In this Blog, we will learn how we can use fetchxml with link-entity in Web API.

What is Link-Entity

1. To combine data from different records in your query you need to use the <link-entity> element.

2. Each <link-entity> needs 3 key pieces of information:

2.a. The entity types to link to

2.b. The attribute in the main entity to join from

2.c. The attribute in the another entity to join to

NOTE: If you have a many-to-many (N:N) relationship you can’t join the entities directly, you have to join via the intermediate “intersect” entity.

3. There are two types of link-types: inner and outer.

4. The Link-Entity syntax requires providing of an Alias using which the values of the attributes can be accessed from the result-set.

NOTE:  If you do not provide an alias, the platform will auto generate the alias for you.

Example:

Suppose we have a requirement in which we need contact details like fullname, firstname, lastname and the account details like name and phone number that is related to contact.

Solution:

1. First, we will write a simple FetchXml query for contact in which we will select the attributes like fullname, firstname, lastname.

API Request:

https://dev-onepiece07.api.crm7.dynamics.com/api/data/v9.2/contacts?fetchXml=<fetch> <entity name="contact"> <attribute name="fullname" /> <attribute name="lastname" /> <attribute name="firstname" /> </entity></fetch>

Output:

2. As per the requirement that has been mentioned in the example, we will add the link- entity to get the account and its details like name and phone number that are related to contact.

2.a. We will use an inner link-type which will match the data of both the entity, and it will give the result.

API Request:

https://dev-onepiece07.api.crm7.dynamics.com/api/data/v9.2/contacts?fetchXml=<fetch> <entity name="contact"> <attribute name="fullname" /> <attribute name="lastname" /> <attribute name="firstname" /> <filter> <condition attribute="statecode" operator="eq" value="0" /> </filter> <link-entity name="account" from="accountid" to="parentcustomerid" link-type="inner" alias="account"> <attribute name="name" /> <attribute name="telephone1" /> </link-entity> </entity></fetch>

Output:

2.b. We will use an outer link-type which will give all the data of the first entity if there are no matching records.

API Request

https://dev-onepiece07.api.crm7.dynamics.com/api/data/v9.2/contacts?fetchXml=<fetch> <entity name="contact"> <attribute name="fullname" /> <attribute name="lastname" /> <attribute name="firstname" /> <filter> <condition attribute="statecode" operator="eq" value="0" /> </filter> <link-entity name="account" from="accountid" to="parentcustomerid" link-type="outer" alias="account"> <attribute name="name" /> <attribute name="telephone1" /> </link-entity> </entity></fetch>

Output:

NOTE: Each query can contain a maximum of 10 links

We have used the link-entity to fetch all contact details like fullname, firstname, lastname and the account details like name and phone number that is related to contact.

Related blog links of Web API:

Set up a Postman Environment and Application User for Dynamics 365 CE – Nebulaa IT Solutions,

Filter in expand query of OData (D365 CE) – Nebulaa IT Solutions,

Batch Request to Create, Update and Delete records in Dynamics 365 CE – Nebulaa IT Solutions,

Create Notes with Attachment using Web API in Dynamics 365 – Nebulaa IT Solutions,

Create Parent – Child Record in Single D365 Web API Request – Nebulaa IT Solutions,

Use postman to Create record in Dynamics with the Web API – Nebulaa IT Solutions