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:


      • Recent Topics

      • Dark mode for Zoho Creator / Zoho CRM Code editor

        Hi Team, Is there any plans for Dark mode in Zoho creator / Zoho Crm code editor and development pages in pipeline?

      • Is there a way to make a button scroll down?

        Looking to have a button on a landing page scroll down to another section on the page. Any recomendations outside of coding?

      • ZOHO Android Client

        Hi, I installed the Android app, but it had an issue, so I reinstalled it. I was able to add multiple accounts, but now when I add the next account, it just duplicates the one I already have and will not even allow me to enter the info for another account.

      • I'd like to suggest a feature enhancement for SalesIQ that would greatly improve the user experience across different channels.

        Hello Zoho Team, Current Limitation: When I enable the pre-chat form under Brands > Flow Controls to collect the visitor’s name and email, it gets applied globally across all channels, including WhatsApp, Messenger, and Instagram. This doesn't quite align

      • Enhance Barcode/QR Code scanner with bulk scanning or continuously scanning

        Dear Zoho Creator, As we all know, after each scan, the scanning frame closes. Imagine having 100 items; we would need to tap 100 times and wait roughly 1 second each time for the scanning frame to reopen on mobile web. It's not just about wasting time;

      • Managing Rental Sales in Zoho Inventory

        I am aware that Zoho Inventory is not yet set up to handle rental sales and invoicing. Is anyone using it for rentals anyway? I'd like to hear about how others have found work arounds to manage inventory of rental equipment, rental payments, etc. Th

      • Zoho Flow to Creator 3001 Respoonse

        I have updated my Flows with the new V2 connection to Zoho Creator, but now some Flows do not work. They take in data from a Webhook and are supposed to create a record in Creator, however creator returns a 3001 message along with a failure, but I cannot

      • File Upload to Work Drive While Adding Records in Zoho Creator Application

        Hi I am trying to set a file attachment field in zoho creator form, to enable the user to upload a scanned document from their local pc. The file should be uploaded to zoho workdrive and not to the default zoho creator storage. The file link should be

      • Why not possible to generate?

        Using this https://desk.zoho.com/DeskAPIDocument#TicketCount#TicketCount_Getticketcountbyfield on my ZML script url :"https://desk.zoho.com/api/v1/ticketsCountByFieldValues?departmentId=XXXXXXXXXXX&accountId!=XXXXXXXXX&customField1=cf_country_1:XXXXXX&field=overDue"

      • email

        Hi My crm email is not working, can you check, I have zoho one account.

      • Need option to see Mass Emails & Cadences in Gmail Outbox OR a dedicated Zoho Outbox

        Hi everyone, Right now, when we send 1:1 emails from gmail (with gmail API connected to Zoho CRM), those emails appear both in gmail's sent folder and in Zoho CRM. That works well. But when we send Mass Emails or Cadence emails form Zoho CRM, they are

      • I can't found API for Sales Receipts

        Hello May you please help me to find an API document for Sales Receipts to get data and retrive a custom fields like Invoice and credit notes Regards

      • Kaizen #205 - Answering Your Questions | Managing Picklists and Enabling History Tracking via Zoho CRM APIs

        Hello everyone! Welcome back to another post in our Kaizen series. In this post, we will look at how you can manage picklist fields in Zoho CRM using APIs. This topic was raised as feedback to Kaizen #200, so we are taking it up here with more details.

      • Multiple Vendor SKUs

        One of the big concerns we have with ZOHO Inventory is lack of Vendor Skus like many other inventory software packages offer. Being able to have multiple vendor skus for the same product would be HUGE! It would populate the appropriate vendor Sku for

      • Internally created tickets

        Hi there When tickets are created internally on-behalf of customers - there is nothing to show that the ticket was created by an internal agent. This means, that it's easy for our agents to confuse tickets which were created by internal team members and

      • Automatically change website passwords

        Hi everyone, We just switched to a Professional package to also use the "Automatically change website passwords" function. But I cannot find anything about it, how to use it, anywhere. Does anyone know how I can use this function? Best, Caspar

      • Change Invoice Prices for an Effective Date

        Hi, It would be a really good feature to be able to change the prices on invoices/recurring invoices from an effective date in the event of price increases. For instance, I am in the process of increasing prices that will be effective from a specific

      • "Other Current Asset" accounts as "Paid Through" accounts in Expense

        It would be incredibly useful to be able to assign accounts of type Other Current Asset as Paid Through accounts in Expense. Currently, Other Current Liability are permitted as Paid Through Accounts. This makes sense, as Credit Cards are current liabilities.

