In an API feed, you can enter a reference with its internal _id formatted as a string.
For example, if a customer wants to select all the orders related to a sales order list, you can use the _id value as a filter.
The _id is internally assigned when a customer is created and cannot be assigned a fixed value. In this case, you need to do a query to get the _id of the customer. To do so, you can apply a filter on the known public customer _id. You can then use the value in the GraphQL selection query.
Most entities have at least one unique key called the natural key. This key is used to identify a record in a data entry flow and to identify references to other records in the referenced nodes. You can also use this type of key directly for references. Its syntax is a string value with a dash as a first character, followed by the natural key.
For example, if a customer with an ID equal to JOHNDOE has an internal _id equal to 3141592 on a given tenant, you can use either *#JOHNDOE or 31415926 as a key to reference the value.
A natural key can have several components. If this is the case, the different segments of the key value must be separated by |.
For example, an address associated with a customer has a second part, called _sortValue, that usually has numeric values starting at 10 and incrementing by 20. You can use this address to reference the first address associated with JOHNDOE either using its _id - for example, 271828 - or the natural key *#JOHNDOE|10.