How to count members with jsonpath?

How to count members with JSONPath?

📝 Hey there, tech enthusiasts! Are you wondering how to count the number of members using JSONPath? Look no further! In this guide, we'll tackle this common question and provide you with easy solutions. Let's dive in!

The Problem: Counting Members with JSONPath

😕 So, you're testing a controller that generates JSON using Spring MVC test. You want to ensure that no unexpected members are present in the generated JSON. In other words, you want to count the number of members using JSONPath.

👉 Here's an example of the JSON generated by the controller:

{"foo": "oof", "bar": "rab"}

You want to ensure that only the members "foo" and "bar" are present in the JSON and that there are no additional members.

The Solution: Using JSONPath to Count Members

✔️ Fortunately, you can achieve this using JSONPath. JSONPath is a powerful tool for querying and manipulating JSON data structures. Here's how you can count the members using JSONPath:

1. In your test setup, perform the JSONPath assertion after verifying other expectations, like the values of "foo" and "bar".

   standaloneSetup(new FooController(fooService)).build() .perform(get("/something").accept(MediaType.APPLICATION_JSON)) .andExpect(status().isOk()) .andExpect(jsonPath("$.foo").value("oof")) .andExpect(jsonPath("$.bar").value("rab")) .andExpect(jsonPath("$.length()").value(2)); // Count members using $.length()

   In the last line of code above, $.length() is used to count the number of members in the JSON structure. The assertion .value(2) ensures that the count is equal to 2 (representing "foo" and "bar").

2. If you want to assert that there are no additional members, you can modify the assertion as follows:

   .andExpect(jsonPath("$.*").value(hasSize(2))); // Assert that there are exactly 2 members

   Here, $. is used to match all members in the JSON structure. The hasSize(2) assertion checks that the size of the matched members is equal to 2.

Alternatives and Further Reading

🔎 JSONPath is a versatile tool that allows you to perform various queries on JSON data. If you're interested in exploring more advanced features or using JSONPath for other purposes, here are a few resources to check out:

• JSONPath Online Evaluator - A handy online tool to experiment with JSONPath expressions.

• Jayway JSONPath GitHub Repository - The official repository for the Jayway JSONPath library, which provides JSONPath support for Java.

💡 Remember, understanding how to count members with JSONPath can be immensely helpful in testing and ensuring the correctness of your JSON structures!

Conclusion and Call-to-Action

🎉 Congratulations! Now you know how to count members using JSONPath. You can easily verify the presence or absence of certain members in your JSON structures, ensuring their correctness and preventing unexpected surprises.

👉 Do you have any other JSONPath-related questions or exciting use cases? Share them with us in the comments below! Let's continue the conversation and explore the wonders of JSONPath together.

📢 Don't forget to share this blog post with your fellow tech enthusiasts who might benefit from this knowledge. Happy coding! 💻🚀