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

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

Hello everyone!

Welcome back to another week of Kaizen.
In this post, we explore the Multi-Module Lookup (MML) field in the Appointments module of Zoho CRM. You learn what an MML field is, how it works, and how to use it with Zoho CRM APIs.



Table of Contents:

  • What is a Multi-Module Lookup (MML) Field in Zoho CRM?
  • Use Cases for MML
  • How  the "Appointment For" (MML) field in the "Appointments" module works?
  • Creating a Record in the Appointments Module Using the Insert Records API
  • Retrieving a Record from the Appointments Module Using the Get Records API
  • Multi-module Lookup Using the COQL API
  • Multi-module Lookup Using the Bulk Read API
  • Frequently Asked Questions

What is a Multi-Module Lookup (MML) Field in Zoho CRM?

A Multi-Module Lookup (MML) field in Zoho CRM allows you to create a one-to-one relationship between a record in one module and a record from one of multiple other modules. Unlike a normal lookup field, which references a single module, an MML field can dynamically reference records from multiple modules. 
Without the MML field, users must create multiple lookup fields for each module, which complicates the CRM layout and user experience.

Note:
  • The multi-module lookup (multi_module_lookup) data type was introduced in Zoho CRM API version 3.
  • Currently, the MML field is available as a system-defined field named Appointment For in the Appointments module. 
  • The Appointment For field supports lookups to both Contacts and custom modules.
  • You cannot create a custom MML field in Zoho CRM.


Data Model Representation

MML's Data Model Representation

Use Cases for MML


Zylker Healthcare is a multi-specialty hospital that uses Zoho CRM to maintain its appointment scheduling process. 

In this setup, Zylker maintains two key modules:
  • Contacts module - Stores records of physicians and surgeons, including attending physicians, specialists, and surgeons who diagnose and refer patients.
  • Patients module - A custom module used to maintain records of all patients.

To improve the appointment booking process, Zylker uses the "Appointment For" Multi-Module Lookup (MML) field in the Appointments module. This field lets Zylker manage an appointment with either a Physician/Surgeon or a Patient, eliminating the need for multiple lookup fields.

How  the "Appointment For" (MML) field in the "Appointments" module works?

  • When creating an appointment, the user selects the "Appointment For" field.
  • The field displays records based on the selected module, either the Contacts or  Patients. 
  • The user selects the appropriate record (Contact or Patients) for the appointment.
  • A related list is automatically created in the selected module (Contact or Patients) as the Open Activities / Closed Activities to display all appointments associated with that record.

Creating a Record in the Appointments module using the Insert Records API

Before creating a record in the Appointments module via the Insert Records API, make sure you know the API names of the system-defined mandatory fields. These fields are required to create an appointment successfully.

System-defined Mandatory Fields:
  • Appointment_For (MML field)
  • Service_Name
  • Appointment_Start_Time
  • Appointment_Name
  • Member
  • Location

The below image shows how these system-defined mandatory fields appear in the Appointments module UI:

System-defined mandatory keys in the Appointments Module in UI view.

API calls you have to make before creating a record:

Before inserting a record into the Appointments module, it is important to know the API names of the fields and their parent modules. 

i. Use the GET - Module Metadata API to know the API name of the module. In our case, the Appointments module.

Request URL : {api-domain}/crm/v8/settings/modules
Request Method : GET

Sample Response :

 
In the API response, search for the module with "module_name": "Appointments" and check the value of the "api_name" key to get the API name of the module. This is the name you will use in all related API calls.

ii. Use the GET - Fields Metadata API and get fields metadata for the Appointments module. Here, you can find the API names of the mandatory fields along with other fields present in the Appointments module. 

Below is the API call & response for the multi-module lookup field along with other mandatory fields.

Request URL : {api-domain}/crm/v8/settings/fields?module=Appointments__s
Request Method : GET

Sample Response :


Note: The above image highlights only the key properties of the Multi-Module Lookup (MML) field from the field metadata response. The complete API response contains additional properties not shown here.

