When using JMESPath for transforming JSON, a basic concept that is used a lot, is the notion of a key\/value pair. We use key\/value pairs to order our data in both JMESPath and JSON. <\/p>\n\n\n\n
Let’s take a look at a simple example of how it looks in JSON.<\/p>\n\n\n\n
{\n \"name\": \"John Doe\"\n}<\/code><\/pre>\n\n\n\nHere we have two strings being separated with a :<\/code>. The string on the left side \"name\"<\/code> is the key which, when referenced to it, will return the value string \"John Doe\"<\/code>. This is a simple example on a key\/value pair in JSON, where the value is a string. It should be noted that the key should always be a string, but the value can be of any allowed JSON data type<\/a>. <\/p>\n\n\n\nWhen transforming the JSON with JMESPath in Documotor, we follow the same structure with the key\/value pair, where we define new keys based on the contents of the JSON data. However, you can also create key\/value pairs in JMESPath with customized data. Let’s look at an example with both JSON and JMESPath. <\/p>\n\n\n\n
Assume we have the following JSON sample data. <\/p>\n\n\n\n
{\n \"firstName\": \"John\",\n \"lastName\": \"Doe\",\n \"age\": 34\n}<\/code><\/pre>\n\n\n\nWith JMESPath, we can define a new key\/value pair. See below how we transform the sample data. <\/p>\n\n\n\n
{\n name: join(' ', [firstName, lastName]),\n age: age\n}<\/code><\/pre>\n\n\n\nNote that we in JMESPath do not have to surround the key with \"<\/code> as we have to do with the JSON key. In the value, instead of writing a string, we use the join<\/code> function to concatenate the two values from the JSON sample data. We also do not have to surround the JSON keys we are referencing to in the function with \"<\/code> either. When defining a JMESPath transformation, it is only the data defined in this transformation that is passed forward. If you look at line 3 of the JMESPath transformation, you can see that we define a key\/pair value that simply repeats the key from the JSON sample data in order to make sure the data is passed on to the result data. In the age: age<\/code> key\/value pair, the value is referring to our JSON sample data. See below the result from the above transformation. <\/p>\n\n\n\n{\n \"name\": \"John Doe\",\n \"age\": 34\n}<\/code><\/pre>\n\n\n\n