Hi Filipa,
How you did the work around ? in the onBeforeRequest?

Hi @Filipa Matos ,

This is a known and expected limitation in OutSystems when exposing REST APIs. OutSystems does not bind REST input parameters whose names contain special characters like [ and ], even though they are correctly URL‑encoded and visible in GetRawURL.

Root cause:

OutSystems REST input binding only supports parameter names that are valid OutSystems identifiers, which means:

• Allowed parameter naming:
  • EmployeeCode
  • employee_code
  • employee.code
• Not supported naming: 
  • Employee[Code]
  • Employee(Code)
  • Employee-Code
  • Any name requiring URL‑encoding

Even when encoded (%5B, %5D), OutSystems does not match them to inputs. Since OutSystems does not allow special characters in variable naming.

GetRawUrl still works because it

• Reads the raw HTTP request
• Bypasses OutSystems’ parameter binding
• Shows the data exactly as received

But,

• Binding happens before the logic runs
• By the time inputs are populated, the parameter is already discarded

Solution:

Option 1:  Change the parameter name (best practice)

• Instead of Employee[Code], Use EmployeeCode or: Employee_Code

Option 2: Pass complex parameters in the body if you need structured data:
    {  
        "Employee": 
         {    
             "Code": "ABC"
          }
    }

Option 3: Manually parse the query string 

As a workaround only: 

• Use GetRawURL() 
• Extract query string 
• Parse Employee%5BCode%5D yourself

Hope this helps,

Cheers,

Saugat