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

      • Documents unable view and need to downlad

        I can't view .doc files in Zoho mail unless I download them, but I can view PDF files without downloading.

      • we encountered a problem while sending your email. please try again later.

      • Adding and removing people from groups

        We're having problems adding people to a group. Apparently Zoho has one email address and will not recognize a different email address.

      • MAIL SEARCH IS NOT WORKING

        THIS ISSUE HAS BEEN BUGGING ME SINCE MORNING, PLEASE RESOLVE THIS AT THE EARLIEST

      • URL Parameter on Help Center SIgn in link

        Is it possible to add a url parameter to the sign in link on the Help Center?

      • migrating from HelpScout

        I am attempting to import a conversation file from helpscout into desk and am receiving size errors. What is the current file size restriction. Does anyone have any tips for a successful migration?

      • Layout Rules Don't Apply To Blueprints

        Hi Zoho the conditional layout rules for fields and making fields required don't work well with with Blueprints if those same fields are called DURING a Blueprint. Example. I have field A that is used in layout rule. If value of field A is "1" it is supposed to show and make required field B. If the value to field A is "2" it is supposed to show and make required field C. Now I have a Blueprint that says when last stage moves to "Closed," during the transition, the agent must fill out field A. Now

      • Article Name Sorting in Zoho Desk Knowledge Base (agent / admin side)

        Dear Zoho Desk Support, We are writing to request an enhancement to the Knowledge Base management feature within Zoho Desk. Currently, there is no option to sort articles by their name, which significantly hinders efficient article management, especially

      • How to parse JSON data with SQL in Zoho Analytics?

        Hi all, I have a column with JSON data. I want to show this column in a chart, but it is very messy, and no JSON parsing function is supported on Zoho Analytics. data example: {"id": 5, "status": "false", "date": "15/10/22"} what I want to do in SQL is

      • Add an Equation Field (Or update the Formula Field)

        Hi, I would like to be able to have one field as a Text Field with QR Code, and then have multiple Equation/Formula Fields that then take parts of that fields data with LEFT, MID, RIGHT, REGEX, etc. Thanks Dan

      • How to parse column having JSON data using SQL?

        We have a daily sync from a PostgreSQL database that brings data into Zoho Analytics. Some of the columns store raw JSON data. We need to build SQL queries on top to parse data from JSON and store them in discrete columns. There is no option for "Data

      • Enable report button based on the current user role

        Greetings  i have a report that contains action buttons, i want these buttons to appear as enabled only when the current logged in user has a certain role, for example only CEO role users will be able to use this button. but when setting the conditions

      • 500 Internal Error In Mail API

        I'm getting 500 Internal Error when using mail API. I'm getting this error for this one account, it works fine for other Account IDs which I have in my system.

      • Zoho live chat widget in React Js

        I am trying to test Zoho live chat widget code in react js, below is the sample code void(0)} onClick={()=>window.$zoho.salesiq.floatwindow.visible("show")}>LIVE CHAT window.$zoho = window.$zoho || {};window.$zoho.salesiq = window.$zoho.salesiq

      • Are there any plans to add Triggers for Subform edits?

        By The Grace of G-D.  Hi, How are you? Can you tell me if you have any plans to support subform edit as a workflow trigger? And what about have them trigger an "onChange" client script?

      • Zoho commerce

        i am facing issue with order summary emails.i am getting 1 continuous email for order received yesterday and today.ideally 1 email should be received for a particular date ie for 02/08 i should received 1 email from 12.01am till 11.59pm but it is being

      • Feature Request: Improve Category Page Sorting for "Out of Stock" Products

        Hi there, I'm writing to request a new feature that I believe would significantly improve the user experience in my online store. Currently, on category pages, products are sorted by popularity. However, when a popular product goes "Out of Stock," it

      • POSTMAN - There was an error in evaluating the Pre-request Script:Error: Cannot read properties of undefined (reading 'json')

        I am beginning the journey to learn how to use the API for Zoho Sign. I am getting the following error when I try to use postman. To walk you through how I am getting this error... I wanted to start with a simple GET and expand my learning from there.

      • How do i integrate shipstation with zoho inventory

        Wanting to set up my own delivery driver in ship station so we can get real time tracking of where the package is but then i want it to automatically update zoho inventory packages/shipments how can i do this

      • Invalid value passed for salesorder_id

        Hi, I am using sales return API, details are given below: API: https://inventory.zoho.com/api/v1/salesreturns?organization_id=700571811 Post Json Data: { "salesreturn_number": "", "date": "2020-11-12", "reason": "Testing from API", "line_items": [ { "item_id":

      • Create Invoice and Invoice Items from Sales Order via API

        Currently, when creating an Invoice associated with a Sales Order via the API, it appears that I must manually include all of the items (line_items) even though they are already part of the Sales Order. My question is this: is it possible to raise an Invoice via the API based on all of the information associated with a Sales Order--such as the  items? In other words, do I always have to manually include the items (line_items) when raising an Invoice via the API when the Invoice is associated with

      • Outlook 2013 Calendar Syncs but "Related To" Field in Zoho is blank

        Outlook 2013 Calendar Syncs but Related To Field in Zoho is blank I expect the "Realted To" field to be populated with the calendar participants

      • Export a Course

        Is it possible to export a course from Zoho Learn to a SCORM file?

