Add variable support for call mediator and improve synapse expression

modules/core/src/main/java/org/apache/synapse/config/xml/CallMediatorFactory.java

@@ -237,8 +237,15 @@ private void populateTarget(CallMediator callMediator, Target target, OMElement
             }
         } else if (target.getTargetType() == EnrichMediator.BODY) {
             callMediator.setTargetAvailable(false);
+        } else if (target.getTargetType() == EnrichMediator.VARIABLE) {
+            // check if variable is surrounded by curly braces
+            if (StringUtils.isNotEmpty(sourceEle.getText())) {
+                callMediator.setTargetAvailable(true);
+                target.setVariable(new ValueFactory().createTextValue(sourceEle));
+            } else {
+                handleException("Variable name is required for VARIABLE type");
+            }
         }
-
     }
 
     public QName getTagQName() {

modules/core/src/main/java/org/apache/synapse/config/xml/CallMediatorSerializer.java

@@ -108,6 +108,8 @@ private OMElement serializeTarget(Target target) {
         targetEle.addAttribute(fac.createOMAttribute("type", nullNS, intTypeToString(target.getTargetType())));
         if (target.getTargetType() == EnrichMediator.PROPERTY) {
             targetEle.setText(target.getProperty());
+        } else if (target.getTargetType() == EnrichMediator.VARIABLE) {
+            targetEle.setText(target.getVariable().getKeyValue());
         }
 
         return targetEle;

modules/core/src/main/java/org/apache/synapse/config/xml/ValueFactory.java

@@ -111,6 +111,10 @@ public Value createTextValue(OMElement elem) {
                     textValue = textValue.substring(1, textValue.length() - 1);
                     SynapseJsonPath synJsonPath = createSynJsonPath(textValue);
                     key = new Value(synJsonPath);
+                } else if (textValue.startsWith("{${") && textValue.endsWith("}}")) {
+                    textValue = textValue.substring(1, textValue.length() - 1);
+                    SynapseExpression synapseExpression = createSynapseExpression(textValue);
+                    key = new Value(synapseExpression);
                 } else {
                     SynapseXPath synXpath = createSynXpath(elem, textValue);
                     key = new Value(synXpath);

modules/core/src/main/java/org/apache/synapse/mediators/builtin/CallMediator.java

@@ -44,6 +44,7 @@
 import org.apache.synapse.endpoints.EndpointDefinition;
 import org.apache.synapse.endpoints.IndirectEndpoint;
 import org.apache.synapse.mediators.AbstractMediator;
+import org.apache.synapse.mediators.elementary.EnrichMediator;
 import org.apache.synapse.mediators.elementary.Source;
 import org.apache.synapse.mediators.elementary.Target;
 import org.apache.synapse.message.senders.blocking.BlockingMsgSender;
@@ -167,8 +168,11 @@ public boolean mediate(MessageContext synInCtx) {
             sourceForInboundPayload.setClone(true);
             CallMediatorEnrichUtil
                     .doEnrich(synInCtx, sourceForInboundPayload, targetForOriginalPayload, originalMessageType);
-            CallMediatorEnrichUtil
-                    .doEnrich(synInCtx, sourceForOutboundPayload, targetForOutboundPayload, getSourceMessageType());
+            if (!(EnrichMediator.BODY == sourceForOutboundPayload.getSourceType() &&
+                EnrichMediator.BODY == targetForOutboundPayload.getTargetType())) {
+                CallMediatorEnrichUtil
+                        .doEnrich(synInCtx, sourceForOutboundPayload, targetForOutboundPayload, getSourceMessageType());
+            }
             if (!sourceMessageType.equalsIgnoreCase(originalMessageType)) {
                 CallMediatorEnrichUtil.setContentType(synInCtx, sourceMessageType, sourceMessageType);
                 if (originalMessageType.equalsIgnoreCase(JSON_TYPE)) {

modules/core/src/main/java/org/apache/synapse/mediators/eip/EIPUtils.java

@@ -434,4 +434,8 @@ public Set<Option> options() {
         });
     }
 
+    public static JsonObject convertMapToJsonObj(Object map) {
+        return new GsonBuilder().create().toJsonTree(map).getAsJsonObject();
+    }
+
 }

modules/core/src/main/java/org/apache/synapse/mediators/elementary/EnrichMediator.java

@@ -85,6 +85,8 @@ public class EnrichMediator extends AbstractMediator {
 
     public static final int KEY = 5;
 
