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 #198: Using Client Script for Custom Validation in Blueprint

      Nearing 200th Kaizen Post – 1 More to the Big Two-Oh-Oh! 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.

    • Kaizen #226: Using ZRC in Client Script

      Hello everyone! Welcome to another week of Kaizen. In today's post, lets see what is ZRC (Zoho Request Client) and how we can use ZRC methods in Client Script to get inputs from a Salesperson and update the Lead status with a single button click. In this

    • 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

    • Recent Topics

    • Highlight a candidate who is "off limits"

      Hello: Is there a way to highlight a candidate who is "off limits"?  I would like to have the ability to make certain candidate and / or Client records highlighted in RED or something like that.   This would be used for example when we may have placed a candidate somewhere and we want everyone in our company to quickly and easily see that they are off limits.  The same would apply when we want to put a client or former client off limits so no one recruits out of there. How can this be done? Cheers,

    • Closing off tasks automatically based on project status

      Is there a way to close off all open tasks when a project is set as Cancelled?

    • [Free webinar] Understanding connections and datasources in Zoho Creator - Creator Tech Connect

      Hello everyone, We’re excited to invite you to another edition of the Creator Tech Connect webinar. About Creator Tech Connect The Creator Tech Connect series is a free monthly webinar featuring in-depth technical sessions designed for developers, administrators,

    • Bridge the Gap Between your Service and Finance Teams

      In field service, the most expensive distance isn’t the drive to a customer’s home—it’s the gap between a finished job and a paid invoice. Zoho FSM leverages the power of Zoho Invoice to handle and manage billing operations. It enables you to: Instantly

    • Direct URL to "View Record"

      I would like to create a button (Deluge Script) to jump to the "view record" without passing by the record menu, but I can not aford to find the right url. I don't want the "view record" as a single page. I want the "view record" in the application like the picture below: Thanks in advance for your help

    • Live Chat for user

      Hi everyone, I’m new to Zoho Creator and wanted to ask if it’s possible to add a live chat option for all logged-in portal users so they can chat internally. I’m trying to create a customer portal similar to a service desk, but for vehicle breakdowns,

    • SalesIQ Chat Owner to CRM Lead Owner Mapping

      There is no proper mapping between the SalesIQ chat owner and the CRM lead owner. When a chat is assigned to an agent, the lead created in CRM is often assigned to a different user, forcing admins to manually change ownership every time. This creates

    • Product line search in quotes

      Is there a way to change the search setting when you add a product line to a quote. We have created a field in products called 'Part Number' and I would like when I'm adding a product line to the quote that I can search on that field. At the moment it only searches on product description. In products I can search on the 'Part Number' field Any help welcome.

    • 🚀 WorkDrive 6.0 (Phase 1): Empowering Teams with Content Intelligence, Automation, Accessibility, and Control

      Hello, everyone! WorkDrive continues to evolve from a robust file management solution into an intelligent, secure, and connected content collaboration platform for modern businesses. Our goal remains unchanged: to simplify teamwork, strengthen data security,

    • Storage Limits

      Hello, What is the storage limitations for each user on professional edition?  Thanks, Mekki

    • Zoho Recruit Community Meetup - London 🇬🇧

      Hello Recruiters! We’re excited to announce that the Zoho Recruit team is coming to the UK for an in-person Zoho User Group (ZUG) Meetup in London! This is your chance to connect with fellow Zoho users, learn from experts, and walk away with actionable

    • Power Pivot and Data Modeling functionality in Zoho Sheet

      When will MS Excel functionalities like Power Pivot and Data Modeling functionalities be available in Zoho Sheet?

    • Global Search placement in the new UI

      Having a hard time with the global search placement in the UI redesign. Surely I can't be the only one. Previously global search placement was perfect. A bar at the top/center of the page. Exactly where you would expect it to be. Since the new UI has

    • What's New - January 2026 | Zoho Backstage

      Welcome to 2026! If you thought last year was big, buckle up. We’re stepping into this year with a singular focus: unimaginable growth, elite scalability, and performance benchmarks that leave the old ways of event management in the rearview mirror. As

    • Cliq on your mobile phone

      Some of the employees in my company get their cliq on their mobile phones but it will not let them answer the call. The employee has to go to their laptop to access it. 

    • Bulk Delete Messages in Cliq

      Isn't it possible to bulk delete messages in Cliq? I have them delivered to me as notifications from another service but most of them need to be deleted as not of value. I get dozens of them per day, and deleting them is already difficult is the "Delete"

    • stock movement report by each transaction for each item

      Dear Sir we are using zoho inventory for foodstuff and we lack the transaction report which clearly shows movement of an item from Opening balance of the month to Goods received in, Supplier return out, Invoice out, Sales return In, Transfer out and Transfer

    • Select the task view on the board in the Zoho Connect iPhone app

      Hello. How do I select the task view on the board in the Zoho Connect iPhone app? The Android app has this functionality.

