Kaizen #189: Manipulating Multi-Module Lookup (MML) Field using Zoho CRM APIs

Kaizen #189: Manipulating Multi-Module Lookup (MML) 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 #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.

    • Kaizen #226: Using ZRC in Client Script

      Hello everyone! Welcome to another week of Kaizen. In today's post, lets see what is ZRC (Zoho Request Client) and how we can use ZRC methods in Client Script to get inputs from a Salesperson and update the Lead status with a single button click. In this

    • Kaizen #222 - Client Script Support for Notes Related List

      Hello everyone! Welcome to another week of Kaizen. The final Kaizen post of the year 2025 is here! With the new Client Script support for the Notes Related List, you can validate, enrich, and manage notes across modules. In this post, we’ll explore how

    • Kaizen #217 - Actions APIs : Tasks

      Welcome to another week of Kaizen! In last week's post we discussed Email Notifications APIs which act as the link between your Workflow automations and you. We have discussed how Zylker Cloud Services uses Email Notifications API in their custom dashboard.

    • Kaizen #216 - Actions APIs : Email Notifications

      Welcome to another week of Kaizen! For the last three weeks, we have been discussing Zylker's workflows. We successfully updated a dormant workflow, built a new one from the ground up and more. But our work is not finished—these automated processes are

    • Recent Topics

    • Zoho CRM for Everyone's NextGen UI Gets an Upgrade

      Hello Everyone We've made improvements to Zoho CRM for Everyone's Nextgen UI. These changes are the result of valuable feedback from you where we’ve focused on improving usability, providing wider screen space, and making navigation smoother so everything

    • [Webinar] Solving business challenges- Handling the challenge of transitioning to Zoho Writer from legacy tools

      Moving to Zoho Writer is a great way to consolidate your business tools and become more agile. With multiple accessibility modes, no-code automation, and extensive integration with business apps and content platforms, Zoho Writer helps solve your organization's

    • hide resolution from help centre

      to my surprise, i just found out that the resolution text is public in the helpcenter, even if 'notify customer' is off. is there a workaround to that? how do others deal with this? How zoho support does this and I don't think its used by Zoho in the first place. the resolution is meant to be private, not public

    • Feature Request - Gift Cards or Gift Voucher Capability in Zoho Commerce

      Hi Zoho Commerce team, I'm comming accross more and more retail businesses who sell gift cards. As there is currently no way to manage this in Zoho Commerce, it is a blocker to addoption. This is particularly popular in Europe and North America. I recently

    • Highlight a candidate who is "off limits"

      Hello: Is there a way to highlight a candidate who is "off limits"?  I would like to have the ability to make certain candidate and / or Client records highlighted in RED or something like that.   This would be used for example when we may have placed a candidate somewhere and we want everyone in our company to quickly and easily see that they are off limits.  The same would apply when we want to put a client or former client off limits so no one recruits out of there. How can this be done? Cheers,

    • Closing off tasks automatically based on project status

      Is there a way to close off all open tasks when a project is set as Cancelled?

    • How to add tabular data when execute Add Record API

      Hi everyone! I was send api updateRecord follow by this request url : https://people.zoho.com/people/api/forms/json/<formLinkName>/updateRecord with parameters "inputData", "tabularData", "recordId". Ex picture below And response success: But. When I

    • CRM x WorkDrive: File storage for new CRM signups is now powered by WorkDrive

      Availability Editions: All DCs: All Release plan: Released for new signups in all DCs. It will be enabled for existing users in a phased manner in the upcoming months. Help documentation: Documents in Zoho CRM Manage folders in Documents tab Manage files

    • [Free webinar] Understanding connections and datasources in Zoho Creator - Creator Tech Connect

      Hello everyone, We’re excited to invite you to another edition of the Creator Tech Connect webinar. About Creator Tech Connect The Creator Tech Connect series is a free monthly webinar featuring in-depth technical sessions designed for developers, administrators,

