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

      • Recurring Invoices

        We are looking at moving our invoices to ZOHO Billing, I have started the trial period and like that I can et up for four different companies. The one feature we need which is mentioned in the documentation is Recurring Invoices so we can send our Rent

      • Implement Meeting Polls in Zoho Bookings

        Dear Zoho Bookings Support Team, We'd like to propose a feature enhancement related to appointment scheduling within Zoho Bookings. Current Functionality: Zoho Bookings excels at streamlining individual appointment scheduling. Users can set availability

      • Zoho Projects App update: Arabic and Hebrew language support

        Hello everyone! In the latest version(v3.10) of the Zoho Projects iOS app update, we have brought in support to access the app in RTL(Right to Left) languages (Arabic and Hebrew). Note: RTL is yet to be supported on the Calendar and Gantt charts modules

      • I want to cancel @mention group in the notes in Zoho CRM

        Hi Everybody, I want to prevent people from mentioning a specific group in notes in Zoho CRM. We have one group called Team Sales, and although we've asked users not to mention groups, they still mention the group name. My workaround is to change the

      • Kaizen #193: Creating different fields in Zoho CRM through API

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

      • How to install node packages in Zoho Creator cloud functions

        I wanted to create some functions which requires node packages like axios, fetch, multer etc., How and where can i install the node packages in Zoho creator to use it in Zoho creator Nodejs function.

      • Session "Ask Me Anything" Zoho France - Le 26 Juin 2025 14h à 17h (en Français

        Chers Utilisateurs, Vous cherchez à mieux comprendre Zoho CRM ou Zoho Desk ? Nos experts seront disponibles pour répondre à toutes vos questions lors de notre session Ask Me Anything. Rejoignez-nous ici pour en discuter en ligne. Pendant trois heures,

      • Option to Crop Existing Agent Image in Zoho One Directory

        Hello Zoho Team, We hope you're all doing well. We would like to request a small but useful enhancement to the Zoho One Directory. 🎯 Current Limitation At present, the system allows cropping an agent image only during the initial upload of an agent's

      • Introducing Sub-Accounts in Zoho Books!

        Hello Everyone, Sub-Accounts is LIVE! Yes, you read it right. The much needed and most requested feature is now live in Zoho Books. The sub-accounts feature in Zoho Books will help you to classify your accounts further which will give you a more detailed view of your accounts while running reports. You can create sub-accounts for the below Accounts: Asset Cost of Goods Sold Expense Liability Fixed Asset Other Asset Other Current Asset Long Term Liability Other Current Liability Other Liability Other

      • Sesión "Ask me anything" Zoho en Español - 26 de junio de 2025, de 14:00 a 17:00 (en español)

        ¡Hola Comunidad! ¿Quieres entender mejor Zoho CRM o Zoho Desk? Nuestros expertos estarán disponibles para responder a todas tus preguntas durante nuestra sesión "Ask me anything". Puedes comentar este artículo y durante tres horas, nuestro equipo estará

      • UI Update: We've Reorganized Invoice Settings

        Dear users, We’ve reorganized invoice settings to offer you a streamlined and intuitive experience when managing your subscriptions. Starting from 2 July 2025, subscription-related invoice settings will be accessible from a new page called Billing Preferences

      • Marketer’s Space – Automate Subscription Management for CRM Contacts Using Workflows in Zoho Campaigns

        Hello, marketers! Welcome back to Marketer’s Space. In this week’s post, we’ll look at how to simplify subscription management using Workflows for contacts synced from Zoho CRM in Zoho Campaigns. There are multiple ways to assign topics to your contacts:

      • WhatsApp to shift to per-message billing from July 1, 2025

        Greetings Recruiters, If you’re using WhatsApp to connect with candidates through Zoho Recruit, there’s an important pricing change coming up that you’ll want to plan for. What’s changing? Starting July 1, 2025, WhatsApp is moving away from conversation-based

      • Implement full RTL support in Zoho Cliq, including text alignment and character positioning, regardless of the interface language.

        Dear Zoho Cliq Support Team, We are writing to request a significant enhancement to the current RTL language support within Zoho Cliq. Currently, while Zoho Cliq allows users to input text in RTL languages, the text alignment remains LTR, resulting in

      • Email Alerts with Affected Flow Details When Deprecating Modules in Zoho Flow

        Dear Zoho Flow Team, We would like to request an enhancement to the module deprecation process in Zoho Flow. 🧩 Current Limitation: Currently, when a module is deprecated by the Flow team: No email notifications are sent. There is no automated way to

      • are there Url parameters to group records in the report/view?

        There are URL parameters to filter records in target report.  Is there any way to group records in report by certain field, using URL parameters or embed report parameters? Or any other workaround, apart from creating second report for dofferent grouping?  Aim: I want to provide user a quick link to re-group embed report by different fields.

      • Setvalue() client script not working

        I have created a client script on the load the record(detail view page). I wanted to populate some default information in the single line field. for that I created the client script. below is the script: var field_obj = ZDK.Page.getField( 'Designation'

      • Power of Automation :: Automate Deal Status Update in Zoho CRM upon Project Completion.

