Set Variable chaining for JSON construction

Beginner

Build complex JSON payloads incrementally using chained Set Variable steps and FileMaker's JSON functions.

What you'll learn

How to initialize an empty JSON object in a variable
How to add keys with JSONSetElement one step at a time
How to build a JSON array with JSONSetElement and numeric indexes
How to nest JSON objects within a parent object
How to format multi-line JSONSetElement calls for readability

FileMaker's JSON functions (JSONSetElement, JSONGetElement, JSONDeleteElement, JSONListKeys) let you build structured data entirely within variables. Rather than concatenating strings manually, you use JSONSetElement to add keys to an accumulating JSON object, producing valid JSON that is ready for Insert from URL, Perform Script parameters, or Exit Script results.

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Build a flat JSON object incrementally

Start with an empty object "{}". Each JSONSetElement call takes the current variable, adds a key, and returns the updated JSON. Assign the result back to the same variable. The third argument specifies the value type: JSONString, JSONNumber, JSONBoolean, JSONArray, or JSONObject.

FileMaker Script

Set Variable [ $payload ; Value: "{}" ]
Set Variable [ $payload ; Value: JSONSetElement ( $payload ; "name" ; Contacts::FullName ; JSONString ) ]
Set Variable [ $payload ; Value: JSONSetElement ( $payload ; "email" ; Contacts::Email ; JSONString ) ]
Set Variable [ $payload ; Value: JSONSetElement ( $payload ; "accountID" ; Contacts::AccountID ; JSONNumber ) ]
Set Variable [ $payload ; Value: JSONSetElement ( $payload ; "active" ; 1 ; JSONBoolean ) ]

# $payload is now:
# {"name":"Jane Smith","email":"jane@example.com","accountID":1042,"active":true}

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