    • Bridge the Gap Between your Service and Finance Teams

      In field service, the most expensive distance isn’t the drive to a customer’s home—it’s the gap between a finished job and a paid invoice. Zoho FSM leverages the power of Zoho Invoice to handle and manage billing operations. It enables you to: Instantly

    • Zoho Desk API - Send Reply to CUSTOMERPORTAL

      Hello! I'll try to send a reply to Customer Portal, But the response is 500 (INTERNAL_SERVER_ERROR in service response). {"Error":"{\"errorCode\":\"INTERNAL_SERVER_ERROR\",\"message\":\"An internal server error occurred while performing this operation.\"}"}

    • Direct URL to "View Record"

      I would like to create a button (Deluge Script) to jump to the "view record" without passing by the record menu, but I can not aford to find the right url. I don't want the "view record" as a single page. I want the "view record" in the application like the picture below: Thanks in advance for your help

    • Live Chat for user

      Hi everyone, I’m new to Zoho Creator and wanted to ask if it’s possible to add a live chat option for all logged-in portal users so they can chat internally. I’m trying to create a customer portal similar to a service desk, but for vehicle breakdowns,

    • SalesIQ Chat Owner to CRM Lead Owner Mapping

      There is no proper mapping between the SalesIQ chat owner and the CRM lead owner. When a chat is assigned to an agent, the lead created in CRM is often assigned to a different user, forcing admins to manually change ownership every time. This creates

    • Does zoho inventory need Enterprise or Premium subsrciption to make Widgets.

      We have Zoho One Enterprise and yet we can't create widgets on inventory.

    • Product line search in quotes

      Is there a way to change the search setting when you add a product line to a quote. We have created a field in products called 'Part Number' and I would like when I'm adding a product line to the quote that I can search on that field. At the moment it only searches on product description. In products I can search on the 'Part Number' field Any help welcome.

    • Invoice status on write-off is "Paid" - how do I change this to "Written off"

      HI guys, I want to write off a couple of outstanding invoices, but when I do this, the status of the invoices shows as "Paid". Clearly this is not the case and I need to be able to see that they are written off in the customer's history. Is there a way

    • 🚀 WorkDrive 6.0 (Phase 1): Empowering Teams with Content Intelligence, Automation, Accessibility, and Control

      Hello, everyone! WorkDrive continues to evolve from a robust file management solution into an intelligent, secure, and connected content collaboration platform for modern businesses. Our goal remains unchanged: to simplify teamwork, strengthen data security,

    • Storage Limits

      Hello, What is the storage limitations for each user on professional edition?  Thanks, Mekki

    • Optimum CRM setup for new B2B business

      Can some advise the most common way to setup Zoho CRM to handle sales for a B2B company? Specifically in how to handle inbound/outbound emails. I have spent hours researching online and can't seem to find an accepted approach, or even a tutorial. I have

    • Dheeraj Sudan and Meenu Hinduja-How do I customize Zoho apps to suit my needs?

      Hi Everyone, I'm Meenu Hinduja and my husband Dheeraj Sudan, run a business. I’m looking to tweak a few things to fit my needs, and I’d love to hear what customizations others have done. Any tips or examples would be super helpful! Regards Dheeraj Sudan

    • Important Update: Google Ads & YouTube Ads API Migration

      To maintain platform performance and align with Google's newest requirements, we are updating the Google Ads and YouTube Ads integrations by migrating from API v19 to the newer v22, before the official deprecation of v19 on February 11, 2026. Reference:

    • WhatsApp IM in Zoho Desk always routes to Admin instead of assigned agent

      Hello Zoho Experts, I connected WhatsApp IM to my Zoho Desk account. I only assigned my Customer Service (CS) agent to the WhatsApp channel, and I did NOT include Admin in this channel. However, every new WhatsApp conversation automatically gets assigned

    • Zoho Recruit Community Meetup - London 🇬🇧

      Hello Recruiters! We’re excited to announce that the Zoho Recruit team is coming to the UK for an in-person Zoho User Group (ZUG) Meetup in London! This is your chance to connect with fellow Zoho users, learn from experts, and walk away with actionable

    • Power Pivot and Data Modeling functionality in Zoho Sheet

      When will MS Excel functionalities like Power Pivot and Data Modeling functionalities be available in Zoho Sheet?

