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

    • Delay in rendering Zoho Recruit - Careers in the ZappyWorks

      I click on the Careers link (https://zappyworks.zohorecruit.com/jobs/Careers) on the ZappyWorks website expecting to see the job openings. The site redirects me to Zoho Recruit, but after the redirect, the page just stays blank for several seconds. I'm

    • How to add interviews through API

      I'm trying to add an interview without much luck. The documentation gives examples of adding just about everything except an interview. However, the issue might be the way I'm formatting it, because the documentation is unclear to me. It seems as if the xml should be passed in the url, which seems unusual. I've tried the data as both plain and character escaped, but nothing seems to work, nor do I even get an error response. https://recruit.zoho.com/recruit/private/xml/Interviews/addRecords?authtoken=***&scope=recruitapi&version=2&xmlData=<Interviews> <row

    • Connection to other user

      Zoho Cliq handles sharing of Custom OAuth Connections that require individual user logins.

    • How to invite friends on other social media platforms to one of my group chats in arattai?

      Hello, I have formed chat groups in arattai. I want to invite my friends on other social media platforms like WhatsApp/ FB to one of my groups. Different friends would be invited to different groups. How to share an invite link of one of my groups to

    • Cliq does not sync messages after Sleep on Mac

      I'm using the mac app of Cliq. When I open my mac after it was in sleep mode, Cliq does not sync the messages that I received. I always have to reload using cmd + R, which is not what I want when using a chat application.

    • Facing Issues with Sites Mobile font sizes

      my page renediaz.com is facing issues mobile view, when i try to lower font sizes in home page, instead of changing the size, it changes the line space

    • Search not working!

      I have items in my notebook tagged but when I search for a tag nothing comes up! Any fix for this?

    • Set expiration date on document and send reminder

      We have many company documents( for example business registration), work VISA documents. It will be nice if we can set a expiry date and set reminders ( for example 90 days, 60 days, 30 days etc.,) Does Zoho workdrive provide that option?

    • Analytics : How to share to an external client ?

      We have a use case where a client wants a portal so that several of his users can view dashboards that we have created for them in Zoho Analytics. They are not part of our company or Zoho One account. The clients want the ability to have user specific,

    • Automatically Update Form Attachment Service with Newly added Fields

      Hi, When I have a Form Setup and connected to a 3rd Party Service such as OneDrive for Form Attachments, when I later add a new Upload Field I have to remove and redo the entire 3rd Party Setup from scratch. This needs to be improved, such as when new

    • Payroll and BAS ( Australian tax report format )

      Hello , I am evaluating Zoho Books and I find the interface very intuitive and straight forward. My company is currently using Quickbooks Premier the Australian version. Before we can consider moving the service we would need to have the following addressed : 1.Payroll 2.BAS ( business activity statement ) for tax purposes 3.Some form of local backup and possible export of data to a widely accepted format. Regards Codrin Mitin

    • Zoho Desk API - Send Reply to CUSTOMERPORTAL

      Hello! I'll try to send a reply to Customer Portal, But the response is 500 (INTERNAL_SERVER_ERROR in service response). {"Error":"{\"errorCode\":\"INTERNAL_SERVER_ERROR\",\"message\":\"An internal server error occurred while performing this operation.\"}"}

    • Python - code studio

      Hi, I see the code studio is "coming soon". We have some files that will require some more complex transformation, is this feature far off? It appears to have been released in Zoho Analytics already

    • Best practices for managing Project Charters, Business Case and RAID logs within Zoho?

      Hello everyone, I’m currently refining our PMO setup within Zoho Projects and I’m curious how others are handling high-level governance documentation. We’ve been using the standardized Project Charter, Business Case and RAID frameworks from projectmanagertemplate.com

    • Zoho Books Payroll

      How am I supposed to do payroll and pay my employees with Zoho Books? I think it's pretty strange that an accounting software doesn't have the ability to perform one of the most common functions in business; paying your employees. Am I missing something,

    • Sort Legend & stacked bar chart by value

      I'd love to see an option added to sort the legend of graphs by the value that is being represented. This way the items with the largest value in the graph are displayed top down in the legend. For example, let's say I have a large sales team and I create

    • Is It Possible to Convert a Custom Module to a Quote?

