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

    • Can we handle a support like (incident management) project in Zoho Projects?

      Hi, I have a new profile of a project whereby we provide "ticket" base support to a client. They have a request and ideally we would handle comms via a email exchange logged in Zoho. Today we use Zoho Projects for all out projects, which means that we

    • Trying to show the actual Terms & Conditions on PDF

      Hi, On Zoho forms I am trying to have the actual terms and conditions that the user needs to accept also show on the pdf that they receive after. Right now it only says "Agreed". Please help.

    • Installing EMAIL Setup in New Domain

      Respected Support team, I'm facing an issue with cloudflare in Pakistan, I want to setup Zoho Mail Setup but I Don't know how to enable Zoho mail setup without cloudflare. My Website https://stumbleguyzzapk.com/, https://fakservices.com/ is using CF,

    • Enhancements to Zoho Meeting Annotator

      Hello Zoho Meeting Team, Hope you are doing well. We would like to share a few improvement suggestions regarding the Zoho Meeting Annotator used during screen sharing. While the current version provides helpful annotation tools, there are several limitations

    • Cliq iOS can't see shared screen

      Hello, I had this morning a video call with a colleague. She is using Cliq Desktop MacOS and wanted to share her screen with me. I'm on iPad. I noticed, while she shared her screen, I could only see her video, but not the shared screen... Does Cliq iOS is able to display shared screen, or is it somewhere else to be found ? Regards

    • Triggering rules on lead conversion

      There is no field on the Rule list for rule conversion to trigger an alert on liead conversion to a potential. I assigned a rule to file on any creation or update of a lead. The lead was changed a lead to a potential but no rule was fired. Rajesh Bhadra

    • Add "Fetch Composite Item" Action for Inventory

      I want to make a Flow that uses information returned in the GET call for Composite Items, and it's not currently available in Zoho Flow. Please consider adding this functionality.

    • Zoho Social/Marketing Plus - Addition to "Monitor" function

      It would be very helpful if the Monitor function would allow us to add a column to monitor hashtags in addition to pages and mentions. This is a common and very valuable function in other social listening tools.

    • Almacenamiento

      Hola, Quisiera saber como podría hacer para bajar el almacenamiento de 5gb a mis usuarios, en otras palabras los quiero ir limitando de la cuota real, y luego ir agregando poco a poco la cantidad hasta llegar a los 5gb que me dan en el plan free. 

    • Zoho Invoice Now Supports VeriFactu for Businesses in Spain

      Starting from January 1, 2026, Spain requires real-time invoice reporting for all B2B transactions. From July 2026, this requirement will extend to B2C transactions as well. All reporting must be carried out through the VeriFactu to AEAT (Agencia Estatal

    • Will I Get a Refund If I Downgrade Zoho Mail?

      Hello, We upgraded an email account for our new employee. However, the employee left after one month, and now I've reduced the number of Zoho Mail users from 7 to 6. Can we get a refund for the remaining portion of our annual payment?

    • Zoho Billing Now Supports VeriFactu for Businesses in Spain

      Starting from January 1, 2026, Spain requires real-time invoice reporting for all B2B transactions. From July 2026, this requirement will extend to B2C transactions as well. All reporting must be carried out through the VeriFactu to AEAT (Agencia Estatal

    • how to add subform over sigma in the CRM

      my new module don't have any subform available any way to add this from sigma or from the crm

    • Introducing the revamped What's New page

      Hello everyone! We're happy to announce that Zoho Campaigns' What's New page has undergone a complete revamp. We've bid the old page adieu after a long time and have introduced a new, sleeker-looking page. Without further ado, let's dive into the main

    • 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

    • Name autocomplete

      Hi, During searching emails the web tool does not always propose the auto-completion of the saved emails. As a result I either have to go to contacts and look up the exact email, or the exact full name including the middle name and any dots, which is very annoying. For example I have a contact that I emailed in the past that has "First M. Last" <email@email.com> type of contact. When I start typing 'First' the email may or may not pop up in the autocomplete menu. Then if I start typing "first last"

    • Using a CRM Client Script Button to create a Books Invoice

      Hello, I need help handling error messages returned to my client script from a function. The scenario I have setup a client script button which is available from each Deal. This CS executes a crm function, which in turn creates an invoice based on the

    • Possible to connect Zoho CRM's Sandbox with Zoho Creator's Sandbox?

      We are making some big changes on our CRM so we are testing it out in CRM's Sandbox. We also have a Zoho Creator app that we need to test. Is it possible to connect Zoho CRM's Sandbox to Zoho Creator's Sandbox so that I can perform those tests?

    • How do i follow up my email campaign in-thread

      Is there a way to follow up the email campaign so that it is in-thread using zoho campaigns? eg customer gets original email with subject line "hello" then 5 days later follow up would be with subject line "RE: hello".

    • Announcing new features in Trident for Mac (1.29.0)

      Hello everyone! Trident for macOS (v1.29.0) is here with new features and enhancements to enhance your business communication. Let's take a quick look at them. Access shared mailboxes. You can now view and access shared mailboxes in Trident, which are

    • Books is extremely slow again today !

      Everything is running slowly even with 500mb connection speed

    • Cyclic dependencies in many-to-many relationships...

