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

    • How can we manage the tags in ticket

      Allowing agents to use Tags indiscriminately can cause havoc. We could not find tag management where 1. The admin can create Tags beforehand for use by Agents 2. Permission can be allocated which roles/profiles can use existing tags or add new tags 3.

    • Feed Notifications filter?

      I'd like to have filter settings for Feed Notifications just like we have for Personal Email. If someone dumps a bunch of files into a project, we get a notification for every file!

    • Custom fields and filters for Timesheet

      HI Zoho Projects team. IT would be great and useful if we can add custom fields to the Timesheet design And is needed more options for filtering the timesheet dashboard, like "Milestones" and task list asociated to the record. Thank you

    • How do I rename the dropdown that contains a form and a report?

      I want to rename this, but I can't find how

    • Filtering two fields

      Hoping somone can assist, i am trying to create a report to show values from two different fields. e.g I have Field 1 Field 2 In some records, fields 1 and 2 are both "yes"; in other records, only one of the fields has the value "yes". Can we generate

    • Unable to Convert Quote to Invoice – Integration Active but User Not Recognized

      I’m having trouble converting a Quote into an Invoice inside Zoho CRM, even though the Zoho Finance Suite integration is enabled (Invoices, Quotes, Products, and Customers are all checked), and my user is an Admin in both Zoho CRM and Zoho Books, using

    • Owner drawings

      I entered an owner’s drawing transaction in 2023 but it’s still appearing on 2024 books. Is that supposed to happen? Or should Is there an additional step? I prefer for this transaction not to appear.

    • Running Balance in Account Statement.

      Running balance should come by default in the accounting statements but in ZOHO we need to customize every time to get the running balance in accounting statement. I did not understand, when the bank account statement opened from Bank Menu can show the

    • Importing Invoices

      Dear Team I used the enclosed csv file to import some invoices and it worked fine. I had to delete the file and when I am trying to re-upload it, I am getting the error for invoice number and branch "Resource does not exit." I tried a number of different

    • Enhance "Send Cliq Notification" Action in Zoho Desk Workflows (and also add Happiness Rating Support)

      ello Zoho Desk Team, We hope you're doing well. We’d like to submit a feature request regarding the “Send Cliq Notification” action available in Zoho Desk workflows — specifically in workflows triggered by Happiness Ratings, but also relevant to all workflows

    • Treatment of Non-Refundable Income after cancelling an Invoice

      A customer made part payments of 30,000 for an invoice 0f 100,000, and then he is unable to pay up the remaining and has asked for a refund. As per company policy, he can only get 75% of the amount paid, which is 22,500. The remaining 7,500 is non-refundable

    • I need refund

      I have purchased the Zoho Book standard plan; I had the impression that I would get the purchase > Bill feature. After purchasing, I found that billing is not included in the Zoho standard plan. I immediately canceled the subscription. I love the product,

    • Handling identifiers during an import

      Importing your data When importing data into an application, it is crucial to prevent data loss or duplication. These types of errors can hinder the development of a clean and well-organised database, which is essential for effective data management and

    • Creating Deposit Invoices

      Hi, we are a company that does project based work with a request at the begining of each project for a deposit payment. At the moment we are creating invoices for the deposit and an invoice for the completion of the project, however they are completely

    • Marketer’s Space - WhatsApp Pricing Update: What Marketers Need to Know and Do

      Hello Marketers, Welcome back to Marketer’s Space! WhatsApp made changes to their pricing model on July 1, 2025, moving from conversation-based pricing to a per-message pricing model. This week’s post focuses on what these changes mean for your WhatsApp

    • It's time to say goodbye to Zoho Recruit for me.

      Hello, I have been a Zoho Recruit user since 2013. The tool has evolved, with a better UI, new features and so on. The pricing is still a great asset too. BUT, that being said, important features are not coming fast enough. I tried to share my point of

    • change subscription within customer portal

      Would be great for the customer to be able to change their own subscription (or restart existing one) within the customer portal. Also, would like to be able to have early termination fee on subscriptions if canceled early.

    • How to make the add-on optional at the time of subscription?

      The scenario is this, we have a service which has optional add-ons. Like the customer who purchased the subscription may or may not want to get the add-on. In our case if the customer choose the addon we have monetary benefit. In case the user does not

    • Unable to add attachments to knowledge base anymore

      I have been adding articles to knowledge base in Zoho Desk (as part of Zoho One). Today suddenly i found that I am unable to upload and attachments to the articles. I get the following error: "Attachment couldn't be added." I have uploaded the screenshot

    • Advanced factors for multiple scoring rules: Now with Zia scoring automations for all modules

      Greetings all, We're happy to offer improved scoring features by adding extra scoring factors, including Zia Scores, in our multiple scoring rules (MSR) feature. These new factors—which empower existing traditional scoring factors—include criteria for

    • Restrict Agents from Editing Shared Custom Views in Zoho Desk

      Hello Zoho Desk Team, We hope you're doing well. We’d like to submit a feature request regarding the custom views functionality in Zoho Desk. 🎯 Background We’re actively using custom views to filter and display tickets for different teams based on specific

    • Introduction Dario Schiraldi Deutsche Bank Executive

      Hello Everyone, Dario Schiraldi serves as a key leader at Deutsche Bank, where he plays a crucial role in shaping the bank's strategic direction and driving operational success. With a solid foundation in finance and leadership, Dario is committed to

    • Is Zoho Shifts included in the Zoho One plan?

