How to call an action with EntityCollection Input parameter Dynamics 365 WebApi

Follow my blog for more interesting topics on Dynamics 365, Portals and Power Platform. For training and consulting, write to us at info@xrmforyou.com
Xrm.WebApi methods introduced by Microsoft are great! But not much can be said about Xrm.WebApi.execute method which is used to invoke custom actions from client side code.
To be honest, ever since I have written blogs on Xrm.WebApi.execute like this one- https://debajmecrm.com/calling-bound-actions-entity-actions-using-xrm-webapi-execute-in-dynamics-v9/, I have been getting huge number of questions on how this topic.

And one of the question that is coming time and again is – How do I pass an input parameter of type EntityCollection. I was baffled a bit as to why this question has popped up time and again but when I really go and search the docs and community, I really find very little information on the same and this answers my curiosity. Well, I have decided to pen this down. Actually it’s pretty simple but in case you don’t know, it can cost you days.
So I created an Action with two input parameters – one with Type entity reference and the other of type Entity Collection. Screenshot for reference.

The entity reference is of type Account as well. And in the entity collection also we are going to pass a collection of accounts.
So here is the call to the action which would work just fine.
var request = {};
request.entity = { entityType: “account”, id: “475B158C-541C-E511-80D3-3863BB347BA8” };
request.EntRef = { “@account.id”: “475B158C-541C-E511-80D3-3863BB347BA7” };
request.EntColl = [
{
“@account.id”: “475B158C-541C-E511-80D3-3863BB347BA6”, “name”: “acc1”, “@odata.type”: “Microsoft.Dynamics.CRM.account”
}
,
{
“@account.id”: “475B158C-541C-E511-80D3-3863BB347BA5”, “name”: “acc2”, “@odata.type”: “Microsoft.Dynamics.CRM.account”
}
];
request.getMetadata = function () {
return {
boundParameter: “entity”,
operationType: 0,
operationName: “new_ActionProcess”,
parameterTypes: {
“entity”: { typeName: “mscrm.account”, structuralProperty: 5 },
“EntRef”: {
typeName: “mscrm.account”,
structuralProperty: 5
},
            “EntColl”: {
typeName: “Collection(mscrm.crmbaseentity)”,
structuralProperty: 4
}
}
};
};
Xrm.WebApi.execute(request).then(
function (result) {
debugger;
},
function (error) {
}
);
Highlighted the entity collection areas for easy readability.So as you can see, you need to pass the typeName as “Collection(mscrm.baseentity)”.
This is what we need to do. But the question is how did I find that I need to put this as the type name. After all this name is not something which can come out of intuition.

My suggestion here is, whenever you get stuck with names, fallback to the metadata.
I go to Settings –> Customizations – Developer Resources and download the OData Metadata. Once downloaded when I search for the action name this is what I find.

After that it’s just piece of cake.
Hope this helps and saves you some precious time.
-Debajit Dutta
(Dynamics MVP)
For consultation/ training visit www.xrmforyou.com or reach out to us at info@xrmforyou.com