Generate number sequence values from REST services and OData

One of the options to integrate MSDyn365FO with external systems is using the data entities with REST services and OData. To use OData the entity must have its IsPublic property set to Yes:

Otherwise, if it´s an standard entity, we´ll need to duplicate it because it´s not possible to change the property value in an extension.

If we´re doing an integration with an external system using OData to create new records in the ERP, we can have an issue when the record has a mandatory ID, as we can see in the Customers V3 entity. If we check the Mandatory property of the CustomerAccount field it´s set to Auto, getting the value from the CustTable where it´s set to Yes.

In this case, if we try to create a customer without an account number the service will fail as it can be seen in the Postman capture below:

Crystal clear error, the customer account field cannot be empty.

This isn´t happening with the Vendors entity. “Hey! But the vendor account is mandatory in the VendTable!” someone may think. Correct, it is, but not in the entity where it´s been overriden:

To see how the standard solves this we need to check the entity initValue method:

The skipNumberSequenceCheck is one of the data methods from the Common class, and it´s a relative of skipDataMethods, skipDataSourceValidateWrite, skipAosValidation, etc… It will always return false unless we tell it not to do so by passing true earlier in the code through the parameter.

The NumberSeqRecordFieldHandler class enableNumberSequenceControlForField will initialize the value of the field we pass in the parameters with the next value from the sequence we select. In this case it´s filling the vendor account field with the sequence set in the vendor parameters (obviously)

So, doing the same as the standard does, we’re going to extend the entity and the initValue method:

Having done this we’ll try again in Postman, this time deleting the CustomerAccount parameter from the body, and…

Success! We’ve got a new customer! Created from an external system and using the number sequence from Dynamics 365.

This is no mistery, it just mimicks what the standard does. As MSDyn365FO developers we must try to do that, always. Always… as long as we can, of course 🙂 Because even though partners always try to apply the standard as much as possible, we all know that in the end, there´ll be some customization done (hopefully, we´re developers!).