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 #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.

    • Kaizen #210 - Answering your Questions | Event Management System using ZDK CLI

      Hello Everyone, Welcome back to yet another post in the Kaizen Series! As you already may know, for the Kaizen #200 milestone, we asked for your feedback and many of you suggested topics for us to discuss. We have been writing on these topics over the

    • Recent Topics

    • Tip 19: How to display images in Pages using ZML snippets

      Hi folks, We're back with another tip on how to use Zoho Markup Language (ZML) to create interactive pages in Zoho Creator. You can use ZML snippets to add various kinds of components to your pages and structure them in meaningful ways. That's not all, though—using ZML you can ensure your application is automatically compatible with all kinds of devices without any inconsistencies. We often get questions from users about how to invoke Deluge scripts within ZML code. Here's a simple use case for adding

    • Can zoho swign format block text spacing automatically when prefilled from zoho crm?

      I'm sending zoho sign template from zoho crm, so that zoho crm pre-populates most fields. I have existing pdf documents that i am having signed. I have no ability to change the pdf documents, they are standardized government forms. The problem I am facing

    • Zoho Inventory / Finance Suite - Add feature to prevent duplicate values in Item Unit field

      I've noticed that a client has 2 values the same in the Unit field on edit/create Items. This surprised me as why would you have 2 units with the same name. Please consider adding a feature which prevents this as it seems to serve no purpose.

    • Reference lookup field values in Client script

      hello all, I'm using a "ZDK.Apps.CRM.Products.searchByCriteria" function call, which is returning the matching records correctly; however, one of the fields is a lookup field which I need the associated data. I believe there is a way to get this data

    • In App Auto Refresh/Update Features

      Hi,    I am trying to use Zoho Creator for Restaurant management. While using the android apps, I reliased the apps would not auto refresh if there is new entries i.e new kitchen order ticket (KOT) from other users.   The apps does received notification but would not auto refresh, users required to refresh the apps manually in order to see the new KOT in the apps.    I am wondering why this features is not implemented? Or is this feature being considered to be implemented in the future? With the

    • Every time an event is updated, all participants receive an update email. How can I deactivate this?

      Every time an event is updated in Zoho CRM (e.g. change description, link to Lead) every participant of this meeting gets an update email. Another customer noticed this problem years ago in the Japanese community: https://help.zoho.com/portal/ja/community/topic/any-time-an-event-is-updated-on-zohocrm-calendar-it-sends-multiple-invites-to-the-participants-how-do-i-stop-that-from-happening

    • How can I filter a field integration?

      Hi,  I have a field integration from CRM "Products" in a form, and I have three product Categories in CRM. I only need to see Products of a category. Thanks for you answers.

    • How to implement new online payment gateway?

      Hello, Can you tell me how to proceed to implement my local payment gateway? DIBS has an open avaiable API that should be easy to implement into ZOHO BOOKS. http://tech.dibspayment.com/dibs_payment_window

    • Zoho CRM - Portal Users Edit Their Own Account Information

      Hi Community, I'm working on a client portal and it seems like the only I can make the Account record editable to the Contact, is if I add another lookup on the Account to the Contact record. Am I missing something as the account already has a list of

    • Connecting Zoho Mail with Apollo.io

      Hi, I am trying to connect my Zoho Mail account with my Apollo.io account to start sending cold email for prospecting purposes. I have activated the IMAP setting but I am still unable to connect to the Apollo account. I am using my email credentials but

    • Where does this report come from in the Zoho One ecosystems?

      Is this directly from MA, Analytics or ??? ???

    • Contact's title in "Contact Role Mapping"

      When I'm creating a deal, I'd like to see the contacts title in the listing. Right now, I only see this: How can I get the contact's title in there?

    • Zoho CRM - Client Portal - Hide Notes Related List

      Hi Community, I'm building a customer portal and I can't find a way to hide the notes related list. I don't want the client to see the notes I have about them. Is there a way to do this as it is no bin/trash icon when I hover over.

    • "Pivot Table" Conditional Formatting

      Team, I there a way to use conditional formatting a "Pivot Table"  report? Thanks, Arron Blue Pumpkin Hosting | Solutions Made Simple

    • How many clients can be added to Zoho Practice?

      How many clients can be added to Zoho Practice without having their zoho app?

    • Stage History

      when viewing a ticket , and you look at stage history tab (kanban view) and look at the stage duration column in days, it shows the current stage of the ticket as " current stage ". Should it not rather show the amount of days it has been in that current

    • Automating Ticket Responses Using Zoho Desk's AI Features

      We’re looking to set up an automation within Zoho Desk that can analyze incoming emails or tickets and automatically respond with relevant knowledge base articles based on the content of the request. Could you please guide us on how to configure this

    • Optimising CRM-Projects workflows to manage requests, using Forms as an intermediary

      Is it possible to create a workflow between three apps with traceability between them all? We send information from Zoho CRM Deals over to Zoho Projects for project management and execution. We have used a lookup of sorts to create tasks in the past,

    • Service locations are tied to contacts?