      I have an application which includes a form for companies, and a form for contacts. Each company can be assigned 1 technical and 1 administrative contact. I have this working okay so far, but I want to copy the scripts used so far to a new empty application. When I import the scripts it fails with a message that says: Problem encountered while creating the application Error in resolving form dependency:Cyclic dependency among the forms:[Company, Contact] What can I do to resolve this? After all,

    • Zoho Workdrive for Office, "vsto runtime not found"

      Hi all, I have been trying to get ZohoWorkdrive_MS-addin_1.4.exe installed, but I keep getting the error "VSTO Runtime Not Found!" - even though I have installed it ... Anyone else hear had problems with the MS addin?  FYI, I am using O365 on A Dell laptop running Win 10 Home - fully patched and up-to-date.  I have tried compatibility modes and running explicitly as Administrator - the usual steps. Any advice would be appreciated.

    • Zia’s AI Assist now helps you write clearer notes — in seconds

      After helping recruiters craft job descriptions, emails, and assessments, Zia’s AI Assist is now stepping in to make note-taking effortless too. Whether you’re recording feedback after an interview or sharing quick updates with your team, you can now

    • Zoho API to create ticket

      I'm developing an integration to create tickets via API, but, locally it works (send and recieve requests). In production it also works sending requests, but, my file don't recieve any response data. My URL is available in Zoho API Console and I have

    • Automate Timesheet Approvals with Multi-level Approval Rules

      Introducing Approval Rules for Timesheets in Zoho Projects. With this automation, teams can manage how timesheets are reviewed and approved by setting up rules with criteria and assigning approvers to handle submissions. Timesheet, when associated to

    • Building Toppings #1 - Serving your needs with Bigin Toppings

      Hey Biginners! We're excited to kick off our Developer Community series on building toppings for Bigin, and our goal is to provide an accessible, beginner-friendly, and relevant path for every developer. Imagine creating tiny pieces of software that unlock

    • Can we create Sprint with tasks from Multiple projects?

      Hi Team, We were using Zoho Sprints for quite sometime. Currently we have started the process of Sprint method. We couldnt create the active sprint board with the tasks from multiple projects. I would like to know whether this is possible or Any timeline

    • Tip of the Week #74– Create automated workflows in MS Power Automate

      Zoho TeamInbox now connects directly with Microsoft Power Automate, letting you streamline everyday routines tasks such as from sending emails to managing threads, with automated workflows. About the integration Zoho TeamInbox integrates with Microsoft

    • Account validation

      Hello everyone, I registered my account on ZeptoMail to use the system, but the problem is that the verification period on Zepto's end has already passed and I have limited functionality.

    • Paste issues in ZOHO crm notes

      Hi, since a week or so I have issues with the paste function in ZOHO CRM. I use "notes" to copy paste texts from Outlook emails and since a week or so, the pasting doesnt function as it should: some text just disappears and it gives a lot of empty lines/enters.....

    • Is it possible to add a gradient color to a newsletter im designing?

      From where i sit it looks like you can only choose a single color but not combine 2 colors?

    • New Feature: Audit Log in Zoho Bookings

      Greetings from the Zoho Bookings team! We’re excited to introduce Audit Log, a new feature designed to help you track all key actions related to your appointments. With Audit Log, you can maintain transparency, strengthen security, and ensure accountability.

    • Custom validation in CRM schema

      Validation rules in CRM layouts work nicely, good docs by @Kiran Karthik P https://help.zoho.com/portal/en/kb/crm/customize-crm-account/validation-rules/articles/create-validation-rules I'd prefer validating data input 'closer to the schema'

    • Customised Funnel

      We are running the standard plan for our ZOHO CRM. I have been asked if there is a way to combine data from the Calls module, Deals module and Contact Module into 1 funnel, similar to the view you can get when viewing Deals By Stages, you can see the

    • Account disabled

      I have an issue I need help with. Whilst trialing ZOHO CRM I created the following: Account1 (-------------) using m__ame@m__rg___s__i__.___.__ and 2 personal emails Account2 (-------------) using a personal email and 2 users _al__1@______________._o_.__

    • Blocked Email

      We are a Zoho One subscriber and use Yahoo as our MX provider. A few times each year, for the past four years, CRM blocks one or more of my Zoho One users from receiving internal email from CRM. This includes "@mentions" in all modules, and emails from

    • message var is empty in bot mention handler

      Hi, I'm encountering a problem: in my bot's mention handler, I want to retrieve the text the user typed when mentioning the bot. Example: On the #tests-cyril channel, I send this message: “@Donna hello how are you ?” I expect the system variable "message"

    • Remembrance Day to Remember – Recalling Values

      The phrase “at the eleventh hour” refers to the 11th hour of the 11th day of the 11th month in 1918, when the hostilities of World War I came to an end—but it still holds meaning today. Remembrance Day (Veterans Day in the US) is observed on November

    • Enhancing Zia's service with better contextual responses and article generation

      Hello everyone, We are enhancing Zia's Generative AI service to make your support experience smarter. Here's how: Increased accuracy with Qwen One of the key challenges in AI is delivering responses that are both contextually accurate and empathetic while

    • Next Page