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

    • How to display two measures (sales and price) divided by categories on one line chart

      Hi everyone, I’m having trouble figuring out how to display two columns on a line chart with category breakdowns. What I need is a line chart where one line represents Sales and the other represents Price. However, the Price data is divided into around

    • Create custom rollup summary fields in Zoho CRM

      Hello everyone, In Zoho CRM, rollup summary fields have been essential tools for summarizing data across related records and enabling users to gain quick insights without having to jump across modules. Previously, only predefined summary functions were

    • Introducing the locking option for CRM records

      Last modified on 06/04/2023: Record locking option in CRM is now available for all Zoho CRM users in all DCs. Note that it was an early access feature available only upon request. Hello All, Hope you're doing well! We're thrilled to introduce our latest

    • Two new enhancements in Zoho CRM: Introducing new criteria for user fields and displaying group information in users page

      Announcement moderated on 14th June, 2023. Dear All, These enhancements are opened for all users in all DCs. ------------------------------------------------------------------------------------- Dear All, Hope you're well! We are here with two useful

    • Tip #49- Navigating the Remote Support Dashboard in Zoho Assist- 'Insider Insights'

      The Remote Support dashboard in Zoho Assist is designed to help technicians quickly access, manage, and monitor all their support sessions from a single, intuitive interface. Whether you’re starting a new session, managing ongoing connections, or reviewing

    • BMI formula

      I've been trying for hours to calculate BMI using height and weight as my only inputs. It's a simple calculation and I even went to ChatGPT to help me figure this out in Zoho Forms, but it led me down a path of "try this" and "try this". None of my attempts

    • SEO on blogs

      Hello, google is not able to find my blogs. Can you advice me if I need to change some settings or anything else to make it retrievable via SEO many thanks, hans

    • Duplicated Notebooks

      Out of the blue, almost all of my notebooks got duplicated and the different copies contain different information. Some seem like older copies than the others. I use the linux desktop app and sometimes the Android app. I assume that the sync failed at some point and was unable to merge the two versions together. But I'm afraid to add anything else to my notebook because if it can't properly sync 5 notebooks with only a handful of notes each, what will happen when I have hundreds of notes and I lose

    • Samsung Keyboard Issues with Notebook

      Dear Users, We're sorry to inform you that some of our users are experiencing certain issues like scrolling, delay/lag, cursor placement especially within the text notes. This occurs mainly due to Samsung Keyboard compatibility with Android 13 and some

    • Mind mapping in Zoho Projects

      Good morning,   I would like to congratulate the Zoho team for building such an inovative and responsive application that fits in the daily challenges of so many work groups. I would like suggest you another functionality that helps a lot in project planning and development: mind mapping. Mind mapping would be of great help for brianstorming, knowledge management and other needs in online collaboration.   Thanks and wish you all the best! George Maha Empresa Júnior Multidisciplinar do Instituto de

    • Retainer invoice in Zoho Finance modlue

      Hello, Is there a way of creating retainer invoices in the Zoho Finance module? If not can I request this is considered for future updates please.

    • What's New in Zoho Inventory | August – October 2025

      Hello customers, The last quarter has been incredibly productive! We've released a powerful slate of new features and enhancements in Zoho Inventory designed to give you better control, greater efficiency, and expanded functionality across your inventory

    • Documents don't sync properly

      Hello, My team recently moved to Zoho workDrive, some of my team, work remotely so we believed Zoho would be the best way to share and edit files as well as access files withing the team. However we are experiencing sync issues, when a file is uploaded in the file explorer and shows sync complete, same file can be seen on the Zoho web app but other team members can't see the said file because it is not syncing properly. i figured out that if i were to go to preferences in settings and resync the

    • We are looking for an experienced Zoho Developer

      Hi Everyone! We’re on the lookout for a skilled Zoho Developer with hands-on experience in the Zoho Developer Platform (The Vertical CRM Platform) and if you don't know what that is, then you are not the person we are looking for. You would also need

    • Initiate approval workflow after "on edit --> on success"

      Dear Community,  currently I am working on a initiative tracker which should handle approval workflows based on different initiative status. As far as I understand, an approval workflow can be triggered (only?) when data is entered for the input form to the database.  Example: A new initiative is created and submitted. --> Approval Workflow triggered Here comes my question: Is it also possible to trigger an approval workflow if the form was "simply" updated? (on edit --> on success) Imagine the initiative

    • Tax Deductible Donations to a Charity Organisation

      For Australia, what's the best/proper method for entering an expense that is a tax deductible donation to a charitable organisation. And thus is appears correctly in Accounts and BAS as a GST payable deduction?

