Adds a ObjectFieldLookup that facilitates lookup of fields for Retrie…

…vables that are in on 'object' relation to the core retrievable.

vitrivr-engine-query/src/main/kotlin/org/vitrivr/engine/query/transform/FieldLookup.kt → vitrivr-engine-query/src/main/kotlin/org/vitrivr/engine/query/transform/lookup/FieldLookup.kt

@@ -1,4 +1,4 @@
-package org.vitrivr.engine.query.transform
+package org.vitrivr.engine.query.transform.lookup
 
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.flow.Flow

vitrivr-engine-query/src/main/kotlin/org/vitrivr/engine/query/transform/FieldLookupFactory.kt → vitrivr-engine-query/src/main/kotlin/org/vitrivr/engine/query/transform/lookup/FieldLookupFactory.kt

@@ -1,4 +1,4 @@
-package org.vitrivr.engine.query.transform
+package org.vitrivr.engine.query.transform.lookup
 
 import org.vitrivr.engine.core.model.metamodel.Schema
 import org.vitrivr.engine.core.model.retrievable.Retrieved

vitrivr-engine-query/src/main/kotlin/org/vitrivr/engine/query/transform/lookup/ObjectFieldLookup.kt

@@ -0,0 +1,50 @@
+package org.vitrivr.engine.query.transform.lookup
+
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.flow
+import kotlinx.coroutines.flow.toList
+import org.vitrivr.engine.core.database.descriptor.DescriptorReader
+import org.vitrivr.engine.core.model.metamodel.Schema
+import org.vitrivr.engine.core.model.retrievable.Relationship
+import org.vitrivr.engine.core.model.retrievable.Retrieved
+import org.vitrivr.engine.core.model.retrievable.attributes.DescriptorAttribute
+import org.vitrivr.engine.core.model.retrievable.attributes.RelationshipAttribute
+import org.vitrivr.engine.core.operators.Operator
+import org.vitrivr.engine.core.operators.retrieve.Transformer
+
+/**
+ * Appends [DescriptorAttribute] to a [Retrieved] in a specified object [Relationship] based on lookup values of a [Schema.Field], if available.
+ *
+ * @version 1.0.0
+ * @author Luca Rossetto
+ * @author Ralph Gasser
+ */
+class ObjectFieldLookup(override val input: Operator<Retrieved>, private val reader: DescriptorReader<*>, private val predicates: Set<String>) : Transformer {
+    override fun toFlow(scope: CoroutineScope): Flow<Retrieved> = flow {
+        /* Parse input IDs.*/
+        val inputRetrieved = input.toFlow(scope).toList()
+
+        /* Fetch Retrievable entries that should be enriched. */
+        val enrich = inputRetrieved.mapNotNull { it.filteredAttribute(RelationshipAttribute::class.java) }.flatMap { r ->
+            r.relationships.filter { this@ObjectFieldLookup.predicates.isEmpty() || it.pred in this@ObjectFieldLookup.predicates }.mapNotNull { it.obj.second }
+        }
+        val ids = enrich.map { it.id }
+        val descriptors = if (ids.isNotEmpty()) {
+            this@ObjectFieldLookup.reader.getAllBy(ids, "retrievableId").filter { it.retrievableId != null }.associateBy { it.retrievableId!! }
+        } else {
+            emptyMap()
+        }
+
+        /* Emit retrievable with added attribute. */
+        enrich.forEach {
+            val descriptor = descriptors[it.id]
+            if (descriptor != null) {
+                it.addAttribute(DescriptorAttribute(descriptor))
+            }
+        }
+
+        /* Emit input. */
+        inputRetrieved.forEach { emit(it) }
+    }
+}

vitrivr-engine-query/src/main/kotlin/org/vitrivr/engine/query/transform/lookup/ObjectFieldLookupFactory.kt

@@ -0,0 +1,22 @@
+package org.vitrivr.engine.query.transform.lookup
+
+import org.vitrivr.engine.core.model.metamodel.Schema
+import org.vitrivr.engine.core.model.retrievable.Retrieved
+import org.vitrivr.engine.core.operators.Operator
+import org.vitrivr.engine.core.operators.retrieve.TransformerFactory
+
+
+/**
+ * [TransformerFactory] for [ObjectFieldLookup].
+ *
+ * @version 1.0.0
+ * @author Ralph Gasser
+ */
+class ObjectFieldLookupFactory() : TransformerFactory {
+    override fun newTransformer(input: Operator<Retrieved>, schema: Schema, properties: Map<String, String>): ObjectFieldLookup {
+        val field = properties["field"] ?: throw IllegalArgumentException("Expected 'field' to be defined in properties")
+        val predicates = properties["predicates"]?.split(",")?.toSet() ?: emptySet()
+        val reader = (schema[field] ?: throw IllegalArgumentException("Field '$field' not defined in schema")).getReader()
+        return ObjectFieldLookup(input, reader, predicates)
+    }
+}

vitrivr-engine-query/src/main/resources/META-INF/services/org.vitrivr.engine.core.operators.retrieve.TransformerFactory

@@ -1,3 +1,4 @@
 org.vitrivr.engine.query.transform.RelationExpanderFactory
 org.vitrivr.engine.query.transform.ScoreAggregatorFactory
-org.vitrivr.engine.query.transform.FieldLookupFactory
+org.vitrivr.engine.query.transform.lookup.FieldLookupFactory
+org.vitrivr.engine.query.transform.lookup.ObjectFieldLookupFactory