        Hello Everyone, A Custom function is a user-written set of code to achieve a specific requirement. Set the required conditions needed as when to trigger using the Workflow rules (be it Tasks / Project) and associate the custom function to it. Requirement:

      • Leverage the power of Zia (AI) to create Marketing Projects in Zoho Marketing Plus

        Hey everyone, Zoho's advanced AI assistant, Zia, now works with OpenAI to offer personalized marketing activity suggestions for your marketing projects in Brand Studio. With information such as your campaign's objective, duration, marketing channel types,

      • Use Zoho Flow to Supercharge your Zoho FSM Integrations

        We are thrilled to announce that Zoho FSM is now included in Zoho Flow - Zoho’s powerful no-code integration platform. With this, you can connect Zoho FSM with your most-used applications—without requiring technical expertise. What does this offer? Zoho

      • Zoho Flow triggers not working

        Hi , I have set up a flow which triggers when a new record is created in a Zoho Creator app. This flow works great when I initiate the flow with  "test and debug". However the flow does not trigger in live mode.  I have tested all the connections used

      • Can you sync your Apple Calendar with Bigin Activities/calendar?

        I've searched everything I can find and nothing is coming up... I've got a number of things in my calendar for the future, and it would be easiest if I can sync between them to update my availability for my booking page (also syncing the other way would

      • How to track salesiq on google analytics without GTM

        Hello! We had to move the installation of the SalesIQ widget from GTM to directly do it in our wordpress site. The SalesIQ widget was being blocked by Adblockers which caused a lot of our visitors to not be able to see it. This issue was fixed from deleting

      • Custom Module Count

        We are on Zoho One. CRM says that the three modules which support Zoho Sign integration are "custom modules." Do these count against the 200 custom modules permitted by the One access to "enterprise-level" CRM features?

      • Marketer's Space: Bookmarks by Zoho Campaigns

        Hello Marketers, In this week's Marketer's Space, we'll look at a simple yet powerful feature that makes a big difference in your workflow: Bookmarks. Bookmarks is a built-in feature in Zoho Campaigns that enables you to create a personalized library

      • I need a custom AI Chatbot to be integrated with ChatGPT to Handle Customers inquiries

        I need a custom AI Chatbot to be integrated with ChatGPT to handle Customer inquiries, and save the data to Zoho CRM as a Leads, Also to schedule a demo with clients and more options

      • User Management > Agents request

        I have a few suggestions for the Agent page: 1) Please add a way to filter Full agents. The list currently shows Light agents as an option but sometimes it would be helpful to view only the full agent licenses or non-light agent. 2) Add the ability to

      • Mandate Assessments in Zoho Recruit's Candidate Application Form

        We're excited to announce the Include Assessment option for the Candidate Application Form, which lets you display the pre-screening assessment associated with the job opening along with the application form fields. This ensures that every candidate applying

      • Sending an email from contacts does not display the recipient's name correctly

        When I select a contact or group of contacts and then click the envelope to send mail, the contacts are added to the To section of a new email. Unfortunately, their First and last names are not displayed. The part of the email address before the @ sign

      • Writing SQL Queries - After Comma Auto Suggesting Column

        When writing SQL Queries, does anyone else get super annoyed that after you type a comma and try to return to a new line it is automatically suggest a new column, so hitting return just inputs this suggested column instead of going to a new line? Anyone

      • Stop adding Default ID column to xls exports

        When anything is exported to xls, Zoho adds a column with an ID. WE DO NOT WANT THIS COLUMN. We use an automated report to a team. We have our own tracking number. 1. This makes the report messy, it just pushes OUR data off to the right. 2. We have to

      • communication distribution

        Hello community! Request for help - how to resolve the issue of subscribing to specific content. I use ZOHO CRM and ZOHO CAMPAIGNS to send email communications to my customers. I only purchased ZOHO CAMPAIGNS after using the CRM for some time and I have

      • Truesync for Linux

        Is Truesync available on linux ?

      • Web access blocked

        Hello, My account (chris@thewebprojects.com) has been blocked due to security reasons. Please see attached. Can you kindly please help me. Thank you in advanced

      • How to determine ZohoCreator organization ID

        I am trying to setup an API to interface with my ZohoCreator app by following the self-client credential flow here https://www.zoho.com/accounts/protocol/oauth/self-client/client-credentials-flow.html However, it requires me to input my organization ID.

      • Autofill Zoho form with Zoho campaign data

        Hello, I send campaigns and we have set a button called "Demo" in that campaign. This button leads to a form. Since we have the data in Zoho Campaign, would it be possible that some fields of the form (first+last name, email, company) are automatically filled when our readers click on this button? If yes, how could I do that? Thanks Aurélie Leyendecker

      • Need to be Amount Adjusted with same Group Comany

        Dear Sir/ Madam, Good Day, Example wise i write my quire Below A B C & D E F Bothe are Same Group Companies We Paid 50000 AED to ABC Company but we received Invoice 48000 AED worth of material Balance 2000 AED invoice i received from D E F. I Need to

      • Transfer between 2 accounts in forein currency

        Hello, While abroad, I have exchanged some money in a money exchange service from a foreign currency (MYR) to another foreign currency (USD) without passing through my base currency (CHF). How do I record this transaction in Zoho Books? When I try to

      • Zoho Books Webhook in Custom Module doesn't work

        I have a custom module "Purchase Request" in Zoho Books in which we're trying to convert status of the PRs to Draft and Pending Approval. We've explored different applications and custom functions but found that the status is not "writable". However,

      • Issue with Missing Scope for Creating Service Report via Zoho FSM API

        Hello @Latha Velu , I am currently working on creating a connection to create a Service Report in Zoho FSM using the API. However, while configuring the required scopes, I noticed that the scope ZohoFSM.modules.ServiceReports.CREATE which

      • Next Page