      I recently created a custom module in our CRM environment for RFQs so that our sales team can submit quote requests directly in Zoho rather than by email/phone. This allows for a cleaner overall process, minimizing potential errors and potentially encouraging

    • Proposal: Actionable API Error Messages to Reduce Support Ticket Volume

      I've encountered a long-standing frustration with how Zoho Creator's API communicates errors to developers, and I'm hoping the Zoho team can address this in a future update. This issue has persisted for over 9 years based on community discussions, and

    • Dynamic Field Folders in OneDrive

      Hi, With the 2 options today we have either a Dynamic Parent Folder and lots of attachments all in that one folder with only the ability to set the file name (Which is also not incremented so if I upload 5 photos to one field they are all named the same

    • File Conversion from PDF to JPG/PNG

      Hi, I have a question did  anyone every tried using custom function to convert a PDF file to JPG/PNG format? Any possibility by using the custom function to achieve this within zoho apps.  I do know there are many third parties API provide this with

    • Allocating inventory to specific SO's

      Is there a way that allocate inventory to a specific sales order? For example, let's say we have 90 items in stock. Customer 1 orders 100 items. This allocates all 90 items to their order, and they have a back order for the remaining 10 items which could

    • Cliq iOS can't see shared screen

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

    • Pull cells from one sheet onto another

      Hello all! I have created an ingredients database where i have pricing and information and i want to pull from that database into a recipe calculator. I want it to pull based on what ingredient I choose. The ingredients database has an idea and i want

    • Closing the Loop: Why Lookup Asymmetry is Harming Data Integrity in Creator

      TL;DR: Lookup fields allow users to add new related records inline via the "+" icon, but there's no equivalent ability to edit an existing related record without navigating away and losing form context. Adding a native "Edit" icon—with automatic User

    • Add the ability to Hide Pages in Page Rules

      Hi, We have Field Rules to show and hide fields and we have page Rules, but we can't hide a page in Page Rules so it isn't completed before the previous page (And then have the Deny Rules to prevent submitting without both pages completed), we can only

    • Enable Free External Collaboration on Notecards in Zoho Notebook

      Hi Zoho Notebook Team, I would like to suggest a feature enhancement regarding external collaboration in Zoho Notebook. Currently, we can share notes with external users, and they are able to view the content without any issue. However, when these external

    • using the Client script on the load of the form if service no is empty means then i want to make issue relate to is Service

      using the Client script on the load of the form if service no is empty means then i want to make issue relate to field is Service if Purchae no is empty means then i want to make issue relate to is Purchase

    • Changes to the send mail Deluge task in Zoho CRM

      Hello everyone, At Zoho, we continuously enhance our security measures to ensure a safer experience for all users. As part of our ongoing security enhancements, we're making an important update on using the send mail Deluge task in Zoho CRM. What's changing?

    • Work Order wont mark as Completed

      I have a couple of work orders that won't mark as completed even when I've marked the Service Appointments as completed fully.

    • Item name special charaters <>

      Im trying to input speical characters such as < and > into item name and item description but comes up with following error: Invalid value passed for Item Name and Invalid value passed for Item Description How do i allow speical characters?

    • Zoho Analytics Dashboard - How to hide the user filter

      I am using the same dashboard template across different external clients and applying a user filter to the data by site URL. How can I hide the user filter in View Mode so the external client won't see the list of other clients in the drop-down menu?

    • Customer Parent Account or Sub-Customer Account

      Some of clients as they have 50 to 300 branches, they required separate account statement with outlet name and number; which means we have to open new account for each branch individually. However, the main issue is that, when they make a payment, they

    • Kaizen #229: Email-Deal Associations in Zoho CRM

      Hi All, Welcome back to another week of Kaizen! Emails are a core channel for customer communication in any CRM system. In Zoho CRM, emails can be associated with records across multiple modules. In this post, we will focus on email associations with

    • Action Required: Update Microsoft SQL Server Security Settings Before February 2026

      Dear Users, We recently deployed security updates in Zoho Analytics that inadvertently caused connection failures for a few customers using Microsoft (MS) SQL Server hosted on older Windows versions (Windows Server 2012, 2012 R2, and 2014). To restore

    • Contacts limit in basic vs standard - what counts? Are customers contacts?

      I’ve been using books for a number years for my small business. I only ever work with 20 clients at any given time. I do purchase services from a number of vendors to run my business, so there are some comtacts there too. I used to use the basic package,

    • Saving issue

      First problem I opened a MS word file in writer. after the work is done, it does not save instantly, I waited for like 10min and it still did not save. second problem When I save a file, then file gets saved as another copy. I just did save, not save

    • 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

    • Create Tasklist with Tasklist Template using API v3

      In the old API, we could mention the parameter 'task_template_id' when creating a tasklist via API to apply a tasklist template: https://www.zoho.com/projects/help/rest-api/tasklists-api.html#create-tasklist In API v3 there does not seem to be a way to

    • Ability to Set a Unified Tab Order/View for All Users in Zoho Projects

      Hello Zoho Projects Team, We hope you are doing well. We would like to submit a feature request regarding tab/menu organization in Zoho Projects. Current Behavior: The tab (module) order in Zoho Projects is user-specific. Each user (internal or external)

    • Task Order

      Hello! I've recently switched to Zoho Projects and a long time user of MS Project, Asana and LiquidPlanner (which has recently been purchased) and I'm running into a frustration I'm hoping someone can assist with. It has to do with how tasks are ordered

    • Next Page