How to pass a JSON parameter to a FileMaker script

Intermediate

Script parameters are a single text value. Learn why JSON is the right way to pass multiple values, and how to read them back inside a script.

What you'll learn

Why FileMaker scripts only have one parameter, and how to work with that
How to pass multiple values using a JSON object as the parameter
How to read individual values inside the script with JSONGetElement

Every FileMaker script receives exactly one parameter — a text string. When you need to pass more than one value, the pattern is to encode them as a JSON object and decode them inside the script using JSONGetElement.

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Pass a JSON object as the script parameter

When calling a script, build a JSON object using JSONSetElement and pass it as the parameter. Each key is a named argument.

FileMaker Script

# Build the parameter
Set Variable [ $param ; Value:
  JSONSetElement ( "{}" ;
    [ "customerId" ; Customers::id ; JSONNumber ] ;
    [ "mode"       ; "edit"         ; JSONString ]
  )
]

Perform Script [ "Update Customer" ; Parameter: $param ]

All Scripting lessons FileMaker script error handling with Set Error Capture