#417 - ENH: Add JSON expressions ... path exists and value at path equals value

src/main/java/com/avaje/ebeaninternal/server/expression/JsonPathExpression.java

@@ -0,0 +1,69 @@
+package com.avaje.ebeaninternal.server.expression;
+
+import com.avaje.ebean.event.BeanQueryRequest;
+import com.avaje.ebeaninternal.api.HashQueryPlanBuilder;
+import com.avaje.ebeaninternal.api.SpiExpressionRequest;
+
+/**
+ * Generally speaking tests the value at a given path in the JSON document.
+ * <p>
+ * Supports the usual operators (equal to, greater than etc).
+ * </p>
+ * <p>
+ * The value passed in is expected to be a valid JSON type so string, number, boolean.
+ * </p>
+ */
+class JsonPathExpression extends AbstractExpression {
+
+  /**
+   * The path in the JSON document in dot notation form.
+   */
+  protected final String path;
+
+  /**
+   * The expression operator.
+   */
+  protected final Op operator;
+
+  /**
+   * The bind value used to compare against the document path value.
+   */
+  protected final Object value;
+
+  JsonPathExpression(String propertyName, String path, Op operator, Object value) {
+    super(propertyName);
+    this.path = path;
+    this.operator = operator;
+    this.value = value;
+  }
+
+  @Override
+  public void queryAutoTuneHash(HashQueryPlanBuilder builder) {
+    builder.add(JsonPathExpression.class).add(propName).add(path).add(operator);
+  }
+
+  @Override
+  public void queryPlanHash(BeanQueryRequest<?> request, HashQueryPlanBuilder builder) {
+    queryAutoTuneHash(builder);
+  }
+
+  @Override
+  public int queryBindHash() {
+    return (value == null) ? 0 : value.hashCode();
+  }
+
+  @Override
+  public void addSql(SpiExpressionRequest request) {
+
+    // Use DB specific expression handling (Postgres and Oracle supported)
+    request.getJsonHander().addSql(request, propName, path, operator, value);
+  }
+
+  @Override
+  public void addBindValues(SpiExpressionRequest request) {
+
+    if (value != null) {
+      request.addBindValue(value);
+    }
+  }
+}