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

      • Adding a Button in a Form in Zoho Creator App

        Hi I want to know how can I add a Button in Zoho Creator form. I have options that I select from a multiselect options and I want the button to add those selected options in a Subform. I do not want to add on a Page Builder I want it inside a specific

      • Internal Exception for Creator function

        I have been running a script successfully for several days using the scheduler in my application. Now today it suddenly creates and Internal Exception error. Nothing has changed about the script. The data is still retrievable from the web service it is using. Why would this suddenly be happening for no apparent reason? Also noticed that my usage logs are not up to date. Is something changing behind the scenes?

      • How to Set Up a Custom Domain and Customize Homepage

        Hello, I am experimenting with Zoho Creator to build applications for my own use case and have encountered a couple of issues: 1. Custom Domain Access: Is it possible to access my Zoho Creator application through a domain that I own? If so, how does the

      • Announcing new features in Trident for Mac (1.26.0)

        Hello everyone! Trident for macOS (v1.26.0) is here with new updates to securely manage your passwords, locally save your emails, and protect against emails with suspicious URLs. Let's take a quick look at them. Manage passwords with Zoho Vault eWidget.

      • Default Value on a Number

        Hi, I would be nice to also be able to set the Default Value for a Number Field, not just the Initial Value shown, so if not on the screen so not enetred it can have a value of 0 for example. Thanks Dan

      • Having trouble fetching contents of Zoho Connect Feeds using the API, requesting alternative API documentation.

        I'm trying to retrieve feed/post data from Zoho Connect using the API but facing challenges with the current documentation. What I've tried: OAuth authentication is working correctly (getting 200 OK responses) Tested multiple endpoints: /pulse/nativeapi/v2/feeds,

      • Tip#45: Custom Tags and Cluster Tags

        Tagging your work items helps categorize and label work items within your Zoho Sprints workspace. Now, this feature is expanded across multiple modules, along with the introduction of cluster tags that offer an advanced tagging mechanism. Manage Tags

      • Extensions 101 webinar series: Build, integrate, and monetize with extensions

        Attention developers! Are you ready to take your extension development skills to the next level? We're excited to bring back the Extensions 101 webinar series with an expanded lineup of Zoho products and an introduction to more platform features. Last

      • [Free Webinar] User Management in Zoho Creator - Creator Tech Connect

        Hello Everyone! We welcome you all to the upcoming free webinar on the Creator Tech Connect Series. The Creator Tech Connect series is a free monthly webinar that runs for around 45 minutes. It comprises technical sessions in which we delve deep into

      • A couple of minor enhancements to Workflows

        Last updated on September 17, 2024: These enhancements were initially available for early access, and we've now enabled them for all users. We are elated to announce a couple of enhancements to custom functions in our Workflows! Say hello to: "Source"

      • Business Continuity - Disaster Recovery

        I know about the Zoho CRM backup .zip files, however, this doesn't include any of the infrastructure with like custom fields or custom modules. I am curious on what everyone has in place for a true backup or what your plan is if your Zoho instance were

      • Narrative 11: Are your customers happy?

        Behind the scenes of a successful ticketing system: BTS Series Narrative 11: Are your customers happy? Happiness isn't just something you experience; it's something you remember. Hear your customers' voices by enabling customer happiness ratings in Zoho

      • Don't understand INVALID_REQUEST_METHOD when I try to post up an attachment

        When I make the POST request (using python requests.post() for files): https://www.zohoapis.com/crm/v8/Calls/***************01/Attachments I get this response: r:{ "code": "INVALID_REQUEST_METHOD", "details": {}, "message": "The http request method type

      • Signature field is showing black

        Hello, When customer signed the service form, it is showing as below picture Phone model: iPhone 16 Pro We tried delete and install application, but it not solved. This has on phone of a few person. There is any advice to solve this?

      • Zoho CRM Android app updates: record sharing, user image upload, Zoho Survey integration, and more

        Hello everyone, We've made some important improvements to Zoho CRM's Android app, and we'd like to walk you through the latest updates. Here's what's new: Record sharing with org users User image upload Zoho Survey integration support Venue preference

      • How to Delete/hide Google adwords section from Layout?

        Hi people, maybe someone can tell me how to remove or hide the Google adwords section from my layout? Im not using it and it takes too much space.

      • WIDGET in related record list ZOHO CRM; how to get and put data to subform custom fields?

        he need: Read and write two custom subform line-item fields on Quotes: Segment_wyceny (picklist/text) and W_pakiecie (number). Write works; read does not return these fields via SDK. Environment Zoho CRM Widget Zoho Embedded App SDK v1.2 Module: Quotes

      • Introducing Assemblies and Kits in Zoho Inventory

        Hello customers, We’re excited to share a major revamp to Zoho Inventory that brings both clarity and flexibility to your inventory management experience! Presenting Assemblies and Kits We’re thrilled to introduce Assemblies and Kits, which replaces the

      • Way to update CRM records in quik view

        I have custom module in zoho crm and that module have 500 records. I want a quick way or UI so that user can easily update the record information in quick view without going to record detail view or edit view. I tried zoho sheet option but in zoho sheet