    • Sender Email Configuration Error.

      Hello Team, Hope you are all doing well. We are in the process of creating the Zoho FSM environment in the UAE. When we try to add the sender email address “techsupportuae@stryker.com”, we receive the error message: “Error occurred while sending mail

    • Canvas View bug

      I would like to report a bug. When clone a canvas view from an existing canvas view, if the original canvas view have canvas button with client script. Then the new create canvas view will have canvas button, it is make sense. But when I try to delete

    • Global Search placement in the new UI

      Having a hard time with the global search placement in the UI redesign. Surely I can't be the only one. Previously global search placement was perfect. A bar at the top/center of the page. Exactly where you would expect it to be. Since the new UI has

    • What's New - January 2026 | Zoho Backstage

      Welcome to 2026! If you thought last year was big, buckle up. We’re stepping into this year with a singular focus: unimaginable growth, elite scalability, and performance benchmarks that leave the old ways of event management in the rearview mirror. As

    • Cliq on your mobile phone

      Some of the employees in my company get their cliq on their mobile phones but it will not let them answer the call. The employee has to go to their laptop to access it. 

    • Scheduled sending of a poll and its results

      Is there a way to schedule sending a poll to all my users and have the results sent separately to the team?

    • Bulk Delete Messages in Cliq

      Isn't it possible to bulk delete messages in Cliq? I have them delivered to me as notifications from another service but most of them need to be deleted as not of value. I get dozens of them per day, and deleting them is already difficult is the "Delete"

    • stock movement report by each transaction for each item

      Dear Sir we are using zoho inventory for foodstuff and we lack the transaction report which clearly shows movement of an item from Opening balance of the month to Goods received in, Supplier return out, Invoice out, Sales return In, Transfer out and Transfer

    • Select the task view on the board in the Zoho Connect iPhone app

      Hello. How do I select the task view on the board in the Zoho Connect iPhone app? The Android app has this functionality.

    • Unable to change Company Logo

      Hi Guys, I have an issue where I've uploaded a Company image in Gif format and the logo has now got a black background whereas the logo is supposed to be black not the background. I didn't think it would be an issue so I created a PNG version to upload

    • Metadata API Access to Functions

      I think it would be incredibly helpful to have api access to every function's code. Our team primarily uses deluge functions to update fields across modules according to business logic. I would like to create a visual dependancy model for our CRM, but

    • Historical Sales Info - Blend with Finance Invoice Line Items, Access in CRM and Desk

      My company has been using Zoho One since 2021, with sales data going back through 2020. However, we have been in business much longer, and we have historical sales information that we want to have at our fingertips when talking with customers (usually

    • Introducing Record Category in CRM: Group options to see record status at a glance.

      Release update: Currently available for CN, JP, and AU DCs (all paid editions). It will be made available to other DCs by mid-March. Hello everyone, We are pleased to introduce Record Category in Zoho CRM - a new capability where the user can get an overview

    • Change Last Name to not required in Leads

      I would like to upload 500 target companies as leads but I don't yet have contact people for them. Can you enable the option for me to turn this requirement off to need a Second Name? Moderation update (10-Jun-23): As we explore potential solutions for

    • Zoho recruit's blueprint configuration is not functioning as mapped

      Current Status: Zoho Blueprint is not functioning as configured. Issue: We are moving a Candidate status in Zoho Recruit "for active file" but we encountered: "Status cannot be changed for records involved in Blueprint." This happens to various client

    • Next Page