Manipulating Multi-Module Lookup Field using Zoho CRM APIs

Manipulating Multi-Module Lookup Field using Zoho CRM APIs

Hello everyone!

Welcome back to another week of Kaizen.
In this post, we explore the Multi-Module Lookup (MML) field in the Appointments module of Zoho CRM. You learn what an MML field is, how it works, and how to use it with Zoho CRM APIs.



Table of Contents:

  • What is a Multi-Module Lookup (MML) Field in Zoho CRM?
  • Use Cases for MML
  • How  the "Appointment For" (MML) field in the "Appointments" module works?
  • Creating a Record in the Appointments Module Using the Insert Records API
  • Retrieving a Record from the Appointments Module Using the Get Records API
  • Multi-module Lookup Using the COQL API
  • Multi-module Lookup Using the Bulk Read API
  • Frequently Asked Questions

What is a Multi-Module Lookup (MML) Field in Zoho CRM?

A Multi-Module Lookup (MML) field in Zoho CRM allows you to create a one-to-one relationship between a record in one module and a record from one of multiple other modules. Unlike a normal lookup field, which references a single module, an MML field can dynamically reference records from multiple modules. 
Without the MML field, users must create multiple lookup fields for each module, which complicates the CRM layout and user experience.

Note:
  • The multi-module lookup (multi_module_lookup) data type was introduced in Zoho CRM API version 3.
  • Currently, the MML field is available as a system-defined field named Appointment For in the Appointments module. 
  • The Appointment For field supports lookups to both Contacts and custom modules.
  • You cannot create a custom MML field in Zoho CRM.


Data Model Representation

MML's Data Model Representation

Use Cases for MML


Zylker Healthcare is a multi-specialty hospital that uses Zoho CRM to maintain its appointment scheduling process. 

In this setup, Zylker maintains two key modules:
  • Contacts module - Stores records of physicians and surgeons, including attending physicians, specialists, and surgeons who diagnose and refer patients.
  • Patients module - A custom module used to maintain records of all patients.

To improve the appointment booking process, Zylker uses the "Appointment For" Multi-Module Lookup (MML) field in the Appointments module. This field lets Zylker manage an appointment with either a Physician/Surgeon or a Patient, eliminating the need for multiple lookup fields.

How  the "Appointment For" (MML) field in the "Appointments" module works?

  • When creating an appointment, the user selects the "Appointment For" field.
  • The field displays records based on the selected module, either the Contacts or  Patients
  • The user selects the appropriate record (Contact or Patients) for the appointment.
  • A related list is automatically created in the selected module (Contact or Patients) as the Open Activities / Closed Activities to display all appointments associated with that record.

Creating a Record in the Appointments module using the Insert Records API

Before creating a record in the Appointments module via the Insert Records API, make sure you know the API names of the system-defined mandatory fields. These fields are required to create an appointment successfully.

System-defined Mandatory Fields:
  • Appointment_For (MML field)
  • Service_Name
  • Appointment_Start_Time
  • Appointment_Name
  • Member
  • Location

The below image shows how these system-defined mandatory fields appear in the Appointments module UI:

System-defined mandatory keys in the Appointments Module in UI view.

API calls you have to make before creating a record:

Before inserting a record into the Appointments module, it is important to know the API names of the fields and their parent modules. 

i. Use the GET - Module Metadata API to know the API name of the module. In our case, the Appointments module.

Request URL : {api-domain}/crm/v8/settings/modules
Request Method : GET

Sample Response :

 
In the API response, search for the module with "module_name": "Appointments" and check the value of the "api_name" key to get the API name of the module. This is the name you will use in all related API calls.

ii. Use the GET - Fields Metadata API and get fields metadata for the Appointments module. Here, you can find the API names of the mandatory fields along with other fields present in the Appointments module. 

Below is the API call & response for the multi-module lookup field along with other mandatory fields.

Request URL : {api-domain}/crm/v8/settings/fields?module=Appointments__s
Request Method : GET

Sample Response :


Note: The above image highlights only the key properties of the Multi-Module Lookup (MML) field from the field metadata response. The complete API response contains additional properties not shown here.

