Resolve error on deep insert of navigation property Dynamics WebAPI - json

Question

I am using the Microsoft Dynamics Web API to write data to an entity in Microsoft Dynamics 365. When I try to do a deep insert I am receiving the error
An undeclared property 'ccseq_employeeid' which only has property annotations in the payload but no property value was found in the payload. In OData, only declared navigation properties and declared named streams can be represented as properties without values.
Why am I receiving this error and how can I resolve the error?
JSON
{
"ccseq_importdate" : "2017-05-28T04:00:00Z",
"ccseq_month" : "1",
"ccseq_year" : "2017",
"ccseq_name" : "Test",
"ccseq_status" : "100000000", "ccseq_ccseq_expensetransactionset_ccseq_expensetransaction_ExpenseTransactionSetID" :
[
{
"ccseq_employeeid#odata.bind": "/systemusers(6d2fd71b-32d1-dd11-a4f5-001a6449bbe7)",
"ccseq_clientid#odata.bind": "/ccseq_clients(663ebd00-73b9-4faf-90ed-f56bb9c2dc9b)",
"ccseq_navemployeeid" : "11111",
"ccseq_employeefirstname" : "John"
}
]
}
ExpenseTransactionSet is the parent of ExpenseTransaction meaning that ExpenseTransaction has a lookup to ExpenseTransactionSet. ccseq_ccseq_expensetransactionset_ccseq_expensetransaction_ExpenseTransactionSetID is one to many relationship. systemuser and ccseq_clients are separate entities that are lookups in ExpenseTransaction.
I've also tried the below variations on the "ccseq_employeeid#odata.bind"
objectid_systemuser#odata.bind
objectid_ccseq_employeeid#odata.bind
ccseq_employeeid#data.bind
ccseq_employeeid#odata.bind : systemusers()
ccseq_employeeid_systemusers#odata.bind
systemuserid_systemusers#odata.bind
I have seen this question and this question and tried the suggested resolutions without success.

Answer 1

I discovered the answer reading this thread. The correct syntax for a Navigation Property in a deep insert is to use the Child Entity Name followed by brackets with the field name. The json needs to be changed to the below
{
"ccseq_importdate" : "2017-05-28T04:00:00Z",
"ccseq_month" : "1",
"ccseq_year" : "2017",
"ccseq_name" : "Test",
"ccseq_status" : "100000000",
"ccseq_ccseq_expensetransactionset_ccseq_expensetransaction_ExpenseTransactionSetID" :
[
{
// Next two lines are changed
"ExpenseTransaction[ccseq_employeeid#odata.bind]": "/systemusers(6d2fd71b-32d1-dd11-a4f5-001a6449bbe7)",
"ExpenseTransaction[ccseq_clientid#odata.bind]": "/ccseq_clients(663ebd00-73b9-4faf-90ed-f56bb9c2dc9b)",
"ccseq_navemployeeid" : "11111",
"ccseq_employeefirstname" : "John"
}
]
}

Answer 2

In the metadata document {org-url}/api/data/v8.0/$metadata, can you check the element-type of the collection-valued navigation property ccseq_ccseq_expensetransactionset_ccseq_expensetransaction_ExpenseTransactionSetID?
Is it the same type which has ccseq_employeeid as its navigation property? If not, and the property ccseq_employeeid belongs to the derived type, you may need to annotate the navigation property object as below:
{
"ccseq_importdate" : "2017-05-28T04:00:00Z",
"ccseq_month" : "1",
"ccseq_year" : "2017",
"ccseq_name" : "Test",
"ccseq_status" : "100000000",
"ccseq_ccseq_expensetransactionset_ccseq_expensetransaction_ExpenseTransactionSetID" :
[
{
"#odata.type": "Microsoft.Dynamics.CRM.ccseq_navemployee",
"ccseq_employeeid#odata.bind": "/systemusers(6d2fd71b-32d1-dd11-a4f5-001a6449bbe7)",
"ccseq_clientid#odata.bind": "/ccseq_clients(663ebd00-73b9-4faf-90ed-f56bb9c2dc9b)",
"ccseq_navemployeeid" : "11111",
"ccseq_employeefirstname" : "John"
}
]
}