# Changing assertions for API monitoring checks > API check assertions on JSON bodies will apply to *each element* in a response array to use JSON path expressions to check all array values. Source: https://www.checklyhq.com/blog/we-are-making-a-change-to-assertions/ --- [Blog](https://www.checklyhq.com/blog/) / [Announcements](https://www.checklyhq.com/blog/tag/announcements/) # Heads up: we are making a change to assertions for API checks [Tim Nolet](https://www.checklyhq.com/blog/author/tim-nolet/) October 21, 2020 · Updated January 12, 2024 _Update: this has been released as per 13:00 CET on 11 November. We delayed it a week due to some rescheduling of other items on our roadmap._ This post is to give you a heads up of a change we will release on Tuesday November 3rd that could impact a tiny percentage of your [Checkly API monitoring](https://www.checklyhq.com/blog/what-is-api-monitoring/). Take 5 minutes and read this through. There is a (very) large chance this will not impact you, but we are being extra careful here. ## What is changing? In a nutshell: > _API check assertions on JSON bodies will apply to *each element* in a response array instead of to the array as a whole. This enables using JSON path expressions to check all array values._ - If you are not asserting JSON bodies, please skip all of this and enjoy your day. - If you are confused, let's look at some examples... ## This is how it will work Just to be 100% clear: this describes the new / upcoming situation. Let's say your API returns a JSON array as a response, i.e. ``` [ { "customerId": 1234, "name": "John Doe" }, { "customerId": 5678, "name": "Kate Doe" } ] ``` You want to make sure that each customer name has the word "Doe" in it. You can now check this with the `$[*]` JSON path operator and a simple `Contains` comparison This will check if each `name` attribute in the array will contain the word "Doe". In this case the assertion will pass ✅ Let's extend the example with the `active` boolean attribute. ``` [ { "customerId":1234, "name":"John Doe", "active":true }, { "customerId":5678, "name":"Kate Doe", "active":false } ] ``` Say we want to assert that every customer in the array is `active` with the following assertion: Again, this will check if each `active` attribute in the array is `true` and will therefore fail ❌ because Kate Doe is not active. ## This will break We've identified one specific corner case that will break under this new regime. Look at the following payload. We've added the `tags` array to each customer. ``` [ { "customerId":1234, "name":"John Doe", "tags": ["one_tag", "another_one"] }, { "customerId":5678, "name":"Kate Doe", "tags": ["i_love_tags"] } ] ``` We want to check if the word "tag" is part of each `tags` array. We use the following assertion: - In the **current / old** situation, this assertion will pass ✅ as JSON path will yield the string `[one_tag, another_one, i_love_tags]` and clearly the word `tag` is in there. Twice even! - In the **upcoming / new**situation, this will fail ❌ as we check each item in this array separately and clearly the word `another_one` does not contain the word `tag`. _If you have such an assertion, I would advise to just remove it now and set a short reminder for yourself to add a similar one after 2 November._ ## This will all not break JSON responses with arrays can already be asserted in many ways using JSON path queries. All of the examples below will not break. The reason is that the JSON path queries below all yield exactly one item from the array. The moment our comparison operator comes into play, we are not "looking at" an array anymore. ### Targeting a specific item by index In the first example below we check if the first item in our result array has a property `title`: \"api In the next example we pick the last item in the array and check if the `customerId` property has the value `123abc`: \"api In this example we pick the item with index value 4. This is the 5th item as array indexes start at 0. We then assert that the `responseTime` property is less than `2000`. \"api ### Targeting the length of an array In the last example we check if the returned array has more than 10 items. \"api ## ​What should I do? - Check if you are using API checks that assert JSON response arrays "as a whole". - If so, just remove them for now and set a short reminder to add a similar assertions after 2 November. In the worst case, you will be alerted of a failing check on 2 November and the result will clearly state what is wrong. For any follow up questions, don't hesitate to reach out to support using the chat bubble! [Tim Nolet Chief Evangelist](https://www.checklyhq.com/blog/author/tim-nolet/) In This Article - What is changing? - This is how it will work - This will break - This will all not break - ​What should I do? Share on social ## Related Articles [User-scoped API Keys November 17, 2021](https://www.checklyhq.com/blog/user-scoped-api-keys/)[How low-level API calls can stabilize your end-to-end tests June 16, 2022](https://www.checklyhq.com/blog/how-low-level-api-calls-stabilize-your-end-to-end-tests/)[What is API Monitoring? 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