Metadata instance lookup

This guide describes how to use the Whistle function mde:lookupByKey in a Whistle script to look up a metadata instance object from a bucket.

Reference data lookup

Manufacturing Data Engine (MDE) provides a custom Whistle function to retrieve a metadata instance object from a metadata bucket by natural key. Metadata instances can be retrieved from any bucket, but the function is commonly used to look up reference data from a lookup bucket.

You can look up a metadata instance by its natural key by calling the mde:lookupByKey function in a Whistle script. The function takes the lookupbucket_name, natural_key and bucket_version of the instance as the arguments, and returns the latest metadata instance for the provided natural key. You can use the instance to populate fields in a proto record in the parser, like in the following example:

Caution: This example uses incomplete code for demonstration purposes and is not guaranteed to work.

"data" : {
  "complex" : {
    "VIN" : mde::lookupByKey("vin-lookup-bucket", input.vinKey, 1).VIN,
    "vin_registration_time" : mde::lookupByKey("vin-lookup-bucket", input.vinKey, 1).vin_registration_time,
    "ResultValue" : 163.0482614,
  }
}