In the response:
  • The multi-module lookup field is identified by the key "data_type" with the value "multi_module_lookup".
  • The associated modules supported by the MML field (e.g., Contacts, Patients) are listed under the "modules" key.
  • Other mandatory fields like Service Name, Appointment Name, and Appointment Start Time can be identified by "system_mandatory": true.
The keys of the above multi_module_lookup JSON object are explained below:


"multi_module_lookup": {
    "display_label": "Appointments", // Display label of the module where the MML field is used
    "api_name": "Appointments__s", // API name of the Appointments module
    "modules": [ //List of modules associated with the Appointments module. 
        {
            "api_name": "Contacts", //API name of the associated module 
            "module_name": "Contacts", // Display Name of the module 
            "id": "5725767000000002179" //Unique ID of the module
        },
        {
            "api_name": "Patients", //API name of the associated custom module
            "module_name": "Patients", //Display label of the module
            "id": "5725767000006473007" //Unique module ID
        }
    }
]
},

Note: 
  • You cannot add or remove modules from the Multi-Module Lookup (MML) field using APIs. These actions are only available through the Zoho CRM UI.
  • Once a module is disassociated from the MML field, existing records associated with that module will remain in the Appointments module, and you will no longer be able to associate newly created records from the disassociated module using the MML field. 
The remaining system-defined mandatory fields, along with their API names, are listed below.

 

 System-defined Mandatory Field Names

 

 

System-defined Mandatory Field API Names

Service Name

Service_Name

Appointment Start Time

Appointment_Start_Time

Appointment Name

Appointment_Name

Member

Owner

Location

Location


Note: The system-defined mandatory fields can be identified by "system_mandatory": true.

Search the system-defined mandatory field names and get their API names.
With the field API names, use the following request and sample input body to create a record in the Appointments module using the Insert Records API.

Request URL : {{api-domain}}/crm/v8/Appointments__s
Request Method : POST

Request Body :

{
    "data": [
        {
            "Appointment_Name": "General Consultation",
            "Owner": {
                "name": "Patricia Boyle",
                "id": "5725767000000411001",
                "email": "patricia@zohotest.com"
            },
            "Appointment_Start_Time": "2025-04-15T13:00:00-07:00",
            "Appointment_End_Time": "2025-04-15T13:30:00-07:00",
            "Appointment_For": {
                "module": {
                    "api_name": "Contacts",
                    "id": "5725767000000002179"
                },
                "name": "John Doe",
                "id": "5725767000005607020"
            },
            "Service_Name": {
                "name": "General Check-up",
                "id": "5725767000006387029"
            },
            "Location": "Business Address"
        }
    ]
}


Sample Response:


{
    "data": [
        {
            "code": "SUCCESS",
            "details": {
                "Modified_Time": "2025-05-06T20:33:42-07:00",
                "Modified_By": {
                    "name": "Patricia Boyle",
                    "id": "5725767000000411001"
                },
                "Created_Time": "2025-05-06T20:33:42-07:00",
                "id": "5725767000006390001", //Unique ID if the newly created record. Please note that this record ID will be used in the following API get and update operations.
                "Created_By": {
                    "name": "Patricia Boyle",
                    "id": "5725767000000411001"
                }
            },
            "message": "record added",
            "status": "success"
        }
    ]
}



Note:
Only Contacts and custom modules are supported in the Multi-Module Lookup field. If you try to associate a new record with a module that has been removed from the MML field or an unsupported module in the MML field, the following error will be thrown. 


Retrieving a Record from the Appointments Module Using the Get Records API

Request URL : {{api-domain}}/crm/v8/Appointments__s/5725767000006390001
Request Method: GET

Request Response:

