# Custom Function pass a dynamic variable to cal.com

**URL:** <https://community.retellai.com/t/custom-function-pass-a-dynamic-variable-to-cal-com/994>\
**Category:** Support Help\
**Tags:** general\
**Created:** [March 7, 2026, 12:23am UTC](https://community.retellai.com/t/custom-function-pass-a-dynamic-variable-to-cal-com/994 "2026-03-07T00:23:42Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![matthewkwok](https://yyz2.discourse-cdn.com/flex008/user_avatar/community.retellai.com/matthewkwok/32/992_2.png) [@matthewkwok](https://community.retellai.com/u/matthewkwok)\
**Post date:** [March 7, 2026, 12:23am UTC](https://community.retellai.com/t/custom-function-pass-a-dynamic-variable-to-cal-com/994/1 "2026-03-07T00:23:42Z")

</div>

Does anyone know how to setup a custom function for booking a specific cal dot comevent type and also pass along to cal dot com the reason/context for setting up the call that I conveniently saved as a dynamic variable called {{clientInquiry}}. The mapping to the cal dot com meeting is to fill in the {{notes}} header.

The below is the error. You can see that the {{clientInquiry}} is passing into the {{notes}} header.

“Axios Error: error code: ERR\_BAD\_REQUEST, error message: Request failed with status code 400 response status: 400 response data: [{“status”:“1”,“timestamp”:“2”,“path”:“3”,“error”:“4”},“error”,“2026-03-07T00:12:02.894Z”,“/v2/bookings?eventTypeId=4768921&notes=I%20just%20need%20help%20with%20immigration%20visa%20to%20Canada”,{“code”:“5”,“message”:“6”,“details”:“7”},“BadRequestException”,"call property is wrong,property call should not exist , name property is wrong,property name should not exist , args property is wrong,property args should not exist , start property is wrong,start must be a valid ISO 8601 date string , attendee property is wrong,attendee should not be null or undefined , eventTypeId or eventTypeSlug + username property is wrong,Either eventTypeId or eventTypeSlug + username or eventTypeSlug + teamSlug must be provided ",{“message”:“6”,“error”:“8”,“statusCode”:400},“Bad Request”]”

This is my JSON schema:

{  
“type”: “object”,  
“required”: [  
“start”,  
“attendee”  
],  
“properties”: {  
“start”: {  
“type”: “string”,  
“description”: “ISO 8601 date string for appointment start time”  
},  
“eventTypeId”: {  
“type”: “number”,  
“const”: 4768921  
},  
“attendee”: {  
“type”: “object”,  
“properties”: {  
“name”: {  
“type”: “string”,  
“description”: “{{clientFullName}}”  
},  
“email”: {  
“type”: “string”,  
“description”: “{{clientEmailAddress}}”  
}  
}  
}  
}  
}

---

<div class="post-metadata">

**Author:** ![dev.developerforge](https://yyz2.discourse-cdn.com/flex008/user_avatar/community.retellai.com/dev.developerforge/32/1012_2.png) [@dev.developerforge](https://community.retellai.com/u/dev.developerforge)\
**Post date:** [March 9, 2026, 7:33pm UTC](https://community.retellai.com/t/custom-function-pass-a-dynamic-variable-to-cal-com/994/2 "2026-03-09T19:33:27Z")

</div>

From what I know, you first have to ensure the fields exist in cal dot com Event settings (under advanced settings) and then use the proper json schema to book i.e.  
{  
“start”: “{{appointmentStart}}”, // this has to be in ISO format like so: 2026-03-10T14:00:00Z  
“eventTypeId”: [event type id] ,  
“attendee”: {  
“name”: “{{clientFullName}}”,  
“email”: “{{clientEmailAddress}}”  
},  
“notes”: “{{clientInquiry}}”  
}

You can either have these variables in notes section of your cal booking or in individual fields. Fields like name, phone, email and notes are predefined.

---

<div class="post-metadata">

**Author:** ![support2](https://yyz2.discourse-cdn.com/flex008/user_avatar/community.retellai.com/support2/32/15_2.png) [@support2](https://community.retellai.com/u/support2)\
**Post date:** [March 9, 2026, 10:37pm UTC](https://community.retellai.com/t/custom-function-pass-a-dynamic-variable-to-cal-com/994/3 "2026-03-09T22:37:12Z")

</div>

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