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:


    • Recent Topics

    • Editing the Ticket Properties column

      This is going to sound like a dumb question, but I cannot figure out how to configure/edit the sections (and their fields) in this column: For example, we have a custom "Resolution" field, which parked itself in the "Ticket Information" section of this

    • Copy field information to clipboard

      I need to be able to transfer some field information in to the clipboard, so that I can then paste it in to our helpdesk system. Is there a way I could add a button to a detail report that does this?

    • Issuing reconciling a bank statement

      HELP! I'm trying to reconcile a bank statement. The prior month reconciled perfectly. Beginning balance is correct yet I'm off by the same amount each time. Both myself and my office manager, separately and together, have tried to complete this reconciliation

    • Unknown table or alias 'A1'

      I would like to create a subquery but i am getting the following error: Unknown table or alias 'A1' used in select query. This is the sql statement:  SELECT A1.active_paying_customers, A1.active_trial_customers, A1.new_paying_signup, date(A1.date_active_customers), 

    • Detect and ignore bots in visitors

      The SalesIQ visitor numbers are basically useless to us because there is no bot detection. We get the same bots coming in from the same countries looking at the same pages every day. It can't be that difficult to tell the difference between an actual

    • Add Real-Time Microphone Audio-Level Indicator During Screen Recording

      Hi Zoho WorkDrive Team, Hope you are doing well. We would like to request an important enhancement to the Zoho WorkDrive screen-recording experience. Current Limitation: During a recording session, there is no visual indication that the microphone is

    • Zero Personalization of the File Sharing Experience

      By now (2025) this is the maximum level of personalization available for a Zoho sharing link. We gently asked Zoho if we could modify at least the background, and they replied that it cannot be customized. We're truly disappointed – and surprised every

    • External Share > Edit: Cannot Create Zoho Files

      Hi Zoho, When we create an external share link with Edit permission, our external users are unable to create a Zoho file (Zoho Writer, Zoho Sheet and Zoho Show). They can only upload files. They can edit the Zoho files if we create them internally and

    • Two factor authentication for helpdesk users

      The company i work for wants use the helpdesk site in Zoho desk, as a place for their distribution partners to ask question and look for information about our product. The things there is suppose to go up there is somewhat confidential between my company

    • Users Not Automatically Being Added To WorkDrive Team

      I have already created a ticket for this issue, but the support team doesn't seem to understand what's happening. Our organization started with a trial of Zoho Workplace around November 10, 2025. I created 10 users, including myself. I sent out the invites,

    • Kiosk can't merge picklist or multiselect

      There is no ability to load a multiselect or picklikst field into a kiosk with the values that have been previously selected. So, I essentially have 3 unacceptable options: 1.)Load the value into a text string and include instructions like this: "Picklist

    • AGE field from DATE OF BIRTH Field.

      HI! I have a field called date of birth in my CRM (LEADS, CONTACT etc…)     How can I know the AGE today   I would like to create a field AGE. I now how to create a field but I don´t which calculation (CUSTOM FUCTION) to make ¿ANY HELP?

    • How to update/remove file in zoho creator widgets using javascript API

      Hi Team, I have developed a widget which allows inserting and updating records I have file upload field with multiple file upload. Now while doing insert form record, I am using uploadFile API to upload files for that record. I am using updateRecord API

    • Introducing Enhanced Storage Management

      We’re excited to roll out two new enhancements in Zoho Recruit, Subscription Information and Storage Management — designed to give admins complete visibility into subscription details, feature limits, and storage consumption — all from one place inside

    • Announcing new features in Trident for Windows (v.1.34.4.0)

      Hello Community! Trident for Windows just got better! With this update we have features that make your daily work easier and more efficient. We've added some features that are exclusive to our app and we're sure you'll find them useful. Let’s dive into

    • Report Hover Setting

      Would be great if we will able to show information to the user while hovering a record in a report.

    • Synchronization between Gmail and Zoho Mail

      Hello! I am using Zoho Mail within the Zoho One platform. I have completed the basic setup and added all the required DNS records with our domain provider. Our goal is to set up two-way synchronization between our current Gmail inbox and Zoho Mail, but

    • Vertical images displayed as horizontal

      Some pictures that originally are in vertical position are displayed in horizontal after the upload. It seems that system rotates them by 90 degrees. How can I fix this issue?

