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

…uals value

src/main/java/com/avaje/ebean/ExpressionFactory.java

@@ -36,6 +36,46 @@
  */
 public interface ExpressionFactory {
 
+  /**
+   * Path exists - for the given path in a JSON document.
+   */
+  Expression jsonExists(String propertyName, String path);
+
+  /**
+   * Path does not exist - for the given path in a JSON document.
+   */
+  Expression jsonNotExists(String propertyName, String path);
+
+  /**
+   * Equal to - for the given path in a JSON document.
+   */
+  Expression jsonEqualTo(String propertyName, String path, Object val);
+
+  /**
+   * Not Equal to - for the given path in a JSON document.
+   */
+  Expression jsonNotEqualTo(String propertyName, String path, Object val);
+
+  /**
+   * Greater than - for the given path in a JSON document.
+   */
+  Expression jsonGreaterThan(String propertyName, String path, Object val);
+
+  /**
+   * Greater than or equal to - for the given path in a JSON document.
+   */
+  Expression jsonGreaterOrEqual(String propertyName, String path, Object val);
+
+  /**
+   * Less than - for the given path in a JSON document.
+   */
+  Expression jsonLessThan(String propertyName, String path, Object val);
+
+  /**
+   * Less than or equal to - for the given path in a JSON document.
+   */
+  Expression jsonLessOrEqualTo(String propertyName, String path, Object val);
+
   /**
    * Equal To - property equal to the given value.
    */

src/main/java/com/avaje/ebean/ExpressionList.java

@@ -345,12 +345,66 @@ public interface ExpressionList<T> extends Serializable {
    */
   ExpressionList<T> where();
 
+  /**
+   * Path exists - for the given path in a JSON document.
+   *
+   * @param propertyName the property that holds a JSON document
+   * @param path the nested path in the JSON document in dot notation
+   */
+  ExpressionList<T> jsonExists(String propertyName, String path);
+
+  /**
+   * Path does not exist - for the given path in a JSON document.
+   *
+   * @param propertyName the property that holds a JSON document
+   * @param path the nested path in the JSON document in dot notation
+   */
+  ExpressionList<T> jsonNotExists(String propertyName, String path);
+
+  /**
+   * Equal to expression for the value at the given path in the JSON document.
+   *
+   * @param propertyName the property that holds a JSON document
+   * @param path the nested path in the JSON document in dot notation
+   * @param value the value used to test equality against the document path's value
+   */
+  ExpressionList<T> jsonEqualTo(String propertyName, String path, Object value);
+
+  /**
+   * Not Equal to - for the given path in a JSON document.
+   *
+   * @param propertyName the property that holds a JSON document
+   * @param path the nested path in the JSON document in dot notation
+   * @param value the value used to test equality against the document path's value
+   */
+  ExpressionList<T> jsonNotEqualTo(String propertyName, String path, Object value);
+
+  /**
+   * Greater than - for the given path in a JSON document.
+   */
+  ExpressionList<T> jsonGreaterThan(String propertyName, String path, Object val);
+
+  /**
+   * Greater than or equal to - for the given path in a JSON document.
+   */
+  ExpressionList<T> jsonGreaterOrEqual(String propertyName, String path, Object val);
+
+  /**
+   * Less than - for the given path in a JSON document.
+   */
+  ExpressionList<T> jsonLessThan(String propertyName, String path, Object val);
+
+  /**
+   * Less than or equal to - for the given path in a JSON document.
+   */
+  ExpressionList<T> jsonLessOrEqualTo(String propertyName, String path, Object val);
+
   /**
    * Add an Expression to the list.
    * <p>
    * This returns the list so that add() can be chained.
    * </p>
-   * 
+   *
    * <pre>{@code
    *
    * Query<Customer> query = Ebean.find(Customer.class);

src/main/java/com/avaje/ebeaninternal/api/SpiExpressionRequest.java

@@ -2,6 +2,7 @@
 
 import java.util.ArrayList;
 
+import com.avaje.ebeaninternal.server.core.JsonExpressionHandler;
 import com.avaje.ebeaninternal.server.core.SpiOrmQueryRequest;
 import com.avaje.ebeaninternal.server.deploy.BeanDescriptor;
 
@@ -10,6 +11,11 @@
  */
 public interface SpiExpressionRequest {
 
+  /**
+   * Return the DB specific JSON expression handler.
+   */
+  JsonExpressionHandler getJsonHander();
+
   /**
    * Parse the logical property name to the deployment name.
    */

src/main/java/com/avaje/ebeaninternal/server/core/InternalConfiguration.java

@@ -209,11 +209,29 @@ public ReadAuditPrepare getReadAuditPrepare() {
    * For 'As Of' queries return the number of bind variables per predicate.
    */
   private Binder getBinder(TypeManager typeManager, DatabasePlatform databasePlatform) {
+
+    JsonExpressionHandler jsonHandler = getJsonExpressionHandler(databasePlatform);
+
     DbHistorySupport historySupport = databasePlatform.getHistorySupport();
     if (historySupport == null) {
-      return new Binder(typeManager, 0, false);
+      return new Binder(typeManager, 0, false, jsonHandler);
+    }
+    return new Binder(typeManager, historySupport.getBindCount(), historySupport.isBindWithFromClause(), jsonHandler);
+  }
+
+  /**
+   * Return the JSON expression handler for the given database platform.
+   */
+  private JsonExpressionHandler getJsonExpressionHandler(DatabasePlatform databasePlatform) {
+
+    String name = databasePlatform.getName();
+    if ("postgres".equalsIgnoreCase(name)) {
+      return new PostgresJsonExpression();
+    }
+    if ("oracle".equalsIgnoreCase(name)) {
+      return new OracleJsonExpression();
     }
-    return new Binder(typeManager, historySupport.getBindCount(), historySupport.isBindWithFromClause());
+    return new NotSupportedJsonExpression();
   }
 
