add support for cascading deletes on dependent entities

wizard-common/src/main/java/org/cobbzilla/wizard/model/entityconfig/EntityFieldReference.java

@@ -1,6 +1,8 @@
 package org.cobbzilla.wizard.model.entityconfig;
 
+import lombok.EqualsAndHashCode;
 import lombok.Getter;
+import lombok.NoArgsConstructor;
 import lombok.Setter;
 
 import static org.cobbzilla.util.daemon.ZillaRuntime.empty;
@@ -9,8 +11,14 @@ import static org.cobbzilla.util.daemon.ZillaRuntime.empty;
  * When the EntityFieldType of a field is 'reference', this object is also attached to the field to describe
  * how to reach the reference.
  */
+@NoArgsConstructor @EqualsAndHashCode(of={"entity", "field"})
 public class EntityFieldReference {
 
+    public EntityFieldReference (String entity, String field) {
+        this.entity = entity;
+        this.field = field;
+    }
+
     /** A special value that can be used by child entities to indicate that the lexically enclosing entity is their parent. */
     public static final String REF_PARENT = ":parent";
 

wizard-common/src/main/java/org/cobbzilla/wizard/model/entityconfig/EntityReferences.java

@@ -14,9 +14,7 @@ import org.cobbzilla.wizard.model.entityconfig.annotations.ECIndexes;
 import org.cobbzilla.wizard.util.ClasspathScanner;
 
 import java.lang.reflect.Field;
-import java.util.ArrayList;
-import java.util.Arrays;
-import java.util.List;
+import java.util.*;
 import java.util.function.Function;
 import java.util.function.Predicate;
 import java.util.stream.Collectors;
@@ -56,6 +54,42 @@ public class EntityReferences {
         return topology.sortReversed();
     }
 
+    public static boolean hasForeignKey(Class candidate, Class<? extends Identifiable> entityClass) {
+        if (candidate.equals(Object.class)) return false;
+        if (Arrays.stream(candidate.getDeclaredFields())
+                .filter(EntityReferences.FIELD_HAS_FK)
+                .anyMatch(f -> f.getAnnotation(ECForeignKey.class).entity().equals(entityClass))) {
+            return true;
+        }
+        return hasForeignKey(candidate.getSuperclass(), entityClass);
+    }
+
+    public static List<Class<? extends Identifiable>> getDependentEntities(Class<? extends Identifiable> entityClass, List<Class<? extends Identifiable>> candidates) {
+        return candidates.stream()
+                .filter(candidate -> hasForeignKey(candidate, entityClass))
+                .collect(Collectors.toList());
+    }
+
+    public static Collection<EntityFieldReference> getDependencyRefs(Class<? extends Identifiable> entityClass,
+                                                                     List<Class<? extends Identifiable>> candidates) {
+        final Set<EntityFieldReference> refs = new LinkedHashSet<>();
+        candidates.forEach(dep -> refs.addAll(getDependencyRefs(entityClass, dep, dep, refs)));
+        return refs;
+    }
+
+    private static Set<EntityFieldReference> getDependencyRefs(Class<? extends Identifiable> entityClass,
+                                                               Class dependency,
+                                                               Class dependencyOrParent,
+                                                               Set<EntityFieldReference> refs) {
+        if (dependencyOrParent.equals(Object.class)) return refs;
+        Arrays.stream(dependencyOrParent.getDeclaredFields())
+                .filter(FIELD_HAS_FK)
+                .filter(f -> f.getAnnotation(ECForeignKey.class).entity().equals(entityClass))
+                .forEach(f -> refs.add(new EntityFieldReference(dependency.getSimpleName(), f.getName())));
+        refs.addAll(getDependencyRefs(entityClass, dependency, dependencyOrParent.getSuperclass(), refs));
+        return refs;
+    }
+
     public List<String> generateConstraintSql() { return generateConstraintSql(true); }
 
     public List<String> generateConstraintSql(boolean includeIndexes) {

wizard-server/src/main/java/org/cobbzilla/wizard/server/config/PgRestServerConfiguration.java

@@ -16,6 +16,7 @@ import org.cobbzilla.util.string.StringUtil;
 import org.cobbzilla.util.system.Command;
 import org.cobbzilla.util.system.CommandResult;
 import org.cobbzilla.wizard.model.Identifiable;
+import org.cobbzilla.wizard.model.entityconfig.EntityFieldReference;
 import org.cobbzilla.wizard.model.entityconfig.EntityReferences;
 import org.springframework.context.annotation.Bean;
 
@@ -23,6 +24,7 @@ import javax.persistence.Transient;
 import java.io.File;
 import java.sql.*;
 import java.util.*;
+import java.util.concurrent.ConcurrentHashMap;
 import java.util.regex.Pattern;
 import java.util.stream.Collectors;
 
@@ -37,6 +39,8 @@ import static org.cobbzilla.util.string.StringUtil.camelCaseToSnakeCase;
 import static org.cobbzilla.util.string.StringUtil.checkSafeShellArg;
 import static org.cobbzilla.util.system.CommandShell.exec;
 import static org.cobbzilla.util.system.CommandShell.execScript;
+import static org.cobbzilla.wizard.model.entityconfig.EntityReferences.getDependencyRefs;
+import static org.cobbzilla.wizard.model.entityconfig.EntityReferences.getDependentEntities;
 
 @Slf4j
 public class PgRestServerConfiguration extends RestServerConfiguration implements HasDatabaseConfiguration {
@@ -324,6 +328,23 @@ public class PgRestServerConfiguration extends RestServerConfiguration implement
         return reversed;
     }
 
+    private Map<Class<? extends Identifiable>, List<Class<? extends Identifiable>>> dependencyCache = new ConcurrentHashMap<>();
+    public List<Class<? extends Identifiable>> getDependencies (Class<? extends Identifiable> entityClass) {
+        return dependencyCache.computeIfAbsent(entityClass, c -> getDependentEntities(entityClass, getEntityClassesReverse()));
+    }
+
+    private Map<Class<? extends Identifiable>, Collection<EntityFieldReference>> dependencyDAOCache = new ConcurrentHashMap<>();
+    public Collection<EntityFieldReference> dependencyRefs(Class<? extends Identifiable> entityClass) {
+        return dependencyDAOCache.computeIfAbsent(entityClass, c -> getDependencyRefs(c, getDependencies(c)));
+    }
+
+    public void deleteDependencies (Identifiable thing) {
+        final String[] uuidArg = {thing.getUuid()};
+        dependencyRefs(thing.getClass()).forEach(
+                dep -> execSql("DELETE FROM " + camelCaseToSnakeCase(dep.getEntity()) + " WHERE " + camelCaseToSnakeCase(dep.getField()) + " = ?", uuidArg)
+        );
+    }
+
     @Getter(lazy=true) private final List<NameAndValue> sortedSimpleEntityClassMap = initSortedSimpleEntityClassMap();
     private List<NameAndValue> initSortedSimpleEntityClassMap() {
         return getEntityClasses().stream()