response size easily using Postman REST Client. Postman has an automatic language detection option in it. You can link and highlight syntaxes, search, and format texts easily using Postman REST Client.

Postman REST Client: Visualize Your Data

Postman REST Client has hot a Visualizer that can easily convert your API data into graphs and plots.

Postman REST Client- visualize data
Image Source: Postman

Using Postman Visualizer you can avail the following benefits:

  • Build your own visualization style: You can make use of HTML5, JavaScript, and CSS to build your own visualization pattern. You can also bring in the existing charting and graphing libraries to make meaningful visualizations.
  • Make use of the powerful inbuilt visualizations: Instead of making use of the API JSON or XML responses, you can go one step ahead. If you are an API consumer, you can get more from the data you have in hand. Postman REST Client provides you with inbuilt charts and graphs for visualizations.
  • Share these visualizations with your teams: You can share your visualizations easily in a single click with your fellow team using Postman collections.

Postman REST Client: Built-In Support for Variables

Using Postman REST Client, you can reuse values in more than one place with variables. By this, you can retain your code and requests DRY.

Postman REST Client- inbuilt variable support
Image Source: Postman
  • Create variables in multiple scopes: Using Postman REST Client, you can store the values at the global level, environment level, and also collection level. You have the liberty to add variables to the URL, URL parameters, headers, authorization, request body, and header in the Postman REST Client directly.
  • Fast diversified requests: You can use these environments to move between various setups without altering your requests, All you need to do is to choose the correct environment to update all your variables.
  • Safeguard information with session variables: You can manage all your high-priority sensitive data like API keys by storing them in session variables which will stay local in your own machine. This will never sync with your fellow teammates.

Postman REST Client: Manage Authentication

Postman REST Client provides you with access to the APIs even without the authentication protocols.

Postman REST Client- Authentication
Image Source: Postman
  • Handle multiple protocols efficiently: Postman REST Client comes with inbuilt support authentication protocols like OAuth 2.0, AWS Signature, Hawk Authentication, and more.
  • Manage cookies: Postman REST Client manages cookies very effectively. It gets the cookies that are back from the server while making a request. It saves these cookies and later use them in other requests. Postman REST Client will also help you to add cookies and customize your domain.
  • Manage Certificates: You can manage your certificates using Postman REST Client. In this, you have the option to view see and fix the SSL certificates according to the domain need. When you add a client certificate, it will eventually reach with a request to that domain over HTTP. The certificates that Postman REST Client generally supports are SSL certificate validation, the Custom root CA Certificate support, and Client certificate support.

Working with GET Requests

You can use GET requests to retrieve data from the specified URL. No change will be made to the endpoint. For this example, we’ll use this URL:

https://jsonplaceholder.typicode.com/users

Here are the steps that you must follow:

  1. Set your HTTP request to GET.
  2. In the request URL field, enter the link.
  3. Now, Click Send.
  4. You will see 200 OK Message
  5. There should be 10 user results in the body which indicates that your test has run successfully.
Postman REST Client- GET requests
Image Source: guru99

Working with POST Requests

Post requests does data manipulation with the user by adding data to the endpoint.

Step 1: Create a new request by selecting the new tab.

Postman REST Client- POST request
Image Source: guru99

Step 2: Now do these modifications in the new tab

  1. Set your HTTP request to POST.
  2. Enter the same link in request url: https://jsonplaceholder.typicode.com/users
  3. Now switch to the Body tab
Postman REST Client- making modifications in GET request
Image Source: guru99

Step 3: After this, select raw and JSON in Body.

Postman REST Client- choosing JSON in body
Image Source: guru99

Step 4: Copy and paste only one user result from the previous get request like below. Now alter the id to 11 and name to any desired name. And also change the address details.

Postman REST Client-GET request
Image Source: guru99
Postman REST Client- GET request
Image Source: guru99

Step 5: Next select Send. Then Status:201 Created will be displayed in the bottom. Now you can see that your data posted in shown in the body.

Postman REST Client- GET successful
Image Source: guru99

Postman REST Client features: Postman Addon

Postman REST Client is one of the most powerful tools for API exploration and development. Apart from the features discussed already, here are some additional features of the Postman REST Client.

  • Track request history: Postman REST Client helps you to track all your request history. All the requests sent are stored and can be viewed in the “History” tab. You need not waste time by building everything from scratch.
  • Generate code snippets: You can generate your request code snippets using different frameworks and languages using Postman REST Client. You can also use the same request from your own application.
  • Write tests in Postman Sandbox: You can test your scripts and add dynamic behavior to requests and collections. You can also write test suites, build requests that contain dynamic parameters, pass data between requests, and more.

Conclusion

From this blog, you have learnt about the Postman REST Client and got to know the reason behind its success. You would have understood the installation and working of the Postman REST Client. Hevo’s native REST API connector can help connect with a variety of non-native/custom sources into your Data Warehouse to be visualized in a BI tool.

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