In the response:
  • The multi-module lookup field is identified by the key "data_type" with the value "multi_module_lookup".
  • The associated modules supported by the MML field (e.g., Contacts, Patients) are listed under the "modules" key.
  • Other mandatory fields like Service Name, Appointment Name, and Appointment Start Time can be identified by "system_mandatory": true.
The keys of the above multi_module_lookup JSON object are explained below:


"multi_module_lookup": {
    "display_label": "Appointments", // Display label of the module where the MML field is used
    "api_name": "Appointments__s", // API name of the Appointments module
    "modules": [ //List of modules associated with the Appointments module. 
        {
            "api_name": "Contacts", //API name of the associated module 
            "module_name": "Contacts", // Display Name of the module 
            "id": "5725767000000002179" //Unique ID of the module
        },
        {
            "api_name": "Patients", //API name of the associated custom module
            "module_name": "Patients", //Display label of the module
            "id": "5725767000006473007" //Unique module ID
        }
    }
]
},

Note: 
  • You cannot add or remove modules from the Multi-Module Lookup (MML) field using APIs. These actions are only available through the Zoho CRM UI.
  • Once a module is disassociated from the MML field, existing records associated with that module will remain in the Appointments module, and you will no longer be able to associate newly created records from the disassociated module using the MML field. 
The remaining system-defined mandatory fields, along with their API names, are listed below.

 

 System-defined Mandatory Field Names

 

 

System-defined Mandatory Field API Names

Service Name

Service_Name

Appointment Start Time

Appointment_Start_Time

Appointment Name

Appointment_Name

Member

Owner

Location

Location


Note: The system-defined mandatory fields can be identified by "system_mandatory": true.

Search the system-defined mandatory field names and get their API names.
With the field API names, use the following request and sample input body to create a record in the Appointments module using the Insert Records API.

Request URL : {{api-domain}}/crm/v8/Appointments__s
Request Method : POST

Request Body :

{
    "data": [
        {
            "Appointment_Name": "General Consultation",
            "Owner": {
                "name": "Patricia Boyle",
                "id": "5725767000000411001",
                "email": "patricia@zohotest.com"
            },
            "Appointment_Start_Time": "2025-04-15T13:00:00-07:00",
            "Appointment_End_Time": "2025-04-15T13:30:00-07:00",
            "Appointment_For": {
                "module": {
                    "api_name": "Contacts",
                    "id": "5725767000000002179"
                },
                "name": "John Doe",
                "id": "5725767000005607020"
            },
            "Service_Name": {
                "name": "General Check-up",
                "id": "5725767000006387029"
            },
            "Location": "Business Address"
        }
    ]
}


Sample Response:


{
    "data": [
        {
            "code": "SUCCESS",
            "details": {
                "Modified_Time": "2025-05-06T20:33:42-07:00",
                "Modified_By": {
                    "name": "Patricia Boyle",
                    "id": "5725767000000411001"
                },
                "Created_Time": "2025-05-06T20:33:42-07:00",
                "id": "5725767000006390001", //Unique ID if the newly created record. Please note that this record ID will be used in the following API get and update operations.
                "Created_By": {
                    "name": "Patricia Boyle",
                    "id": "5725767000000411001"
                }
            },
            "message": "record added",
            "status": "success"
        }
    ]
}



Note:
Only Contacts and custom modules are supported in the Multi-Module Lookup field. If you try to associate a new record with a module that has been removed from the MML field or an unsupported module in the MML field, the following error will be thrown. 


Retrieving a Record from the Appointments Module Using the Get Records API

Request URL : {{api-domain}}/crm/v8/Appointments__s/5725767000006390001
Request Method: GET

Request Response:

