How to Filter a Lookup Field Based on Another Lookup in Dynamics 365

How to Filter a Lookup Field Based on Another Lookup in Dynamics 365

Introduction

In Microsoft Dynamics 365 CRM, lookup fields are commonly used to establish relationships between entities. However, there are situations where users should only see specific records in a lookup based on the value selected in another lookup field.

For example:

• Filter Contacts based on the selected Account.
• Filter Cities based on the selected Country.
• Filter Opportunities based on the selected Customer.
• Filter Projects based on the selected Client.

This can be achieved using JavaScript and the Dynamics 365 Xrm API. In this article, we'll learn how to filter a lookup field based on another lookup field in Dynamics 365.

Business Scenario

Parent Lookup: Account Lookup

Child Lookup: Contact Lookup

When a user selects an Account, the Contact lookup should only display contacts related to that Account.

Without Filtering

Users can see all Contacts.

With Filtering

Users only see Contacts associated with the selected Account.

This improves data quality and user experience.

Solution Overview

We'll use:

• JavaScript Web Resource
• addPreSearch()
• addCustomFilter()
• FetchXML Filter

The filtering process works as follows:

1. User selects an Account.
2. JavaScript retrieves the Account ID.
3. A custom filter is applied to the Contact lookup.
4. Only matching Contacts are displayed.

Step 1: Create a JavaScript Web Resource

new_FilterLookup.js

Step 2: Add the JavaScript Code

var FilterLookup = {

    filterContactLookup: function (executionContext) {

        var formContext = executionContext.getFormContext();

        var accountLookup = formContext.getAttribute("parentcustomerid");

        if (accountLookup != null && accountLookup.getValue() != null) {

            var accountId = accountLookup.getValue()[0].id.replace("{", "").replace("}", "");

            formContext.getControl("primarycontactid").addPreSearch(function () {

                var filterXml =
                    "<filter type='and'>" +
                    "<condition attribute='parentcustomerid' operator='eq' value='" + accountId + "' />" +
                    "</filter>";

                formContext.getControl("primarycontactid").addCustomFilter(filterXml, "contact");

            });
        }
    }
};

Step 3: Register the Function

Open the form and configure the following:

Form Properties

new_FilterLookup.js

OnChange Event

Field:

parentcustomerid

Function:

FilterLookup.filterContactLookup

Enable:

Pass execution context as first parameter

Step 4: Publish Changes

Save and publish all customizations.

How the Code Works

Get Selected Account

var accountId = accountLookup.getValue()[0].id;

Retrieves the selected Account record.

Register PreSearch Event

addPreSearch()

Executes before the lookup search opens.

Apply Custom Filter

addCustomFilter()

Adds a FetchXML filter to the lookup.

Filter Contacts

<condition attribute='parentcustomerid'
operator='eq'
value='ACCOUNTID' />

Only Contacts linked to the selected Account are displayed.

Example: Country and City Lookup

Suppose you have:

Country Lookup

new_country

City Lookup

new_city

Filter cities by selected country:

var filterXml =
"<filter type='and'>" +
"<condition attribute='new_country' operator='eq' value='" + countryId + "' />" +
"</filter>";

Result:

• India → Chennai, Hyderabad, Bangalore
• USA → New York, Chicago, Dallas

Users only see relevant cities.

Advanced Example Using FetchXML

var filterXml =
"<filter type='and'>" +
"<condition attribute='statecode' operator='eq' value='0' />" +
"<condition attribute='parentcustomerid' operator='eq' value='" + accountId + "' />" +
"</filter>";

This filters:

• Active Contacts only
• Related to selected Account

Best Practices

Use PreSearch Event

Always use addPreSearch() for lookup filtering.

Validate Null Values

Always check whether the parent lookup contains a value.

Use Entity Schema Names

Use schema names instead of display names.

Keep Filters Lightweight

Avoid large FetchXML queries that affect performance.

Test Security Roles

Verify users can access the records returned by the filter.

Common Use Cases

• Account → Contact
• Country → City
• Customer → Opportunity
• Department → Employee
• Project → Task

Troubleshooting

Lookup Not Filtering

• Verify JavaScript is loaded.
• Verify event registration is correct.
• Verify function name is correct.

No Records Displayed

• Verify relationship exists.
• Verify schema names are correct.
• Verify Account ID is being retrieved.

JavaScript Errors

Use browser Developer Tools (F12) to inspect console errors.

Conclusion

Filtering lookup fields based on another lookup field is a common Dynamics 365 requirement that improves data accuracy and user experience. Using JavaScript with addPreSearch() and addCustomFilter() allows you to dynamically control which records users can select.

Whether you're filtering Contacts by Account, Cities by Country, or Opportunities by Customer, this approach provides a clean and efficient solution within Dynamics 365.