    • Unable to change Company Logo

      Hi Guys, I have an issue where I've uploaded a Company image in Gif format and the logo has now got a black background whereas the logo is supposed to be black not the background. I didn't think it would be an issue so I created a PNG version to upload

    • Metadata API Access to Functions

      I think it would be incredibly helpful to have api access to every function's code. Our team primarily uses deluge functions to update fields across modules according to business logic. I would like to create a visual dependancy model for our CRM, but

    • Historical Sales Info - Blend with Finance Invoice Line Items, Access in CRM and Desk

      My company has been using Zoho One since 2021, with sales data going back through 2020. However, we have been in business much longer, and we have historical sales information that we want to have at our fingertips when talking with customers (usually

    • Introducing Record Category in CRM: Group options to see record status at a glance.

      Release update: Currently available for CN, JP, and AU DCs (all paid editions). It will be made available to other DCs by mid-March. Hello everyone, We are pleased to introduce Record Category in Zoho CRM - a new capability where the user can get an overview

    • Service disruption in Zoho Cliq (EU Region) – February 9, 2026

      Hello everyone, We’d like to inform you about a brief service disruption that affected Zoho Cliq users in the EU region earlier today. The issue has been resolved, and all services are now operating normally. Summary On February 9, 2026, Zoho Cliq experienced

    • Spotlight series #26 - Build slides with visual clarity using Diagram

      Hello all! The feature in the spotlight this month is Diagram. Let's say you are a part of a project kickoff meeting and your teammate starts explaining the project life cycle like this: "First we ideate, then we create an initial prototype and share

    • Client scripts for Zoho Books ?

      Good day everyone, I am looking for a way to be able to interact with the Quotes and Invoices as they are being created. Think of it like Zoho client script in Zoho CRM. But for the life of me I dont see a way to do this. The issue with having function

    • Uplifted homepage experience

      Editions: All editions. Release Note: Available in CA and SA DCs (Standard, Professional). Availability update (17th February 2026): The feature has been enabled for the following DCs: All editions in the CA and SA DC | Free, Standard and Professional

    • Unable to produce monthly P&L reports for previous years

      My company just migrated to Books this year. We have 5+ years financial data and need to generate a monthly P&L for 2019 and a monthly P&L YTD for 2020. The latter is easy, but I'm VERY surprised to learn that default reports in Zoho Books cannot create

    • Crossbeam

      Does anyone use Crossbeam with their Zoho CRM? I'm looking for a way to import Crossbeam partner leads into Zoho CRM. If so: - What's your experience been like? - Are you able to automatically import Crossbeam leads > Zoho CRM? How? - What doesn't work

    • Access forms within a form

      I have multiple forms that I would like to create access to for users within one form. Example: I have forms A, B, C, D. I would like to create a form with the links to forms A, B, C, & D. That way we can send one link and then the user can select the

    • WorkDrive issues with Windows Explorer Not Responding

      We are using WorkDrive to collaborate on editing video content. We have a lot of files and quite a few are a few gigs. Recently anytime I try and work with the files Explorer freezes for a couple minutes whether it's dragging the files into Premiere or

    • Issues with Actions By Zoho Flow

      Hi, I have a workflow that fires when a deal reaches a stage. This then sends out a contract for the client to sign. I have connected this up through Actions by Zoho Flow. Unfortunately this fails to send out. I have tracked it down to the date fields.

    • Fill Mail Merge document up with subform fields of an Inventory module record being in the Related List

      Hi, I try to insert subform fields from an inventory module record being on the Related List of another inventory module record into a Mail Merge template without success. For example: we use ratecards in licensing and this ratecard items are available

    • Enhancements for Currencies in Zoho CRM: Automatic exchange rate updates, options to update record exchange rates, and more

      The multi-currency feature helps you track currencies region-wise. This can apply to Sales, CTC, or any other currency-related data. You can record amounts in a customer’s local currency, while the CRM automatically converts them to your home currency

    • Better use of contacts

      Zoho inventory has the ability to add multiple contacts to customers. However Zoho inventory doesn't currently provide a way to link a contact to objects like sales orders. This means that while you can tell what company has placed a sales order you can't

    • How can we add products using a Wizard?

      We want to create a Wizard to add products. Why is there no possibility to use the products module when creating a wizard?

    • Orphan email alias blocking user creation – backend cleanup required

      Hello Zoho Mail Support, I´m unable to assign or create the address xx@iezzimatica.ar in my organization. Current situation: Alias cannot be assigned to any user (system says it is already in use) New user with this address cannot be created Address does

    • Ensure Consistent Service Delivery with Comprehensive Job Sheets

      We are elated to announce that one of the most requested features is now live: Job Sheets. They are customizable, reusable forms that serve as a checklist for the services that technicians need to carry out and as a tool for data collection. While on

    • Something wrong with client script??

      Someone have the same feeling? Client script behavior become very strange..

    • API 500 Error

      Hello amazing ZOHO Projects Community, I get this message. How can we solve this? { "error": { "status_code": "500", "method": "GET", "instance": "/api/v3/portal/2010147XXXX/projects/2679160000003XXXX/timesheet", "title": "INTERNAL_SERVER_ERROR", "error_type":

    • Polish signer experience to compete with docusign

      I would like to suggest that someone spend the little bit of time to polish the signer experience, and the email templates to more of a modern professional feel. They are currently very early 2000s and with some simple changes could vastly improve the

    • Next Page