{
    "data": [
        {
            "Owner": {
                "name": "Patricia Boyle",
                "id": "5725767000000411001",
                "email": "patricia@zoho.com"
            },
            "$currency_symbol": "$",
            "Address": null,
            "Appointment_Start_Time": "2025-04-15T13:00:00-07:00",
            "Cancellation_Reason": null,
            "$field_states": null,
            "Appointment_For": {
                "module": {
                    "api_name": "Contacts",
                    "id": "5725767000000002179"
                },
                "name": "John Doe",
                "id": "5725767000005607020"
            },
            "Rescheduled_To": null,
            "$sharing_permission": "full_access",
            "Reschedule_Reason": null,
            "Additional_Information": null,
            "Last_Activity_Time": null,
            "Cancelled_Time": null,
            "Cancellation_Note": null,
            "Modified_By": {
                "name": "Patricia Boyle",
                "id": "5725767000000411001",
                "email": "patricia@zoho.com"
            },
            "Reschedule_Count": 0,
            "Rescheduled_By": null,
            "id": "5725767000006390001",
            "Rescheduled_Time": null,
            "Remind_At": null,
            "Appointment_End_Time": "2025-04-15T13:30:00-07:00",
            "Status": "Overdue",
            "Modified_Time": "2025-05-06T20:04:38-07:00",
            "Service_Name": {
                "name": "General Check-up",
                "id": "5725767000006387029"
            },
            "Created_Time": "2025-05-06T20:04:38-07:00",
            "testing": null,
            "Rescheduled_From": null,
            "Cancelled_By": null,
            "$editable": true,
            "Appointment_Name": "General Consultation",
            "Duration": 30,
            "Record_Status__s": "Available",
            "Created_By": {
                "name": "Patricia Boyle",
                "id": "5725767000000411001",
                "email": "patricia@zoho.com"
            },
            "Tag": [],
            "Location": "Business Address",
            "Reschedule_Note": null
        }
    ]
}


Updating MML Field Value Using the Update Records API

Request URL : {{api-domain}}/crm/v8/Appointments__s/5725767000006390001
Request Method: PUT

Request Body:

{
    "data": [
        {
            "Appointment_Start_Time": "2025-04-16T14:00:00-07:00", //Updating the Appointment_Start_Time
            "Appointment_End_Time": "2025-04-16T14:30:00-07:00", //Updating the Appointment_End_Time
            "Appointment_For": {
                "module": {
                    "api_name": "Employees", //Updating a different module
                    "id": "5725767000002161028"
                },
                "name": "Patrica", //A record from the Employees module
                "id": "5725767000006272001" //unique ID of the record
            }
        }
    ]
}


Multi-module Lookup Using the COQL API

Querying Inner Fields of Linked Modules within the MML Field

With the COQL API, you can query inner fields of linked modules within a Multi-Module Lookup (MML) field. This provides deeper insights into related fields data in a module. This query support is available from Zoho CRM API Version 7.

Sample Query:


{
 "select_query": "select 'Appointment_For->Contacts.Lead_Source' from Appointments__s where id is not null"
}

The above query retrieves the Lead Source field from the Contacts module within the Appointment_For MML field. 


Sample Response:



Querying Multi-Module Lookup Module Name

Querying the module name associated with each record in a Multi-Module Lookup (MML) field. This query support is available from Zoho CRM API Version 7.

Sample Query:

{
"select_query": "select Appointment_For.module.api_name, Appointment_For from Appointments__s where id is not null"
}


The Appointment_For.module.api_name returns the module name (e.g., Contacts or Accounts) for each record linked in the Appointment_For MML field.

Sample Response:


Multi-module Lookup Using the Bulk Read API

Bulk Read API allows you to fetch a large set of data i.e., you can fetch a maximum of 2,00,000 records in a single API call. 
Specify the API name of the Appointments module in the module JSON object when making API calls. Refer to the following section for an example.

Request Method : POST

Request Body :

{
    "callback": {
        "method": "post"
    },
    "query": {
        "module": {
            "api_name": "Appointments__s" //API name of the Appointments module
        },
        "file_type": "csv"
    }
}


Note: The Appointment_For field cannot be used in the criteria.

As the API is an asynchronous API, the response will not be available instantly; the bulk read job is scheduled, and the status can be checked. Once the job is completed, you will be notified in the callback URL. The records are available in a downloadable CSV file or ICS file (for events). See the Bulk Read API document to know how to view the status of the scheduled job and download the file, along with more sample requests and responses.

Sample Exported Response 



Frequently Asked Questions

1. Which modules are currently supported in the MML field?

Only Contacts and custom modules can be associated with an MML field.