      In case the answer is no: there's any plan to make it available via One? Thank you

    • Feature Request: API Access for Managing Deluge Functions (with OAuth & Change Tracking)

      Hi everyone, I wanted to share a thoughtful request that came in from one of our Zoho clients this week. I believe many of us as partners and developers might relate to it. “One quick item to flag: we’d love an official way to manage Deluge functions

    • Moving Subscriptions from one Customer to another

      We frequently need to move subscriptions from one Customer to another Customer in Zoho Billing and the only way we have figured out to do this is to cancel it in the old owner's profile and manually recreate in in the new owner's profile. In doing this,

    • how to add new line in Deluge?

      I want to make string with line separation like this: this is the first line second line third line I have tried to use \n <br> or </br> inside the string but I can't achieve the result like the example above. I want to create a task by using custom function

    • How to pause a subscription/recurring order ?

      Hello, I'm evaluating Zoho Subscriptions for a food co-op where members order a box of produce every week. The software that we're currently using allows members to set up a recurring order. Members can pause the recurring order when they don't want a box for a while and then resume it later. Is it possible to pause/resume a subscription ? Thanks John

    • Hosted Payment Pages - how to update the address in zoho billing

      I"m playing around with the muti-page hosted payment pages which have places for customers to enter their addresses when paying. Why does this not update their address in Zoho Billing after payment? What can I do to make this happen?

    • Tracking training certification expirations

      Hi Zoho Community! I'm looking for some input on the best and most efficient ways to track training expirations in Zoho CRM. I have a very specific workflow that I am looking for - my company offers trainings, and the certification expires every 2 to

    • Kaizen #164 : Client Credentials

      Hello everyone, Welcome back to Kaizen. In this post, we will discuss Client Credentials Flow and when it can be used. What is Client Credentials Flow? According to RFC6749, the official specification for the OAuth 2.0 authorization framework, "The client

    • CRM Email Template Align Left Instead of Center

      Is there a way to make a basic template align to the left instead of center? I know I'm likely forced to the 600px wide with the basic templates but I would REALLY like to set the email to the left instead of center. The basic templates make all the emails

    • Client Script - "Click' Button on Purchase Order - Specify "To Contact" or "To Supplier"

      The send email button is unique on the purchase order in that is has an additional submenu to send email "To Contact" or "To Supplier" It appears that the "click" event in Client script doesn't work correctly, probably because the button click didn't

    • Add Client Credentials Flow to Python SDK

      The Zoho CRM API supports a client credentials flow to automatically generate ephemeral access tokens, and this can be done programatically. The Python SDK however requires you to provide a grant token, refresh token, or access token when initializing

    • Conditional display of fields in Zoho Books Custom modules based on another field

      We're currently working with a Custom Module in Zoho Books and have a question about improving data entry efficiency and user experience. Our module includes a "Client Type" dropdown field, which determines the type of information to be collected. Each

    • Background Image for page in Zoho Creator

      Is it possible to use an image as the background in a page in Zoho Creator? I see it is possible to use an image as the background within a panel, but about about the page itself?

    • Zoho IP address blocked by Microsoft

      Today I tried to send emails to Outlook email addresses and all of them failed. The log displays like this: Reporting-MTA: dns; mx.zohomail.jp Arrival-Date: Fri, 27 Jun 2025 12:52:30 +0800 Original-Recipient: rfc822; ######@outlook.com Final-Recipient:

    • Request to Enable Full DNS Management Access for My Domain

      Hello Zoho Support Team, I have purchased the domain "digimarts365.online" through Zoho, and I need to add A and CNAME records to connect it with my Shopify store. However, DNS Toolkit is not allowing me to edit or add any records. Kindly enable full

    • Backup flow, see change log / history

      Hello, I would like to know, how flows can be saved, copied and tracked. If I work on a Flow with multiple other colleagues we need to see the Changes made by others. Is there a history, changelog or something else? Also we need to backup/import flows

    • Problème de validation du domaine spelam.ma

      Bonjour équipe Zoho, J’ai l’honneur de vous contacter car je rencontre un problème technique au niveau de la validation de mon compte ou de mon domaine spelam.ma. En effet, j’ai déjà acheté le domaine, mais la validation ne semble pas être correctement

    • Critical:- Eneble TDS filing for 26Q from the zoho book

      We currently extract TDS data from Zoho Books and manually input it into a separate TDS software to generate the FUV file and file returns. Previously, while using Tally, we benefited from an integrated feature that seamlessly recorded transactions and

    • Next Page