Find and filter data in Postman Flows

Frequently, the need arises to check if information in a Flow has a certain value. Depending on how structured the information being returned from an API is, there are several different ways to solve for this using FQL.

Contains

contains is the most straightforward way to check if some quoted information contains a word or pattern (regex). Since contains returns either true or false, it's often used with an If block. The example below illustrates how information is only passed through the If block when the input contains the expected value.

Filter

filter is for when there is a list of elements but only some are needed for the next block of the Flow. To use filter, the function looks like $filter(list name,fn($v,$i,$a) { filter condition }) where $v is the values in the list, $i is the index (zeroth item, first item, second item, and so on), and $a is the entire list. Generally $v is the important value for filtering and the only one actually required to be used. In the example below, there is a list of companies, but only enabled companies are needed for the rest of the Flow.

Count

count returns the number of items in a list. This is commonly used because APIs will often return a list of items, especially when using APIs that are searching for something (like an email or something not unique). When this happens, there will need to be a check in the Flow to see if only a single record is returned by the API or if there is a list and further filtering is required. Another case where this function is useful is in generating a random result from a list. In the below example, the recipe API returns a list of recipes and the Flow selects a random one from the list.

Distinct

distinct returns only the unique items in a list. Sometimes, there are duplicate entries in a list of results (maybe someone signed up with two different emails) and the Flow needs to filter them out.