2. What error is thrown if I try to associate a record with a removed or unsupported module in the MML field?

If you try to associate a record with a removed or unsupported module in an MML field, the system will throw an "INVALID_DATA" error.

3. Is the MML field available for all modules?

No, as of Zoho CRM API Version 8, the MML field is available only as a system-defined field in the Appointments module.

4. How do I get the list of modules associated with an MML field?

You can use the GET - Fields Metadata API for the Appointments module and look for the field with "data_type" : "multi_module_lookup" and check its "modules" JSON array.

5. Can I add or remove modules from a Multi-Module Lookup (MML) field via API?

Adding or removing modules in an MML field is not supported via API. These actions can only be done through the Zoho CRM UI.

6. What happens if I remove a module from an MML field?

If a module is removed from the MML through Zoho CRM UI, it can no longer be associated with new records, but existing records linked to that module will remain unaffected.

7. Is MML field supported in the Bulk Write API?

As of Zoho CRM API Version 8, the MML field is available only in the Appointments module as a system-defined field. The Appointments module is not supported in the Bulk Write API.

8. Is MML field supported in the Search API?

The MML field is not currently supported in the Search API.



We trust that this post meets your needs and is helpful. Let us know your thoughts in the comment section or reach out to us at support@zohocrm.com

Stay tuned for more insights in our upcoming Kaizen posts!

Cheers!!!


Related Readings:


    • Sticky Posts

    • Kaizen #197: Frequently Asked Questions on GraphQL APIs

      🎊 Nearing 200th Kaizen Post – We want to hear from you! Do you have any questions, suggestions, or topics you would like us to cover in future posts? Your insights and suggestions help us shape future content and make this series better for everyone.
    • Kaizen #198: Using Client Script for Custom Validation in Blueprint

      Nearing 200th Kaizen Post – 1 More to the Big Two-Oh-Oh! Do you have any questions, suggestions, or topics you would like us to cover in future posts? Your insights and suggestions help us shape future content and make this series better for everyone.
    • Celebrating 200 posts of Kaizen! Share your ideas for the milestone post

      Hello Developers, We launched the Kaizen series in 2019 to share helpful content to support your Zoho CRM development journey. Staying true to its spirit—Kaizen Series: Continuous Improvement for Developer Experience—we've shared everything from FAQs
    • Kaizen #193: Creating different fields in Zoho CRM through API

      🎊 Nearing 200th Kaizen Post – We want to hear from you! Do you have any questions, suggestions, or topics you would like us to cover in future posts? Your insights and suggestions help us shape future content and make this series better for everyone.
    • Client Script | Update - Introducing Commands in Client Script!

      Have you ever wished you could trigger Client Script from contexts other than just the supported pages and events? Have you ever wanted to leverage the advantage of Client Script at your finger tip? Discover the power of Client Script - Commands! Commands

    Nederlandse Hulpbronnen


      • Recent Topics

      • Is there a way to request a password?

        We add customers info into the vaults and I wanted to see if we could do some sort of "file request" like how dropbox offers with files. It would be awesome if a customer could go to a link and input a "title, username, password, url" all securely and it then shows up in our team vault or something. Not sure if that is safe, but it's the best I can think of to be semi scalable and obviously better than sending emails. I am open to another idea, just thought this would be a great feature.  Thanks,
      • Single Task Report

        I'd like a report or a way to print to PDF the task detail page. I'd like at least the Task Information section but I'd also like to see the Activity Stream, Status Timeline and Comments. I'd like to export the record and save it as a PDF. I'd like the
      • Auto-response for closed tickets

        Hi, We sometimes have users that (presumably) search their email inbox for the last correspondence with us and just hit reply - even if it's a 6 month old ticket... - this then re-opens the 6 month old ticket because of the ticket number in the email's subject. Yes, it's easy to 'Split as new Ticket', but I'd like something automated to respond to the user saying "this ticket has already been resolved and closed, please submit a new ticket". What's the best way to achieve this? Thanks, Ed
      • How to Push Zoho Desk time logged to Zoho Projects?

