From 2332c6d0b35c9b18a13e8c0bce4a3a18e78c590d Mon Sep 17 00:00:00 2001
From: Robert von Burg <eitch@eitchnet.ch>
Date: Fri, 20 Mar 2020 14:57:31 +0100
Subject: [PATCH] [New] Added tx.getPolicyDef(PolicyDef, PolicyDef)

---
 .../persistence/api/AbstractTransaction.java      |  5 +++++
 .../persistence/api/StrolchTransaction.java       | 14 ++++++++++++++
 .../li/strolch/policy/DefaultPolicyHandler.java   | 12 +++++++++++-
 .../java/li/strolch/policy/PolicyHandler.java     | 15 +++++++++++++++
 4 files changed, 45 insertions(+), 1 deletion(-)

diff --git a/li.strolch.agent/src/main/java/li/strolch/persistence/api/AbstractTransaction.java b/li.strolch.agent/src/main/java/li/strolch/persistence/api/AbstractTransaction.java
index a6427ed99..1e07f5e80 100644
--- a/li.strolch.agent/src/main/java/li/strolch/persistence/api/AbstractTransaction.java
+++ b/li.strolch.agent/src/main/java/li/strolch/persistence/api/AbstractTransaction.java
@@ -385,6 +385,11 @@ public abstract class AbstractTransaction implements StrolchTransaction {
 		return getContainer().getComponent(PolicyHandler.class).getPolicy(policyDef, this);
 	}
 
+	@Override
+	public <T extends StrolchPolicy> T getPolicy(PolicyDef policyDef, PolicyDef defaultDef) {
+		return getContainer().getComponent(PolicyHandler.class).getPolicy(policyDef, defaultDef, this);
+	}
+
 	private void assertQueryAllowed(StrolchQuery query) {
 		try {
 			getPrivilegeContext().validateAction(query);
diff --git a/li.strolch.agent/src/main/java/li/strolch/persistence/api/StrolchTransaction.java b/li.strolch.agent/src/main/java/li/strolch/persistence/api/StrolchTransaction.java
index a58b82fbb..c67000426 100644
--- a/li.strolch.agent/src/main/java/li/strolch/persistence/api/StrolchTransaction.java
+++ b/li.strolch.agent/src/main/java/li/strolch/persistence/api/StrolchTransaction.java
@@ -184,6 +184,20 @@ public interface StrolchTransaction extends AutoCloseable {
 	 */
 	<T extends StrolchPolicy> T getPolicy(PolicyDef policyDef);
 
+	/**
+	 * Instantiates the policy using the given {@link PolicyDef}, or if not available, the default policy
+	 *
+	 * @param policyDef
+	 * 		the policy definition
+	 * @param defaultDef
+	 * 		the default policy definition if the given policy definition is unavailable
+	 * @param <T>
+	 * 		the type of policy to return
+	 *
+	 * @return the policy
+	 */
+	<T extends StrolchPolicy> T getPolicy(PolicyDef policyDef, PolicyDef defaultDef);
+
 	/**
 	 * Returns the currently set {@link TransactionCloseStrategy}
 	 *
diff --git a/li.strolch.agent/src/main/java/li/strolch/policy/DefaultPolicyHandler.java b/li.strolch.agent/src/main/java/li/strolch/policy/DefaultPolicyHandler.java
index 6e8c6d9a8..4cc4fed64 100644
--- a/li.strolch.agent/src/main/java/li/strolch/policy/DefaultPolicyHandler.java
+++ b/li.strolch.agent/src/main/java/li/strolch/policy/DefaultPolicyHandler.java
@@ -94,11 +94,21 @@ public class DefaultPolicyHandler extends StrolchComponent implements PolicyHand
 
 	@Override
 	public <T extends StrolchPolicy> T getPolicy(PolicyDef policyDef, StrolchTransaction tx) {
+		return getPolicy(policyDef, null, tx);
+	}
+
+	@Override
+	public <T extends StrolchPolicy> T getPolicy(PolicyDef policyDef, PolicyDef defaultDef, StrolchTransaction tx) {
 		DBC.PRE.assertNotNull("policyDef must not be null!", policyDef);
 		DBC.PRE.assertNotNull("tx must not be null!", tx);
 		try {
 
-			Class<T> clazz = policyDef.accept(this);
+			Class<T> clazz;
+			if (defaultDef != null && !isPolicyDefAvailable(policyDef))
+				clazz = defaultDef.accept(this);
+			else
+				clazz = policyDef.accept(this);
+
 			@SuppressWarnings("unchecked")
 			Constructor<T> constructor = (Constructor<T>) getConstructorForPolicy(clazz);
 			if (constructor.getParameterCount() == 1)
diff --git a/li.strolch.agent/src/main/java/li/strolch/policy/PolicyHandler.java b/li.strolch.agent/src/main/java/li/strolch/policy/PolicyHandler.java
index 59b6b3602..cf7bc17af 100644
--- a/li.strolch.agent/src/main/java/li/strolch/policy/PolicyHandler.java
+++ b/li.strolch.agent/src/main/java/li/strolch/policy/PolicyHandler.java
@@ -73,6 +73,21 @@ public interface PolicyHandler {
 	 */
 	<T extends StrolchPolicy> T getPolicy(PolicyDef policyDef, StrolchTransaction tx);
 
+	/**
+	 * Instantiates the actual policy by resolving the {@link PolicyDef} using a {@link PolicyDefVisitor}, or if not
+	 * available, using the default policy definition
+	 *
+	 * @param policyDef
+	 * 		the {@link PolicyDef} referencing a concrete policy
+	 * @param defaultDef
+	 * 		the default {@link PolicyDef} to use if the other is not available
+	 * @param tx
+	 * 		the current transaction for which the policy is instantiated
+	 *
+	 * @return the instantiated instance of the referenced policy
+	 */
+	<T extends StrolchPolicy> T getPolicy(PolicyDef policyDef, PolicyDef defaultDef, StrolchTransaction tx);
+
 	/**
 	 * Returns true, if the policy definition is known
 	 *