How do I use entities that have a constructor predicate in TDX in LogiQL

Question

I want to convert an existing entity that uses a refmode into one that has a multidimensional constructor predicate. However, I am unsure of how to update a TDX service that creates those entities.

Attempting to use the service unchanged from when the entity used a refmode I get the following error when attempting to import data.

2015-11-25 09:15:45,00500+00:00 ERROR DelimTxn           - Error building database transaction for 358c49fb-2fd6-4433-8c56-c59196e0ffaf
<3>    Cannot bind entity without refmode directly to a column (try selecting a constructor).

What I need to know is how I go about "selecting a constructor" in the TDX config.

Answer 1

Unfortunately TDX still does not fully support constructors yet.

You can export and import data that contains entities created by constructors using functions, but it is currently not possible to create the entities themselves.

For example, if you have a file SKU|SALES and skus are created by sku_cons, you could use a predicate binding like this:

predicate_binding_by_name["sales"] =
    predicate_binding(_) {
      predicate_binding_columns[] = "SKU, SALES",
      column_binding_by_arg[0] =
        column_binding(_) {
          column_binding_function[] = "sku_cons"
        }
    }

If you have your entities already created, you can use this service to populate sales for those entities, and also to export the sales. But you cannot bind directly to the constructor nor use entity creation policies to make TDX automatically create new entities when importing sales. These features will come in a future release.