      • Where to integrate Price Book and Product List Price

        Hello, We sync zoho crm all modules with all data to zoho analytics. In zoho crm, we have "Price Books" and "Products" modules, where each product is assigned to a few price books with different list prices. From zoho crm, I am able to export a dataset

      • Form / CRM Integration Not entering into workflow

        I have a simple form setup with company name, first name, last name and lead source. Each of the fields are mapped to CRM Leads module. When the form is submitted, the lead is populated properly. I also have a workflow created that when the lead source

      • Zoho Slowness - Workarounds

        Hi all, We've been having intermittent slowness and Zoho just asks for same stuff each time but never fix it. It usually just goes away on it's own after a couple weeks. Given that speed is a very important thing for companies to be able to keep up with

      • Don't understand why Forms Mobile Scan and Fill not working

        I have configure enabled mobile scan and fill, I have enabled QR and Bar code on two fields name and position, I have mapped seq 1 to Name and seq 2 to position, I have created a 2d QR code with the person names and position, seperated by a comma. When

      • Recurring Supervisor Rule Reminders for Open/In-Progress Tickets

        Hello Zoho Support Team, I would like to suggest a potential improvement regarding reminders for tickets and activities in Zoho Desk. Currently, it is possible to set reminders only once. In the Supervisor Rules section, it is possible to configure reminders

      • Template usage

        Hi, We are using some templates as a response to customer questions. Is it possible to analyze the usage of these templates? We want to know if the use of our templates has increased over time

      • Ticket Status Colors

        Can i change the colors of Ticket Status in the admin panel? Or even change the background of the entire cell of a Critical ticket? This way its easy for my agents to see a urgent ticket when it comes in. Right now everything is black text. Here Right

      • Sync Lookup Fields from Zoho CRM

        HI Team, I have synced a lookup field from my CRM data to Campaigns. When I view the synced data the field appears to display a Zoho CRM record ID rather than the text value. Is it possible to get the sync to import the text value rather than the CRM

      • New From Address cannot verify

        I have created a new From Address, which is the support@ address for my domain, that forwards to the default support mailbox. Presumably then, the verification email that is sent, should turn up as a ticket, but it does not. How can I verify my from address so that I can use my own domain?

      • How to update/remove file in zoho creator widgets using javascript API

        Hi Team, I have developed a widget which allows inserting and updating records I have file upload field with multiple file upload. Now while doing insert form record, I am using uploadFile API to upload files for that record. I am using updateRecord API

      • issue with image thumbnails not showing in Image Selector

        We have been using Zoho Campaigns for over a year, maybe close to two years, and this issue just started happening in the last month. I wanted to wait to see if it would resolve on it's own, and it doesn't seem to be. The thumbnail images for all new

      • Deluge Script for adding tag

        Trying to create a custom function where a tag is added to a record - but for the life of me, I cannot figure out how. Help please! Moderation Update: Adding the help doc and sample to add Tags to records via deluge here for everyone's benefit. tag1 =

      • Unlock your Zoho Vault with OneAuth, Windows Hello, TouchID, YubiKey, and many more!

        Hello everyone, We are thrilled to introduce one of the most highly requested features – the ability to unlock your Zoho Vault using various authenticators. The primary purpose of a password manager is to remember just one master password and securely

      • Creator roadmap for the rest of 2022

        Hi everyone, Hope you're all good! Thanks for continuing to make this community engaging and informative. Today we'd like to share with you our plans for the near future of Creator. We always strive to strike a good balance of features and enhancements

      • How can I get base64 string from filecontent in widget

        Hi, I have a react js widget which has the signature pad. Now, I am saving the signature in signature field in zoho creator form. If I open the edit report record in widget then I want to display the Signature back in signature field. I am using readFile

      • Add Setting Values to the Rules

        Hi, It would be great to use the rules to set values in fields for submission, such as if a Type is X then set the Field Y to 10. Thanks Dan

      • So we ran with it for the week

        In our company i bit the bullet and ran with FSM for a whole week. Service calls, deliveries and surveys. Covering about 30-120 miles a day to domestic properties. Loved the appointment list and satnav integration. Loved the timer to measure the appointments.

      • Is there a way to set Document Owner/Sender via the API

        When sending requests for zoho sign, it would seem zoho uses the id of the person that created the zoho api cred to determine the owner_id, is there a way to set a default for this?

      • What's New - September 2025 | Zoho Backstage

        September has been a different month for Zoho Backstage. Instead of rolling out a long list of new features, we focused on something just as important: Performance, reliability, and stability The event season is in full swing, and organizers are running

      • Prevent stripping of custom CSS when creating an email template?

        Anyone have a workaround for this? Zoho really needs to hire new designers - templates are terrible. A custom template has been created, but every time we try to use it, it strips out all the CSS from the head.  IE, we'll define the styles right in the <head> (simple example below) and everything gets stripped (initially, it saves fine, but when you browse away and come back to the template, all the custom css is removed). <style type="text/css"> .footerContent a{display:block !important;} </style>

      • Stock Quotes/Spreadsheet

        It would be nice if we could download security and mutual fund prices from Yahoo Finance (or?) in order to maintain an up to date investment portfolio on Zoho. Any chance?

      • Next Page