{
    "data": [
        {
            "Owner": {
                "name": "Patricia Boyle",
                "id": "5725767000000411001",
                "email": "patricia@zoho.com"
            },
            "$currency_symbol": "$",
            "Address": null,
            "Appointment_Start_Time": "2025-04-15T13:00:00-07:00",
            "Cancellation_Reason": null,
            "$field_states": null,
            "Appointment_For": {
                "module": {
                    "api_name": "Contacts",
                    "id": "5725767000000002179"
                },
                "name": "John Doe",
                "id": "5725767000005607020"
            },
            "Rescheduled_To": null,
            "$sharing_permission": "full_access",
            "Reschedule_Reason": null,
            "Additional_Information": null,
            "Last_Activity_Time": null,
            "Cancelled_Time": null,
            "Cancellation_Note": null,
            "Modified_By": {
                "name": "Patricia Boyle",
                "id": "5725767000000411001",
                "email": "patricia@zoho.com"
            },
            "Reschedule_Count": 0,
            "Rescheduled_By": null,
            "id": "5725767000006390001",
            "Rescheduled_Time": null,
            "Remind_At": null,
            "Appointment_End_Time": "2025-04-15T13:30:00-07:00",
            "Status": "Overdue",
            "Modified_Time": "2025-05-06T20:04:38-07:00",
            "Service_Name": {
                "name": "General Check-up",
                "id": "5725767000006387029"
            },
            "Created_Time": "2025-05-06T20:04:38-07:00",
            "testing": null,
            "Rescheduled_From": null,
            "Cancelled_By": null,
            "$editable": true,
            "Appointment_Name": "General Consultation",
            "Duration": 30,
            "Record_Status__s": "Available",
            "Created_By": {
                "name": "Patricia Boyle",
                "id": "5725767000000411001",
                "email": "patricia@zoho.com"
            },
            "Tag": [],
            "Location": "Business Address",
            "Reschedule_Note": null
        }
    ]
}


Updating MML Field Value Using the Update Records API

Request URL : {{api-domain}}/crm/v8/Appointments__s/5725767000006390001
Request Method: PUT

Request Body:

{
    "data": [
        {
            "Appointment_Start_Time": "2025-04-16T14:00:00-07:00", //Updating the Appointment_Start_Time
            "Appointment_End_Time": "2025-04-16T14:30:00-07:00", //Updating the Appointment_End_Time
            "Appointment_For": {
                "module": {
                    "api_name": "Employees", //Updating a different module
                    "id": "5725767000002161028"
                },
                "name": "Patrica", //A record from the Employees module
                "id": "5725767000006272001" //unique ID of the record
            }
        }
    ]
}


Multi-module Lookup Using the COQL API

Querying Inner Fields of Linked Modules within the MML Field

With the COQL API, you can query inner fields of linked modules within a Multi-Module Lookup (MML) field. This provides deeper insights into related fields data in a module. This query support is available from Zoho CRM API Version 7.

Sample Query:


{
 "select_query": "select 'Appointment_For->Contacts.Lead_Source' from Appointments__s where id is not null"
}

The above query retrieves the Lead Source field from the Contacts module within the Appointment_For MML field. 


Sample Response:



Querying Multi-Module Lookup Module Name

Querying the module name associated with each record in a Multi-Module Lookup (MML) field. This query support is available from Zoho CRM API Version 7.

Sample Query:

{
"select_query": "select Appointment_For.module.api_name, Appointment_For from Appointments__s where id is not null"
}


The Appointment_For.module.api_name returns the module name (e.g., Contacts or Accounts) for each record linked in the Appointment_For MML field.

Sample Response:


Multi-module Lookup Using the Bulk Read API

Bulk Read API allows you to fetch a large set of data i.e., you can fetch a maximum of 2,00,000 records in a single API call. 
Specify the API name of the Appointments module in the module JSON object when making API calls. Refer to the following section for an example.

Request Method : POST

Request Body :

{
    "callback": {
        "method": "post"
    },
    "query": {
        "module": {
            "api_name": "Appointments__s" //API name of the Appointments module
        },
        "file_type": "csv"
    }
}


Note: The Appointment_For field cannot be used in the criteria.

As the API is an asynchronous API, the response will not be available instantly; the bulk read job is scheduled, and the status can be checked. Once the job is completed, you will be notified in the callback URL. The records are available in a downloadable CSV file or ICS file (for events). See the Bulk Read API document to know how to view the status of the scheduled job and download the file, along with more sample requests and responses.

Sample Exported Response 



Frequently Asked Questions

1. Which modules are currently supported in the MML field?

Only Contacts and custom modules can be associated with an MML field.