      • Add and Remove Agents from Departments and Groups in Zoho One

        Hi Zoho Flow Team, We hope you're doing well. Currently, Zoho Flow provides an action to add an agent to a group in zoho one, but there is no action to remove an agent from a group or a department. Another action that we find missing is the option to

      • Zoho learn Custom portal - networkurl & CustomPortalId

        I want to get my individual account’s networkurl and customportalId to use in this API: https://learn.zoho.com/learn/api/v1/portal/<networkurl>/customportal/<customportalId>/manual How can I retrieve the networkurl and customportalId using the API? I

      • Consumer Financing

        Does Zoho currently have a payment gateway (such as Stripe, Square, etc) which offers financing for customers? So, let's say the estimate we give the customer is greater than what they can afford at the time, but we can sell the service now, letting them

      • Intégration de la gestion des Passkeys dans Zoho Vault

        Zoho Vault est depuis plus d’une décennie une solution fiable pour les entreprises : pour la gestion, le partage et le stockage des mots de passe. En 2018, nous avons fait un pas en avant en proposant la connexion unique (SSO). Nous sommes fiers de franchir

      • Scan & Fill with double quote key/value pairs

        Hi, An old Ticket moved to a Topic/Idea: I love the idea of the new Scan & Fill as it nearly covers my previous request for a QR Scanner to read a multi-part QR Code. My QR Codes are hard-coded as below: {"key1":"value1","key2":"value2","key3":"value3"}

      • Analytics SQL Queries should allow # as comment

        # and // are very common for commenting in SQL. Not sure why analytics only allows /* and */ for commenting. Especially when # grays the line as if it's being commented out. This should be added for sure.

      • SalesIQ Operator Activity Reports in Zoho Analytics

        I'm busy building a dashboard in Zoho Analytics and I want to include SalesIQ stats in the dashboard, but I'm unable to get the statistics mentioned in the attached image. Any idea where I can get the stats for Operator Activity?

      • No longer can indent

        Hey there! Is it just me or were we used to be allowed to used tab or indent when writing. It’s not working right now, has this always been the case?

      • Free webinar alert! Seamless Transition with Lossless Migration: Zoho One + Zoho Mail

        Hello Zoho Mail Community! 🚀 Attention IT Admins and Email Administrators! Are you planning to migrate your organization's email to Zoho Mail within the Zoho One ecosystem? 📧 Join our exclusive webinar, Seamless Transition with Lossless Migration: Zoho

      • Add Resource to Export

        The Export Data feature does not include a column for the Resource field. Without this column, Zoho Bookings cannot be used by any business for resource-based services or event types e.g. room bookings, equipment bookings. It seems to be an oversight,

      • Client Script | Update - Client Script Support For Custom Buttons

        Hello everyone! We are excited to announce one of the most requested features - Client Script support for Custom Buttons. This enhancement lets you run custom logic on button actions, giving you greater flexibility and control over your user interactions.

      • Mandatory field via deluge code

        I would like to ask you if it is possible to make a field mandatory via deluge script. For example, if I have a decision box and I click on it then I want a single line field to be mandatory. If uncheck the decision box then to do the single line as optional. I think it is not possible to do that and I have to do it via validation in 'on validate' field. 

      • Revenue Management: #1 What does it mean to "recognize" revenue?

        Earning revenue isn't just about collecting cash from your customers. It's about recording the income correctly and consistently. Revenue recognition is the process of deciding when and how to record revenue in financial statements so that they reflect

      • Power of Automation :: Auto-Populate Integration Field in Projects with CRM Account Data

        Hello Everyone, A custom function is a software code that can be used to automate a process and this allows you to automate a notification, call a webhook, or perform logic immediately after a workflow rule is triggered. This feature helps to automate

      • Zoho Forms and ChatGPT - populating a field using AI.

        I have a form where I would like the user to enter a response or query, and have another field populated using AI. For example, user enters Field 1, AI populates Field 2 in response. I want to be able to wrap some additional instruction text around the

      • campo tag para api

        debo conectarme a una api de zoho inventory y ocupo tomar el campo tag para poder asi jalar el articulo que cuente con el campo correcto en tag ejemplo que tag existen carro y avion que cuando busque los articulo con tag carro arroje solo estos por mas

      • Uploading file as attachment to Zoho CRM

               Hi,   I am trying to attach a file to a Zoho CRM contact using Zoho Flow. Right now, I try to do it through the “Upload File” field in Zoho CRM (In my screenshots, it’s called Téléchargement du fichier 1).   Here is what I tried:   Case 1: Webmerge document The Flow is called “Custom Function” (see screenshot 101).   Step  1: Creating a Webmerge document (screenshot 99)   Step 2: I use “Update module entry” to upload the created file. I upload Webmerge’s “Document” in my “Téléchargemet du

      • Next Page