    • Zoho Desk iOS app update: Saved filters and sort options

      Hello everyone! Saved filters created on the web(desk.zoho.com) for tickets are now accessible on the Zoho Desk iOS app. You can easily rename, delete, or clear filters on the go. We have also introduced Sort options on the ticket listing screen, allowing

    • Introducing VeriFactu Support in Zoho Books

      Hello users, Spain has introduced the VeriFactu system under Real Decreto 1007/2023 to ensure integrity, traceability, and anti-fraud compliance in e-invoicing. Starting January 1, 2026, all B2B invoices must be reported to Agencia Estatal de Administración

    • Big Things Just Dropped in the SalesIQ Universe: Top Upgrades You’ll Love in Nova’25

      Nova'25 has landed, and it’s packed with meaningful upgrades to help you engage smarter, work faster, and scale with ease. Whether you're into proactive messaging, smarter automation, or better admin control, there's something here for everyone. Here's

    • Time Entries in Analytics

      I am trying to import a zoho sheet into zoho analytics. In my sheets one of the columns has "time Entries" in this "format HH:MM am/pm" example 11:00 PM. After import, i noticed that analytics converted the time to "00 Jan 1900 23:00:00".. how do i maintain

    • Amazon invoice in Zoho Books

      I have just made my first few sales on Amazon India. Amazon Seller account generates invoices for the sales made on Amazon. These invoices are sent to customers also. Now when I was only making offline sales, I used to create Invoices in Zoho Book. Now

    • Zoho Creator Upcoming Updates - November 2025

      Hello everyone, Welcome to your monthly roundup of new features and enhancements! We hope you've already taken a look at Release Projection 2—it details the features coming your way for the rest of the year. And this month, we're excited to start rolling

    • Table dimensions

      I try changing the dimensions of the table on my computer but it doesn't change. Do I have to be a premium member or does it only work on the app?

    • Zoho Webinar + HubSpot : Simplifiez la gestion de vos données de webinaires

      Les webinaires sont aujourd’hui essentiels pour interagir avec vos prospects et vos clients. Cependant, la gestion des données entre plusieurs plateformes peut vite devenir complexe. Grâce à la nouvelle intégration entre Zoho Webinar et HubSpot, vos outils

    • I am trying to give access to one of our educators access to 3 forms in Zoho and she is not able to view the data - Access issue

      Hi Team, When I try to provide read access to one of our educators on Zoho for Pre-training , post training and Impact survey forms submit form access which also allows them to read , it does not show them data

    • How to book GST paid in zoho books

      hi, i am a new user to Zoho books and not able to book GST paid in books, kindly suggest how i can book it in books. thanks, siddharth

    • PUNJAB NATIONAL BANK (CORPORATE) INDIA - NOT AVAILABLE IN BANKING

      Dear sir, Kindly fix it. PUNJAB NATIONAL BANK (INDIA) is available but PUNJAB NATIONAL BANK (CORPORATE) is not available. Kindly enable this banking since we need to categorize the entries. Regards, Sanjay Jena email id/ user id : travewithmerchant@

    • Employment Contract / HRMS Documents - Zoho People

      How do I create customized HR documents for disbursal from Zoho People ? Example, say offer letters ? appointment letters ? Memos ? We want to be able to preset these in one or ther other form and issue them to employees who are in Zoho People.

    • Is it possible to create a word cloud chart in ZoHo Analystics?

      Hi there, I have a volume of transaction text that I would like to analyse using word cloud (or other approcah to detect and present word frequency in a dataset). For example, I have 50,000 records describing menu items in restaurants. I want to be able

    • 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

    • Facturation électronique 2026 - obligation dès le 1er septembre 2026

      Bonjour, Je me permets de réagir à divers posts publiés ici et là concernant le projet de E-Invoicing, dans le cadre de la facturation électronique prévue très prochainement. Dans le cadre du passage à la facturation électronique pour les entreprises,

    • Your bot just got smarter: AI-Powered routing that reads between the lines

      What if your bot could tell the difference? Between a visitor who just needs a quick answer, someone actively comparing options, and a frustrated customer one click away from leaving? Most bots can't. They deliver the same response to everyone, missing

    • Weekly Tips : Master Keyboard Shortcuts in Zoho Mail

      If you spend a lot of time managing emails, switching between your mouse and keyboard can slow you down. Whether you are replying to clients, organizing your inbox, or searching for messages, every second counts. So, how can you streamline your email

    • Introducing custom lookup fields in the Tickets, Contacts, and Accounts modules

      Hello all, We are excited to announce a new enhancement that will empower you to further customize the Tickets, Contacts, and Accounts modules. Now, you will be able to create custom lookup fields in your Tickets, Contacts, and Accounts layouts for more

    • DKIM cannot be enabled for the domain as no verified default selector present

      Can't get the DKIM working. May you please check my account (nksy.us) to see what's wrong?

    • Contacts per department

      Hello, Is it possible to limit Contacts to a Department? Thanks

    • How to restrict user/portal user change canvas view

      Hi , I would like to restrict user / portal user change their canvas view because I hide some sensitive field for them. I dont want my user switch the canvas view that do not belong to them But seems Zoho do not provide this setting?

    • Collections Management: #3 Tackling Payment Failures

      Sam refreshed the dashboard. "Payment failed". Same customer. Same subscription. This is happening for the third time. He sends a usual email: "Your renewal payment failed again. Could you please check and retry?" A couple of days passed, and there was

    • Next Page