2. What error is thrown if I try to associate a record with a removed or unsupported module in the MML field?

If you try to associate a record with a removed or unsupported module in an MML field, the system will throw an "INVALID_DATA" error.

3. Is the MML field available for all modules?

No, as of Zoho CRM API Version 8, the MML field is available only as a system-defined field in the Appointments module.

4. How do I get the list of modules associated with an MML field?

You can use the GET - Fields Metadata API for the Appointments module and look for the field with "data_type" : "multi_module_lookup" and check its "modules" JSON array.

5. Can I add or remove modules from a Multi-Module Lookup (MML) field via API?

Adding or removing modules in an MML field is not supported via API. These actions can only be done through the Zoho CRM UI.

6. What happens if I remove a module from an MML field?

If a module is removed from the MML through Zoho CRM UI, it can no longer be associated with new records, but existing records linked to that module will remain unaffected.

7. Is MML field supported in the Bulk Write API?

As of Zoho CRM API Version 8, the MML field is available only in the Appointments module as a system-defined field. The Appointments module is not supported in the Bulk Write API.

8. Is MML field supported in the Search API?

The MML field is not currently supported in the Search API.



We trust that this post meets your needs and is helpful. Let us know your thoughts in the comment section or reach out to us at support@zohocrm.com

Stay tuned for more insights in our upcoming Kaizen posts!

Cheers!!!


Related Readings:


    • Sticky Posts

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

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

    • Kaizen #217 - Actions APIs : Tasks

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

    • Kaizen #216 - Actions APIs : Email Notifications

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

    • Kaizen #152 - Client Script Support for the new Canvas Record Forms

      Hello everyone! Have you ever wanted to trigger actions on click of a canvas button, icon, or text mandatory forms in Create/Edit and Clone Pages? Have you ever wanted to control how elements behave on the new Canvas Record Forms? This can be achieved

    • Kaizen #142: How to Navigate to Another Page in Zoho CRM using Client Script

      Hello everyone! Welcome back to another exciting Kaizen post. In this post, let us see how you can you navigate to different Pages using Client Script. In this Kaizen post, Need to Navigate to different Pages Client Script ZDKs related to navigation A.

    • Recent Topics

    • Where can we specify custom CSS in Zoho Forms custom theme ?

      I'm using a form with a dark theme. The OTP popup window is unreadable, because for some reason, the OTP popup background fixes color to white, but still takes the font color specified in the custom theme. This ends up as white on white for me, rendering

    • Automating Employee Birthday Notifications in Zoho Cliq

      Have you ever missed a birthday and felt like the office Grinch? Fear not, the Cliq Developer Platform has got your back! With Zoho Cliq's Schedulers, you can be the office party-cipant who never forgets a single cake, balloon, or awkward rendition of

    • Drop Down Value

      Hi, May I know why Zoho Flow treat this drop down as number and not as string. If so, how can I fetch the right value for filtering. This field is from Creator, in Creator upon checking by default it is a string since it's not a lookup field.

    • SMS to customers from within Bigin

      Hi All, Is there anyone else crying out for Bigin SMS capability to send an SMS to customers directly from the Bigin interface? We have inbuilt telephony already with call recordings which works well. What's lacking is the ability to send and receive

    • Zoho Survey reminder settings are extremely confusing

      Hi, I just want to set 3 reminders, one week apart from the first email out. Your form is too confusing and I don't understand. Can you simplify and be more specific regarding the language used on the form ?