      Trying the system out. And what I discovered is that it seems that the whole logic of the app is, I'd say, backwards. There is a Customer - a company. The company has contact persons and service locations can be associated with different contact persons.

    • Enhancements to Zoho Map integration tasks

      Hello everyone, We're excited to announce enhancements to the Zoho Map integration tasks in Deluge, which will boost its performance. This post will walk you through the upcoming changes, explain why we're making them, and detail the steps you need to

    • Bug in Total Hour Calculation in Regularization for past dates

      There is a bug in Zoho People Regularization For example today is the date is 10 if I choose a previous Date like 9 and add the Check in and Check out time The total hours aren't calculated properly, in the example the check in time is 10:40 AM check

    • Narrative 12: Sandbox - Testing without the risk

      Behind the scenes of a successful ticketing system: BTS Series Narrative 12: Sandbox - Testing without the risk What is a sandbox environment? A sandbox environment is a virtual playground that allows you to test freely and experiment with various elements

    • Announcing new features in Trident for Mac (1.27.0)

      Hello everyone! Trident for macOS (v1.27.0) is here with new features and enhancements to improve scheduling and managing your calendar events. Let's take a quick look at them. Stay aligned across time zones. Both the scheduled and original time zones

    • Slow uploads of large files

      I'm wanting to use Workdrive for transferring large images and video (we're talking things from 100MB-5GB). I'm running solo on a 500MBit/sec fiber connection. I'm getting upload speeds to Workdrive of no more than about 1-3Mbytes/sec when going through

    • Migrate Your Notes from OneNote to Zoho Notebook Today

      Greetings Notebook Users, We’re excited to introduce a powerful new feature that lets you migrate your notes from Microsoft OneNote to Zoho Notebook—making your transition faster and more seamless than ever. ✨ What’s New One-click migration: Easily import

    • need to upload from airtable to google drive

      I have a zapier zap that automates between airtable and google drive. When a customer uploads a new file into airtable via a client portal interface, zapier uploads that file into a folder linked to that customer's project record. I need to replicate

    • Can't delete functions that are associated with deleted workflow rules

      We have a handful of functions that were once associated with a workflow rule, but the rule has been deleted. The function still thinks it is associated so I can't assign it to a new rule. It is starting to get really messy because we have a list of functions

    • Default Sorting on Related Lists

      Is it possible to set the default sorting options on the related lists. For example on the Contact Details view I have related lists for activities, emails, products cases, notes etc... currently: Activities 'created date' newest first Emails - 'created

    • Credit Management: #1 Credit You Owe vs Credits Owed to the Business

      Think about the last time you ordered food online. You might have paid in advance through your card, but you received a $20 refund because your order got delayed or cancelled. In most apps, refunds don't go into the bank account directly; instead, they're

    • Tip #46- Turn Every Session into an Insight with Zoho Assist survey report- 'Insider Insights'

      Delivering exceptional remote support isn’t just about resolving issues, it’s about understanding how both customers and technicians experience each session. That’s where Survey Report in Zoho Assist come in. You can configure and customize survey questions

    • CRM/Bookings integration edits Contact names

      Hi there, I've installed the extension that connects Zoho CRM and Zoho Bookings. When we get a new appointment from Bookings from an existing Contact, that Contact's record shows this: First Name was updated from asd to blank value Last Name was updated

    • Domain Change

      “Please update my Email-in domain from @biginmail.biginmail.in to @biginmail.zoho.com. Messages to the .in domain are bouncing.”

    • Webhooks Limit Exceeded

      Today, I received an error message saying, 'Total number of Webhook call exceeded', but when I look at Manage > Billing, it doesn't look like any of my invokeURL calls are being logged. Following the advice from this thread: https://help.zoho.com/portal/en/community/topic/webhooks-daily-limits-in-zoho-creator

    • Auto select option in CRM after Zoho Form merge

      Hi, I have a dropdown field in Zoho CRM that is filled with a Zoho Form. The data is filled but not automatically shown. After selecting the right value in the dropdown the information a second field is shown. So the question is; how can I make the dropdown

    • Bring your CRM data straight into your presentations in Zoho Show

      Let's say you are working on a presentation about your team's sales pipeline for an upcoming strategy meeting. All the information you need about clients and leads is in Zoho CRM, but you end up copying details from the CRM into your slides, adjusting

    • Zoho People 2.0 Help Manual

      Hello All, Zoho People Help Documentation is now available at this link. Please go through and get in touch with us at support@zohopeople.com in case of any questions. Regards, Hemalatha Chandrasekaran | Zoho People

    • Introducing New APIs in Zoho Contracts

      We are excited to announce the release of new APIs in Zoho Contracts to help you automate and manage every stage of your contract lifecycle more efficiently. Here’s a quick overview of what’s new: 1. Complete Contract Draft You can use this API to complete

    • Vimeo

      For me Vimeo is the most important video social channel for media and filmmakers. Would others agree and like it added to Zoho Social.

    • Delete a department or category

      How do I delete a Department? Also, how do I delete a Category? This is pretty basic stuff here and it's impossible to find.

    • Organization Emails in Email History

      How can I make received Org Emails to show up here?

    • Next Page