      • Multi column open text questions that allows respondents to add rows for additional information

        I need to create a question that has 2 columns with open text, but I also need to allow respondents to click a "+" button, or something similar, so that they can add additional information if they choose to. I've tried using the Multiple Textboxes type

      • Bot Filtering & Apple Mail Privacy Protection Compliance in Zoho Campaigns

        Dear Campaigns Users, The wait is over! We’re excited to announce that the enhanced bot filtering feature is now live in Zoho Campaigns. This update brings greater accuracy to your email campaign reports by distinguishing real user engagement from automated

      • Découvrons les détails qui simplifient vos journées de travail avec Trident

        Nous nous installons dans des routines efficaces et rodées avec le temps. Chaque matin, nous ouvrons nos e-mails, passons aux messages, consultons notre agenda, puis attaquons nos tâches. Ce processus nous semble maîtrisé, mais est-il réellement optimisé

      • Issue with Purchase Rate Showing as “0” After Importing Items List

        Dear Zoho Books Support Team, Good day. I’m reaching out regarding an issue I’m facing while importing my items list into Zoho Books. Despite mapping all fields correctly and including the purchase price for each product in my Excel file, the Purchase

      • API for Task Entity in Zoho Books

        I’m working on automating task creation in Zoho Books via a custom button in the Bills Module. The goal is to create a task in the Tasks Module and assign it to the Finance Team, so they can track progress efficiently. While reviewing Zoho Books documentation,

      • create invoice in zoho books from the zoho forms

        Is there a native way to have create invoice in zoho books, when zoho form is completed?

      • Email undelivered

        GOod Day I am always receiving an uncategorized-bounce to my email. I am not sure why this is happening.

      • Add inventory_valuation_method to items endpooints

        To ensure consistent item creation it would be helpful to have the inventory_valuation_method (FIFO vs WAC) be able to be set at item creation or as an update (consistent with current behavior where it is not allowed for items with existing transactions)

      • Use Zoho to send sales receipts for Gocardless transactions

        I've been using gocardless for years and have d/d mandates set up on there. Each week we get bulk payments from customer d/d's. However, we need to send sales receipts to these customers. So I know I can sync mandates into Zoho, and then I can set up

      • Zoho - Gocardless sales receipts

        I've been using gocardless for years and have d/d mandates set up on there. Each week we get bulk payments from customer d/d's. However, we need to send sales receipts to these customers. So I know I can sync mandates into Zoho, and then I can set up

      • Introducing Rollup summary in Zoho CRM

        ------------------------------------------Moderated on 5th July'23---------------------------------------------- Rollup summary is now available for all organizations in all the DCs. Hello All, We hope you're well! We're here with an exciting update that

      • Introducing Connected Workflows in Zoho CRM for Everyone : Free Your Teams to Focus on What Matters

        Hello Everyone, We’re thrilled to introduce the next big evolution in Zoho CRM for Everyone -- Connected Workflows. This new feature builds on our commitment to deliver a CRM that’s truly inclusive, adaptable, and designed for consistent collaboration

      • Cooling-off Period Just Got Better: More Coverage, More Control

        We’ve enhanced the Cooling-off Period feature in Zoho Recruit to give you more control over repeat applications and referrals. This helps you maintain a cleaner, more efficient recruitment pipeline. With this enhancement, you can: Prevent duplicate candidate

      • Revenue Management: #7 Revenue Recognition in Construction & Real Estate Industry

        If you are in the construction or real estate business, you are used to long project timelines and progressive invoicing to keep up with your billing. But when does revenue get recognized? Will it happen when the contract gets signed? At different milestones

      • TikTok (and other social platform) Messages and comments of the past

        When I link a social channel, Zoho will show in "Inbox", "Messages" and "Contact" sections the interaction done in the past? (comment, messages...)

      • Restrict Employee mail deletion

        Dear Zoho, Is there a way where i can restrict my employees to delete any mails from their account

      • 554 5.1.8 Email Outgoing Blocked.

        Hi guys, I just singed up for mateusz.nowicki@zoho.com mail and I can't send any mails.. Why? Everytime I try to send something I got error like the one in the screenshot. Please, help me.

      • Zoho IP blocked by SpamHaus

        ERROR CODE :550 - 5.7.0 Your server IP address is in the SpamHaus SBL-XBL database, bye

      • File Upload in Creator's Subfrom

        Hello Sir/Madam, Here is a Problem......... Scenario: In CRM One Custom Module (Payments) have one File Upload Field now we have to Upload that File into Creator's Custom Form (Documents) have one Subform (Documents) in Document Upload Field using Deluge

      • Trigger workflow base on email clic

        Searching the help and forum, I see that there were workflow trigger rules based on email. But now, I can't find this type of trigger when I create a custom workflow. What I'm looking for would be to automate the sending of an email for a new prospect,

      • Bigin Form Acknowledgement

        How to troubleshoot and find out why form acknowledgement is not sending emails after form submission?

      • Zoho Mail POP & IMAP Server Details

        Hello all! We have been receiving a number of requests regarding the errors while configuring or using Zoho Mail account in POP/ IMAP clients. The server details vary based on your account type and the Datacenter in which your account is setup. Ensure

      • Next Page