    • Add deluge function to shorten URLs

      Zoho Social contains a nice feature to shorten URLs using zurl.co. It would be really helpful to have similar functionality in a Deluge call please, either as an inbuilt function or a standard integration. My Creator app sends an email with a personalised

    • Add specific field value to URL

      Hi Everyone. I have the following code which is set to run from a subform when the user selects a value from a lookup field "Plant_Key" the URL opens a report but i want the report to be filtered on the matching field/value. so in the report there is

    • form data load issue when saving as duplicate record is made

      Hello. I have a form with a lookup when a value is selected the data from the corresponding record is filled into all of the fields in the form. But the form is loaded in such a state that if any value is changed it will take all of the values pre loaded

    • Unable to remove the “Automatically Assigned” territory from existing records

      Hello Zoho Community Team, We are currently using Territory Management in Zoho CRM and have encountered an issue with automatically assigned territories on Account records. Once any account is created the territory is assigned automatically, the Automatically

    • Track online, in-office, and client location meetings separately with the new meeting venue option

      Hello everyone! We’re excited to announce meeting enhancements in Zoho CRM that bring more clarity and structure to how meetings are categorized. You can now specify the meeting venue to clearly indicate whether a meeting is being held online, at the

    • Google Fonts Integration in Pagesense Popup Editor

      Hello Zoho Pagesense Team, We hope you're doing well. We’d like to submit a feature request to enhance Zoho Pagesense’s popup editor with Google Fonts support. Current Limitation: Currently, Pagesense offers a limited set of default fonts. Google Fonts

    • Improved Contact Sync flow in Google Integration with Zoho CRM

      Hello Everyone, Your contact sync in Google integration just got revamped! We have redesigned the sync process to give users more control over what data flows into Google and ensure that this data flows effortlessly between Zoho CRM and Google. With this

    • Pro Lite Upgrade - Quick Access Tray

      Hello, I was going to upgrade to Pro Lite but the Quick Access Tray feature isn't available for Windows. Of the four features not available for Windows, the QAT is what I'm most interested in. Are there plans to add this feature for Windows anytime soon?

    • Custom Fonts in Zoho CRM Template Builder

      Hi, I am currently creating a new template for our quotes using the Zoho CRM template builder. However, I noticed that there is no option to add custom fonts to the template builder. It would greatly enhance the flexibility and branding capabilities if

    • Improved Functionality PO Bill SO Invoice

      Hello, I need to enter over 100 items, it's frustrating to scroll a few item rows and wait for more to load, then scroll again. It would be nice to have buttons that scroll to the top or bottom with one click. Furthermore, these items I'm adding are VAT

    • Wishes for 2026

      Hello, and a happy new year 2026! Let's hope it's better for everyone. I'd like to share some thoughts on Zoho One and what could be useful in the short, medium, and long term. Some things are already there, but not applied to Zoho One. Others seem like

    • How to Integrate Zoho Books with Xero (No Native Connection Available)

      Hi everyone, I’m currently facing an issue with integrating Zoho Books invoices with Xero, as I’ve noticed Zoho does not provide a native integration with Xero at this time. I would like to ask: What are the common or recommended solutions for syncing

    • How to install Widget in inventory module

      Hi， I am trying to install a app into Sales Order Module related list, however there is no button allow me to do that. May I ask how to install widget to inventory module related list?

    • error while listing mails

      I can't access email in any of my folders: Oops, an error occurred - retry produces the second error response: error while listing mails (cannot parse null string). I've signed in and out of Zoho, restarted my iMac.

    • Unlocking New Levels: Zoho Payroll's Journey in 2025

      Every year brings its own set of challenges and opportunities to rethink how payroll works across regulations and teams. In 2025, Zoho Payroll continued to evolve with one clear focus: giving businesses more flexibility, clarity, and control as they grow.

    • Introducing Connected Records to bring business context to every aspect of your work in Zoho CRM for Everyone

      Hello Everyone, We are excited to unveil phase one of a powerful enhancement to CRM for Everyone - Connected Records, available only in CRM's Nextgen UI. With CRM for Everyone, businesses can onboard all customer-facing teams onto the CRM platform to

    • Send Supervisor Rule Emails Within Ticket Context in Zoho Desk

      Dear Zoho Desk Team, I hope this message finds you well. Currently, emails sent via Supervisor Rules in Zoho Desk are sent outside of the ticket context. As a result, if a client replies to such emails, their response creates a new ticket instead of appending

    • CRM project association via deluge

      I have created a workflow in my Zoho CRM for closing a deal. Part of this workflow leverages a deluge script to create a project for our delivery team. Creating the project works great however, after or during the project creation, I would like to associate

    • Zoho Browser??

      hai guys, this sounds awkward but can v get a ZOHO BROWSER same as zoho writer, etc. where i can browse websites @ home and continue browsing the same websites @ my office, as v have the option in Firefox, once i save and close the browser and again when i open it i will be getting the same sites. If u people r not clear with my explanation, plz let me know. Thanks, Sandeep  

    • MCP no longer works with Claude

      Anyone else notice Zoho MCP no longer works with Claude? I'm unable to turn this on in the claude chat. When I try to toggle it on, it just does nothing at all. I've tried in incognito, new browsers, etc. - nothing seems to work.

