DocumentDB REST API: x-ms-documentdb-partitionkey is invalid

Question

I am attempted to get a Document from DocumentDB using the REST API. I am using a partitioned Collection and therefore need to add the "x-ms-documentdb-partitionkey" header. If I add this, I get "Partition key abc is invalid". I can't find anywhere in the documentation that expects the key to be in specific format, but simply supplying the expected string value does not work. Does anyone know the expected format?

Answer 1

Partition key must be specified as an array (with a single element). For example:

x-ms-documentdb-partitionkey: [ "abc" ]

Answer 2

Partition key for a partitioned collection is actually the path to a property in DocumentDB. Thus you would need to specify it in the following format:

/{path to property name} e.g. /department

From Partitioning and scaling in Azure DocumentDB:

You must pick a JSON property name that has a wide range of values and is likely to have evenly distributed access patterns. The partition key is specified as a JSON path, e.g. /department represents the property department.

More examples are listed in the link as well.