        I am on the last leg of my journey of finally automating time tracking, payments, and invoicing for my minutes based contact center company - I just have one final step to solve - I need time logged in zoho desk to add time a project which is associated
      • Cannot access KB within Help Center

        Im working with my boss to customize our knowledge base, but for some reason I can see the KB tab, and see the KB categories, but I cannot access the articles within the KB. We have been troubleshooting for weeks, and we have all permissions set up, customers
      • Export to excel stored amounts as text instead of numbers or accounting

        Good Afternoon, We have a quarterly billing report that we generate from our Requests. It exports to excel. However if we need to add a formula (something as simple as a sum of the column), it doesn't read the dollar amounts because the export stores
      • why my account is private?

        when i post on zohodesk see only agent only
      • Getting ZOHO Invoice certified in Portugal?

        Hello, We are ZOHO partners in Portugal and here, all the invoice software has to be certified by the government and ZOHO Invoice still isn´t certified. Any plans? Btw, we can help on this process, since we have a client that knows how to get the software certified. Thank you.
      • 500 Internal Server Error

        I have been trying to create my first app in Creator, but have been getting the 500: Internal Server Error. When I used the Create New Application link, it gave me the error after naming the application. After logging out, and back in, the application that I created was in the list, but when I try to open it to start creating my app, it gives me the 500: Internal Server Error. Please help! Also, I tried making my named app public, but I even get the error when trying to do that.
      • Client Script | Update - Client Script Support For Portals

        Dear All! We are excited to announce the highly anticipated feature: Client Script support for Portals. We understand that many of you have been eagerly awaiting this enhancement, and we are pleased to inform you that this support is now live for all
      • Professional Plan not activated after payment

        I purchased the Professional Plan for 11 users (Subscription ID: RPEU2000980748325) on 12 September 2025, and the payment has been successfully processed. However, even after more than 24 hours, my CRM account still shows “Upgrade” and behaves like a
      • Zoho Books - France

        L’équipe de Zoho France reçoit régulièrement des questions sur la conformité de ses applications de finances (Zoho Books/ Zoho Invoice) pour le marché français. Voici quelques points pour clarifier la question : Zoho Books est un logiciel de comptabilité
      • how to edit the converted lead records?

        so I can fetch the converted leads records using API (COQL), using this endpoint https://www.zohoapis.com/crm/v5/coql and using COQL filter Converted__s=true for some reasons I need to change the value from a field in a converted lead record. When I try
      • Auto Update Event Field Value on Create/Edit

        Hi there, I know this question has been posted multiple times and I've been trying many of the proposed similar scripts for a while now but nothing seems to work... what might I do wrong? The error I receive is this: Value given for the variable 'meetingId'
      • Pre-orders at Zoho Commerce

        We plan to have regular producs that are avaliable for purchase now and we plan to have products that will be avaliable in 2-4 weeks. How we can take the pre-orders for these products? We need to take the money for the product now, but the delivery will
      • Constant color of a legend value

        It would be nice if we can set a constant color/pattern to a value when creating a chart. We would often use the same value in different graph options and I always have to copy the color that we've set to a certain value from a previous graph to make
      • Zoho Pagesense really this slow??? 5s delay...

        I put the pagesense on my website (hosted by webflow and fast) and it caused a 5s delay to load. do other people face similar delays?
      • Payroll and BAS ( Australian tax report format )

        Hello , I am evaluating Zoho Books and I find the interface very intuitive and straight forward. My company is currently using Quickbooks Premier the Australian version. Before we can consider moving the service we would need to have the following addressed : 1.Payroll 2.BAS ( business activity statement ) for tax purposes 3.Some form of local backup and possible export of data to a widely accepted format. Regards Codrin Mitin
      • Problem with Email an invoice with multiple attachments using API

        I have an invoice with 3 attachments. When I send an email manually using the UI, everything works correctly. I receive an email with three attachments. The problem occurs when I try to initiate sending an email using the API. The email comes with only
      • Page Layouts for Standard Modules like CRM

        For standard modules like quotes, invoices, purchase orders, etc, it would be a great feature to be able to create custom page layouts with custom fields in Zoho Books similar to how you can in Zoho CRM. For example, and my current use case, I have a
      • Non-depreciating fixed asset

        Hi! There are non-depreciable fixed assets (e.g. land). It would be very useful to be able to create a new type of fixed asset (within the fixed assets module) with a ‘No depreciation’ depreciation method. There is always the option of recording land
      • Fixed asset management

