Logic apps convert a particular key from JSON object array to delimited string - azure-logic-apps

Question

Here is my JSON object array:
{
"#odata.context": "https://graph.microsoft.com/v1.0/$metadata#directoryObjects",
"value": [
{
"#odata.type": "#microsoft.graph.user",
"id": "b3cbd395-dfba-4d36-b6e5-161bf00c26a1",
"businessPhones": [],
"displayName": "Joe Bloggs",
"givenName": null,
"jobTitle": null,
"mail": "joebloggs#domain.com",
"mobilePhone": null,
"officeLocation": null,
"preferredLanguage": null,
"surname": null,
"userPrincipalName": "joebloggs_domain.com#EXT##domain2.onmicrosoft.com"
},
{
"#odata.type": "#microsoft.graph.user",
"id": "b0b80e63-5be2-44c9-87b7-e6ec52432796",
"businessPhones": [],
"displayName": "John Doe",
"givenName": "John",
"jobTitle": null,
"mail": "johndoe#domain.com",
"mobilePhone": null,
"officeLocation": null,
"preferredLanguage": null,
"surname": "Doe",
"userPrincipalName": "johndoe_domain.com#EXT##domain2.onmicrosoft.com"
}
]
}
I want to extract the mail key of each array object into a string like below so that I can then send an email to them later.
joebloggs#domain.com;johndoe#domain.com
I tried join(body('Parse_JSON_owners')?['value']?['mail'], ';') but that gives error:
The template language expression 'join(body('Parse_JSON_owners')?['value']?['mail'], ';')' cannot be evaluated because property 'mail' cannot be selected. Array elements can only be selected using an integer index.

Answer 1

You can initialise a string variable and use Append to string variable inside a For-each loop.
RESULT:

Answer 2

You could use the Select Data operation
With this Action you can map your objects to a new array of objects.
Select your source object, in your case that would be body('Parse_JSON_owners')
In order to only get an array with value types, you can first click on the switch button at the right side of the action.
Add your property, in your case that would be item()?['value']?['mail'].
Result output
In a run this would result in an array with plain string values.
After this, you can join the array the way you already had in mind, with the join function. This would look something like this: join(body('Select'), ';')