    • Enable History Tracking for Picklist Values Not Available

      When I create a custom picklist field in Deals, the "Enable History Tracking for Picklist Values" option is not available in the Edit Properties area of the picklist. When I create a picklist in any other Module, that option is available. Is there a specific reason why this isn't available for fields in the Deals Module?

    • The reason I switched away from Zoho Notebook

      My main reason for switching to Zoho was driven by three core principles: moving away from US-based products, keeping my data within India as much as possible, and supporting Indian companies. With that intent, I’ve been actively de-Googling my digital

    • Add RTL and Hebrew Support for Candidate Portal (and Other Zoho Recruit Portals)

      Dear Zoho Recruit Team, I hope you're doing well. We would like to request the ability to set the Candidate Portal to be Right-to-Left (RTL) and in Hebrew, similar to the existing functionality for the Career Site. Currently, when we set the Career Site

    • Ability to Edit YouTube Video Title, Description & Thumbnail After Publishing

      Hi Zoho Social Team, How are you? We would like to request an enhancement to Zoho Social that enables users to edit YouTube video details after the video has already been published. Your team confirmed that while Zoho Social currently allows editing the

    • Free Webinar : Unlock AI driven business insights with Zoho Inventory + Zoho Analytics

      Are you tired of switching between apps and exporting data to build customized reports? Say hello to smarter & streamlined insights! Join us for this exclusive webinar where we explore the power of the Zoho Inventory–Zoho Analytics integration. Learn

    • Critical Issue: Tickets Opened for Zoho Support via the Zoho Help Portal Were Not Processed

      Hi everyone, We want to bring to your attention a serious issue we’ve experienced with the Zoho support Help Portal. For more than a week, tickets submitted directly via the Help Portal were not being handled at all. At the same time no alert was posted

    • Hide/Show Subform Fields On User Input

      Hello, Are there any future updates in Hide/Show Subform Fields "On User Input"?

    • Cloning Item With Images Or The Option With Images

      Hello, when I clone an item, I expect the images to carry over to the cloned item, however this is not the case in Inventory. Please make it possible for the images to get cloned or at least can we get a pop up asking if we want to clone the images as

    • Archiving Contacts

      How do I archive a list of contacts, or individual contacts?

    • WorkDrive and CRM not in sync

      1/ There is a CRM file upload field with WorkDrive file set as the source: 2/ Then the file is renamed in WorkDrive (outside CRM): 3/ The File in CRM is not synced after the change in WorkDrive; the file name (reference) in CRM record is not updated (here

    • 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'

    • Adding Default Module Image into mail merge field

      As with most people finding their way to these forums i have a specific requirement that doesn't seem to be supported by Zoho I have created 2 custom modules to suit my purpose 1 is an inventory type module that lists aluminium extrusions, and all relevant

    • Sync Data from MA to CRM

      Currently, it's a one-way sync of data from the CRM to MA. I believe we should have the ability to select fields to sync from MA to the CRM. The lead score is a perfect example of this. In an ideal world we would be able to impact the lead score of a

    • Is it possible to roll up all Contact emails to the Account view?

      Is there a way to track all emails associated with an Account in one single view? Currently, email history is visible when opening an individual Contact record. However, since multiple Contacts are often associated with a single Account, it would be beneficial

    • Update CRM record action

      Currently, MA only offers a "Push Data" action to push data to a CRM module. This action is built to cover the need to both create a new record and update an existing record. Because it has been implemented this way all required fields on the CRM module

    • Next Page