   /**

src/main/java/com/avaje/ebeaninternal/server/core/JsonExpressionHandler.java

@@ -0,0 +1,17 @@
+package com.avaje.ebeaninternal.server.core;
+
+import com.avaje.ebeaninternal.api.SpiExpressionRequest;
+import com.avaje.ebeaninternal.server.expression.Op;
+
+/**
+ * Adds the db platform specific json expression.
+ */
+public interface JsonExpressionHandler {
+
+
+  /**
+   * Write the db platform specific json expression.
+   */
+  void addSql(SpiExpressionRequest request, String propName, String path, Op operator, Object value);
+
+}

src/main/java/com/avaje/ebeaninternal/server/core/NotSupportedJsonExpression.java

@@ -0,0 +1,15 @@
+package com.avaje.ebeaninternal.server.core;
+
+import com.avaje.ebeaninternal.api.SpiExpressionRequest;
+import com.avaje.ebeaninternal.server.expression.Op;
+
+/**
+ * Not supported JSON expression handler.
+ */
+public class NotSupportedJsonExpression implements JsonExpressionHandler {
+
+  @Override
+  public void addSql(SpiExpressionRequest request, String propName, String path, Op operator, Object value) {
+    throw new RuntimeException("JSON expressions only supported on Postgres and Oracle");
+  }
+}

src/main/java/com/avaje/ebeaninternal/server/core/OracleJsonExpression.java

@@ -0,0 +1,24 @@
+package com.avaje.ebeaninternal.server.core;
+
+import com.avaje.ebeaninternal.api.SpiExpressionRequest;
+import com.avaje.ebeaninternal.server.expression.Op;
+
+/**
+ * Postgres JSON expression handler
+ */
+public class OracleJsonExpression implements JsonExpressionHandler {
+
+  @Override
+  public void addSql(SpiExpressionRequest request, String propName, String path, Op operator, Object value) {
+
+    if (operator == Op.EXISTS) {
+      request.append("json_exists(").append(propName).append(", '$.").append(path).append("')");
+    } else if (operator == Op.NOT_EXISTS) {
+      request.append("not json_exists(").append(propName).append(", '$.").append(path).append("')");
+    } else {
+      request.append("json_value(").append(propName).append(", '$.").append(path).append("')");
+      request.append(operator.bind());
+    }
+
+  }
+}

src/main/java/com/avaje/ebeaninternal/server/core/PostgresJsonExpression.java

@@ -0,0 +1,71 @@
+package com.avaje.ebeaninternal.server.core;
+
+import com.avaje.ebeaninternal.api.SpiExpressionRequest;
+import com.avaje.ebeaninternal.server.expression.Op;
+
+/**
+ * Postgres JSON expression handler
+ */
+public class PostgresJsonExpression implements JsonExpressionHandler {
+
+  @Override
+  public void addSql(SpiExpressionRequest request, String propName, String path, Op operator, Object value) {
+
+    StringBuilder sb = new StringBuilder(50);
+    String[] paths = path.split("\\.");
+    if (paths.length == 1) {
+      // (t0.content ->> 'title') = 'Some value'
+      sb.append("(").append(propName).append(" ->> '").append(path).append("')");
+
+    } else {
+      // (t0.content #>> '{path,inner}') = 'Some value'
+      sb.append("(").append(propName).append(" #>> '{");
+      for (int i = 0; i < paths.length; i++) {
+        if (i > 0) {
+          sb.append(",");
+        }
+        sb.append(paths[i]);
+      }
+      sb.append("}')");
+    }
+
+    request.append(castType(sb.toString(), value));
+    request.append(operator.bind());
+  }
+
+  /**
+   * Postgres CAST the type if necessary as text values always returned from the json operators used.
+   */
+  private String castType(String expression, Object value) {
+
+    if (value == null) {
+      // for exists and not-exists expressions
+      return expression;
+    }
+
+    // Postgres cast of returned text value
+    if (isIntegerType(value)) {
+      return expression+"::INTEGER";
+    }
+    if (isNumberType(value)) {
+      return expression+"::DECIMAL";
+    }
+    if (isBooleanType(value)) {
+      return expression+"::BOOLEAN";
+    }
+
+    return expression;
+  }
+
+  private boolean isBooleanType(Object value) {
+    return (value instanceof Boolean);
+  }
+
+  private boolean isIntegerType(Object value) {
+    return (value instanceof Integer) || (value instanceof Long);
+  }
+
+  private boolean isNumberType(Object value) {
+    return (value instanceof Number);
+  }
+}

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

@@ -211,7 +211,7 @@ private ArrayList<SpiExpression> buildExpressions(BeanQueryRequest<?> request) {
           // exclude the zero values typically to weed out
           // primitive int and long that initialise to 0
           if (includeZeros || !isZero(value)) {
-            list.add(new SimpleExpression(propName, SimpleExpression.Op.EQ, value));
+            list.add(new SimpleExpression(propName, Op.EQ, value));
           }
         }
       }