    • Simultaneous use of WhatsApp Account in SalesIQ and ZohoDesk

      Hi, We have only one number registered in Meta, it's possible use same account for two apps? All times here we try is stopping in SalesIQ. Regards,

    • External lookup fields to synchronise with Analytics

      Hello. I suggest adding external lookup custom fields to the Zoho Analytics integration settings. Currently, these types of fields are not available for synchronisation, so they cannot be used to generate reports with related tables in Analytics. Thank

    • We should have an option to Toggle Off KB Article Links in AI Answer Bot Replies

      Hi everyone, I'm creating this topic to share a feature idea that I think would improve the customer experience when using the AI Answer Bot for self-service. The Current Behavior (The Problem) Currently, when the AI Answer Bot generates a summary or

    • Boot Loop After Removing Service from Client via Admin

      We have multiple laptops experiencing a boot loop / unable to login after the Zoho Remote service was removed from their machine remotely via the desktop client. The Windows sign-in screen is not available, and users are unable to login. This seems like

    • Request Backend Correction — Domains Mapped to Same Help Center (Multi-Brand Setup Failure)

      Hello Zoho Desk Support Team, I need assistance correcting a domain-to-brand mapping issue in our Zoho Desk instance (The Blue Ribbon Project). Both of our verified domains currently point to the same Help Center instead of separate brand portals. Current

    • is there any option to enable the participants interact - can write on the screen, while the screen is shared by the host?

      this is most expected features - for teaching children. is there any option to enable the participants interact - can write on the screen, while the screen is shared by the host?

    • How to disable the Login button in Desk Helpcenter

      Hey there, I'm testing out whether the help center within Zoho Desk could replace our existing Customer FAQ. I tried to customize the themes for the public help center frontend, but stumbled across the login button in the navigation bar. Is there any

    • Very long loading times | bad performance [ZOHO DC: EU]

      Hello there, we have recently noticed that the loading times have become extremely long when retrieving tickets and ticket details. For example, I open any ticket and get the following view. The subject and standard information (ticket owner, status etc.)

    • Client Portal ZOHO ONE

      Dear Zoho one is fantastic option for companies but it seems to me that it is still an aggregation of aps let me explain I have zoho books with client portal so client access their invoice then I have zoho project with client portal so they can access their project but not their invoice without another URL another LOGIN Are you planning in creating a beautiful UI portal for client so we can control access to client in one location to multiple aps at least unify project and invoice aps that would

    • Subforms in stateless forms

      I think the title says it all. We need to be able to add subforms to stateless forms. Currently the only workaround is to create a Form and delete each record upon submission of the form. I need to build an interface to update our inventory. Basically

    • Standard Payment Term is not pulled from account to quotation

      Hey Team There seems to be something off. I do have "Net 30" as my default payment term in Zoho Books for my customers. If, from the customer overview or quote section, I create a new Quotation, the payment terms field stays blank and doesn't get the

    • Zoho Analytics Export API

      Hi Team, I’m working on some integration tasks and wanted to confirm if it’s possible to retrieve a Zoho Analytics table as JSON data using a Deluge script. I’ve already stored my custom data from multiple sources and combined it into a single source.

    • Best way to display complex Bookings Consultation Descriptions on Zoho Site?

      I am a new user so apologies if this has been asked before. I couldn't find any answers in the forum. We offer 18 complex Consultations to our subscribers. Our current platform lets me put detail on these Consultations thoroughly (200-300 words) during

    • Gmail is ramping up its email sender policy as of November 2025

      Hello marketers, As you may be aware, Gmail introduced a guideline for bulk senders starting February 2024. If not, here's a quick refresher straight from Google: After this policy was announced first in 2023 and soft-implemented in February 2024, we

    • Modifying iframe data of Zoho booking iframe

      Hello, I have integrated a Zoho Bookings embedded iframe into my website. Currently, I am pre-filling the booking form with default values as part of our process flow. However, I want to ensure that if an input field is already populated with a default

    • Zoho CRM Workflow and Function Backup Options

      Hi everyone! I have been able to make several backups of my CRM data and noticed that the Workflows and Functions are not included in these backups. To my knowledge, there is no backup feature for workflows and functions, which is problematic in of itself.

    • Enhance Sign CRM integration

      Hello all, I'm working on a custom Deluge script to enhance the integration between Zoho CRM and Sign by using a writer merge template for additional flexibility. I want to replicate the post-sign document integration that exists between CRM and Sign

    • YouTube Live streaming? how to? Zoom has this feature, built-in. Can't find it on zoho meetings.

      YouTube Live streaming? how to? Zoom has this feature, built-in. Can't find it on zoho meetings.

    • Is or will be possible to associate meeting transcription and summary, made by Zia, to meeting/contact/account record in CRM?

      Would be useful to keep context and track jobs, better if it will be auto

    • Desk Field Not Showing in Analytics

      Hi there, I recently added a field to our Zoho Desk Ticket Information. I went and added the data retrospectively to the tickets. It is also marked as required, so all new tickets cannot be closed off without it being filled in. When I try to run a report

    • Export data using advanced export options and customizable settings

      Hello everyone, The user interface for exporting data has been revamped with updates to make data exports more flexible and efficient for users. These updates not only enhance usability but also bring advanced capabilities to help users extract precise

    • Moving data from one pipeline to another

      Hey all, I've got some complex pipelines to build and I'd like to seperate them into seperate pipelines rather than have one mammoth one. If I create 2 pipelines, is there any easy way to use the output of Pipeline1 to be the input into Pipeline2? Or

    • How to export/find all deluge code.

      Hi, I have a large app wich contains several forms, reports, html views, I need to find thow my application if any contains specific word, I could find it manually by editing app and see on every section(field code, on succes, on load, etc) but I would like to do it faster. Is there a way to at least export it to a file the whole deluge code on my application?

    • Have Some Bugs in Zoho CRM Ask Zia Assistant

      Hi Support Team, I have found some bugs in Zoho CRM Ask Zia Feature Please Check below screenshot, insight option is showing twice i think its in early access that's why its have some bugs .

    • Next Page