How to Set Lookup Column Value in Microsoft Dataverse Connector in Cloud Flows

If you're using Microsoft Dataverse connector in your flow and getting the following errors, that means you are either

1. setting the GUID value directly or
2. not providing a correct plural version of entity logical name.

Empty segment encountered in request URL. Please make sure that a valid request URL is specified.

Resource not found for the segment xxxxx

In that case, you may see one of the errors above or below.

URL was not parsed due to an ODataUnrecognizedPathException. Resource not found for the segment provided in the URL

1. In Microsoft Dataverse (legacy) connector, you can just set the GUID value of the record to populate the lookup value of the column. For polymorphic lookups, you will have an additional Type dropdown column (e.g. Customer Type) to choose the entity type of the record that you are setting.

But in the new Microsoft Dataverse connector, you need to provide the type of entity even if the lookup is just normal lookup to a single entity. For polymorphic lookups, there will be multiple columns for each entity type (e.g. Customer (Accounts) and Customer (Contacts) ) and you need to fill up the correct entity type that you are trying to populate. (and you still need to provide the entity type). Imagine if you are creating one of the activity records (e.g. Task) in the environment with a lot of entities enabled for Activities, you will see a lot of Regarding (xxxxxx) columns in your flow step.


2. Don't be fooled by the plural display name of the entity which is shown beside the field label. The EntitySetName that you need to provide is case sensitive and you cannot use that plural display name (Contacts) or entity logical name (contact). As mentioned in Dynamics CRM Tip of the Day #1311, what you need to use is the plural version of the entity logical name (aka EntitySetName) followed by the GUID enclosed in parentheses. «EntitySetName»(«RecordGUID»)
e.g. contacts(«ContactID») which will be translated to something like

contacts(9b5d7915-a22a-41d4-ab95-e4fc2a5f80b3)

For out of the box entities, the EntitySetName is the same as the plural display name for most of them. But things get tricky when you are trying to populate the value for the custom entity. You may be able to add 's', 'es', 'ies', etc. but how the system defines the EntitySetName is not perfect for all scenarios. (e.g. the EntitySetName of my lzw_journey entity is lzw_journeies.) If the entity name ends with an S, the system adds 'es' at the end for the EntitySetName (e.g. the EntitySetName of lzw_tomateos entity is lzw_tomateoses.).

In order to get the so-called EntitySetName, you can get it from the table hub under Tools menu.

You can also search it from the API

[Organization URI]/api/data/v9.1
e.g. https://contoso.crm.dynamics.com/api/data/v9.1

or replace the «EntityLogicalName» in the following URL format to get it for a particular entity
[Organization URI]/api/data/v9.1/EntityDefinitions(LogicalName='«EntityLogicalName»')?$select=EntitySetName
e.g. https://contoso.crm.dynamics.com/api/data/v9.1/EntityDefinitions(LogicalName='contact')?$select=EntitySetName

Another easier way to get the EntitySetName is by using the Level up for Dynamics 365/Power Apps Chrome browser extension to open the Entity Metadata list view and search by the table name.

Another alternative is the Metadata Browser for Dynamics 365/Power Apps Chrome browser extension.

The EntitySetName and the brackets need to be set in the input of the column (as in the first image below). If you use Expression to set the field with EntitySetName (as in the 2nd image below), you will get the following error .

Unable to process template language expressions in action 'Step_name' inputs at line '0' and column '0': 'The template function 'xyz_entitysetname' is not defined or not valid.'.

UPDATE2: You can now set the null value to the lookup column by using the Microsoft Dataverse connector.

If you set the null value or the optional lookup value from another record which can potentially be empty in Microsoft Dataverse connector, you will get the following error.

An error occurred while validating input parameters: Microsoft.OData.ODataException: The 'odata.bind' instance or property annotation has a null value. In OData, the 'odata.bind' instance or property annotation must have a non-null string value.

The error message is the same as setting null for single-valued navigation property using Xrm.WebApi but I am not sure it is possible/necessary to use a DELETE request to remove a reference to an entity as mentioned in the Microsoft documentation.

There is a workaround for that issue and you can refer to it in my other blog post.

UPDATE: As one of the commenters, manish, suggested, setting NULL value of the single lookup column can be done in the same way as web API calls. All you need to do is to use HTTP Request with Azure AD and DELETE method.
Format of that is : /api/data/v9.1/incidents(GUID)/xxxx_InternalContactId/$ref
where xxxx_InternalContactId is the name of Navigation Property linked with InternalContact.

Or we can use the Unrelate records function too.

But it is not working for most of the scenarios that I encounter such as clearing multiple lookup fields in one API call (without multiple Unrelate/Delete records actions), or the most common issue for me is passing the GUID from another step which is an optional lookup field (so that the value may/may not be null)
While you're at here, please check out and vote for my submission at Power Automate Ideas regarding that.
https://powerusers.microsoft.com/t5/Power-Automate-Ideas/Allow-Setting-null-value-to-the-lookup-field-in-Common-Data/idi-p/427649