#1145 - Refactor @ChangeLog based on JSON documents for 'new values' and 'old values'

src/main/java/io/ebeaninternal/server/deploy/BeanChangeJson.java

@@ -0,0 +1,108 @@
+package io.ebeaninternal.server.deploy;
+
+import io.ebean.PersistenceIOException;
+import io.ebean.bean.BeanDiffVisitor;
+import io.ebeaninternal.server.text.json.SpiJsonWriter;
+import io.ebeaninternal.server.util.ArrayStack;
+
+import java.io.IOException;
+import java.io.StringWriter;
+
+/**
+ * Builds the 'new values' and 'old values' in JSON form for ChangeLog.
+ */
+class BeanChangeJson implements BeanDiffVisitor {
+
+  private final StringWriter newData;
+  private final StringWriter oldData;
+
+  private final SpiJsonWriter newJson;
+  private final SpiJsonWriter oldJson;
+
+  private final ArrayStack<BeanDescriptor<?>> stack = new ArrayStack<>();
+
+  private BeanDescriptor<?> descriptor;
+
+  BeanChangeJson(BeanDescriptor<?> descriptor, boolean statelessUpdate) {
+    this.descriptor = descriptor;
+    this.newData = new StringWriter(200);
+    this.newJson = descriptor.createJsonWriter(newData);
+    newJson.writeStartObject();
+
+    if (statelessUpdate) {
+      this.oldJson = null;
+      this.oldData = null;
+    } else {
+      this.oldData = new StringWriter(200);
+      this.oldJson = descriptor.createJsonWriter(oldData);
+      oldJson.writeStartObject();
+    }
+  }
+
+  @Override
+  public void visit(int position, Object newVal, Object oldVal) {
+
+    try {
+      BeanProperty prop = descriptor.propertiesIndex[position];
+      if (prop.isDbUpdatable()) {
+        prop.jsonWriteValue(newJson, newVal);
+        if (oldJson != null) {
+          prop.jsonWriteValue(oldJson, oldVal);
+        }
+      }
+    } catch (IOException e) {
+      throw new PersistenceIOException(e);
+    }
+  }
+
+  @Override
+  public void visitPush(int position) {
+    stack.push(descriptor);
+
+    BeanPropertyAssocOne<?> embedded = (BeanPropertyAssocOne<?>)descriptor.propertiesIndex[position];
+    descriptor = embedded.getTargetDescriptor();
+    newJson.writeStartObject(embedded.getName());
+    if (oldJson != null) {
+      oldJson.writeStartObject(embedded.getName());
+    }
+  }
+
+  @Override
+  public void visitPop() {
+    newJson.writeEndObject();
+    if (oldJson != null) {
+      oldJson.writeEndObject();
+    }
+    descriptor = stack.pop();
+  }
+
+  /**
+   * Flush the buffers.
+   */
+  void flush() {
+    try {
+      newJson.writeEndObject();
+      newJson.gen().flush();
+      if (oldJson != null) {
+        oldJson.writeEndObject();
+        oldJson.gen().flush();
+      }
+    } catch (IOException e) {
+      throw new PersistenceIOException(e);
+    }
+  }
+
+  /**
+   * Return the new values JSON.
+   */
+  String newJson() {
+    return newData.toString();
+  }
+
+  /**
+   * Return the old values JSON.
+   */
+  String oldJson() {
+    return oldData == null ? null : oldData.toString();
+  }
+}