        I want to know if there is any individual module for fixed assets management
      • One time sale item in billing automatically detects as service

        if i have some items which i don't want to add in my "item" list because its sold only for one time. but when i type item name in invoice, it (system) automatically takes it as a service and despite of HSN , it shows SAC code to be entered. if its selectable i.e. either item or service , it would be very helpful and a must have feature.
      • Project template after project creation

        How can I apply a project template AFTER the project has been created?
      • convert the project to templet

        i have some deployment ME product for different customer , i need to create a fixed template for use it rather then keeping creating this template every time
      • Is there a notification API when a new note is addeding

        Trying to push to Cliq, or email notification when there's a new note added in module. How to implement this?
      • Seriously - Create multiple contacts for leads, (With Company as lead) Zoho CRM

        In Zoho CRM, considering a comapny as a lead, you need us to allow addition of more than one contact. Currently the Lead Section is missing "Add contact" feature which is available in "Accounts". When you know that a particular lead can have multiple
      • Related Module in Sharing Rules

        Zoho CRM team recently added the feature to filter records by Related Records It will be really beneficial if we can have this feature for Sharing Rules as well
      • Assignment Thresholds Resetting After Lead Conversion

        Hello everyone, We're facing an issue with Zoho CRM's lead assignment thresholds that makes them unsuitable for our workflow. I'm hoping to find a potential workaround or solution from the community. Here’s our current process: A new lead is created automatically
      • Vendor Signatures Needed for Purchase Orders

        Hello everyone, We have a unique requirement that necessitates that Vendors & Suppliers formally acknowledge our Purchase Orders upon receipt. I was hoping that there would be an option to do so in Zoho Books, but that does not appear to be the case.
      • Zoho CRM Analytics - Allow To Reorder Dashboards

        I would like to suggest that you add the ability to reorder dashboards in the Analytics Module. I can see that this has been requested some time ago, the latest 9 years ago. I am not sure if this is a big or small endeavor, but such a small fix can go
      • Territory view for custom modules?

        I have recently activated territories however I can't seem to find how to use territories for custom modules? These modules have territories:  Contacts /  Accounts / Opportunities These modules don't have territories:   Buildings (custom module) and 
      • Zoho Books - How to Invoke a Custom Function in Schedulers

        We have multiple schedulers that send emails to customers in batches. Currently, we are maintaining the same code across several schedulers. Is it possible to use a custom function inside a scheduler script? If yes, how can we invoke the custom function
      • Approval Process Comments

        Is it possible to view the comments entered during the approval or rejection of a record in the approval process? If not, is there a way to require a field to be completed upon approval or rejection?
      • Login for test case

        Had a few questions regarding authentication test cases and couldn't find an answer in the the docs. 1. If an app like Zoho Creator requires authentication before providing access, do I need to create a login function and add it to each test case? 2.
      • Zoho / Outlook Calendar sync

        The current Marketplace -> Microsoft -> Meetings integration needs 2 changes. 1. The current language for the Two-Way sync option should be changed. It currently states, "Sync both your Zoho CRM Calendar and Office 365 Calendar meetings with each other."
      • GST Slabs Redefined: Stay Compliant Using Zoho Books!

        Hello Everyone! The Government of India is rolling out new GST rates, a major reform aimed at simplifying the current tax structure starting 22 September 2025. GST will move from four slabs (5%, 12%, 18%, 28%) to two main slabs (5% and 18%), plus a special
      • Please make it easier to Pause syncing

        right now it takes 3 clicks to get there. sounds silly, but can you make it just 2 clicks to get it done instead? thats how dropbox does it, 2 clicks to pause instead of 3.
      • Customer members area

        Does FSM support a customer members area? If not what do you propose we use if we want the data used in FSM for customers to give them an area / login to see past orders, create new orders and general announcements.
      • Zoho Books-Accounting on the Go Series!

        Dear users, Continuing in the spirit of our 'Function Fridays' series, where we've been sharing custom function scripts to automate your back office operations, we're thrilled to introduce our latest initiative – the 'Zoho Books-Accounting on the Go Series'.
      • Next Page