+    public static final int VARIABLE = 6;
+
     private Source source = null;
 
     private Target target = null;

modules/core/src/main/java/org/apache/synapse/mediators/elementary/Target.java

@@ -42,23 +42,29 @@
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import org.apache.synapse.MessageContext;
+import org.apache.synapse.SynapseConstants;
 import org.apache.synapse.SynapseException;
 import org.apache.synapse.SynapseLog;
 import org.apache.synapse.commons.json.Constants;
 import org.apache.synapse.commons.json.JsonUtil;
 import org.apache.synapse.config.xml.SynapsePath;
 import org.apache.synapse.config.xml.XMLConfigConstants;
 import org.apache.synapse.core.axis2.Axis2MessageContext;
+import org.apache.synapse.mediators.Value;
 import org.apache.synapse.mediators.eip.EIPUtils;
+import org.apache.synapse.util.CallMediatorEnrichUtil;
 import org.apache.synapse.util.InlineExpressionUtil;
+import org.apache.synapse.util.synapse.expression.constants.ExpressionConstants;
 import org.apache.synapse.util.xpath.SynapseJsonPath;
 import org.apache.synapse.util.xpath.SynapseXPath;
 import org.apache.synapse.util.xpath.SynapseXPathConstants;
 import org.jaxen.JaxenException;
 
 import java.io.IOException;
 import java.util.ArrayList;
+import java.util.HashMap;
 import java.util.List;
+import java.util.Map;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
@@ -87,6 +93,8 @@ public class Target {
 
     private String property = null;
 
+    private Value variable = null;
+
     private int targetType = EnrichMediator.CUSTOM;
 
     public static final String ACTION_REMOVE = "remove";
@@ -232,6 +240,27 @@ public void insert(MessageContext synContext,
 			}else{
 			synContext.setProperty(property, sourceNodeList);  
 			}
+        } else if (targetType == EnrichMediator.VARIABLE) {
+            if (action.equalsIgnoreCase(ACTION_REPLACE)) {
+                String key = variable.evaluateValue(synContext);
+                if (StringUtils.isEmpty(key)) {
+                    synLog.error("Variable key cannot be null");
+                    throw new SynapseException("Variable key cannot be null");
+                }
+                Map<String, Object> result = new HashMap<>();
+                result.put(ExpressionConstants.PAYLOAD, sourceNodeList);
+                Map transportHeaders = (Map)((Axis2MessageContext) synContext).getAxis2MessageContext()
+                        .getProperty(org.apache.axis2.context.MessageContext.TRANSPORT_HEADERS);
+                JsonObject headers = EIPUtils.convertMapToJsonObj(transportHeaders);
+                result.put(ExpressionConstants.HEADERS, headers);
+                result.put(ExpressionConstants.ATTRIBUTES, CallMediatorEnrichUtil.populateTransportAttributes(synContext));
+                synContext.setVariable(key, result);
+            } else {
+                synLog.error("Action " + action + " is not supported when enriching variables");
+            }
+        } else {
+            synLog.error("Invalid Target type");
+            throw new SynapseException("Invalid Target type");
         }
     }
 
@@ -459,6 +488,23 @@ public void insertJson(MessageContext synCtx, Object sourceJsonElement, SynapseL
                 }
                 break;
             }
+            case EnrichMediator.VARIABLE:
+                if (action.equalsIgnoreCase(ACTION_REPLACE)) {
+                    String key = variable.evaluateValue(synCtx);
+                    if (StringUtils.isEmpty(key)) {
+                        synLog.error("Variable key cannot be null");
+                        return;
+                    }
+                    Map<String, Object> result = new HashMap<>();
+                    result.put(ExpressionConstants.PAYLOAD, sourceJsonElement);
+                    Map transportHeaders = (Map)((Axis2MessageContext) synCtx).getAxis2MessageContext()
+                            .getProperty(org.apache.axis2.context.MessageContext.TRANSPORT_HEADERS);
+                    JsonObject headers = EIPUtils.convertMapToJsonObj(transportHeaders);
+                    result.put(ExpressionConstants.HEADERS, headers);
+                    result.put(ExpressionConstants.ATTRIBUTES, CallMediatorEnrichUtil.populateTransportAttributes(synCtx));
+                    synCtx.setVariable(key, result);
+                }
+                break;
             default: {
                 synLog.error("Case mismatch for type: " + targetType);
             }
@@ -683,6 +729,14 @@ public void setProperty(String property) {
         this.property = property;
     }
 
+    public void setVariable(Value variable) {
+        this.variable = variable;
+    }
+
+    public Value getVariable() {
+        return variable;
+    }
+
     public void setTargetType(int targetType) {
         this.targetType = targetType;
     }

modules/core/src/main/java/org/apache/synapse/util/CallMediatorEnrichUtil.java

@@ -37,6 +37,7 @@
 import org.apache.commons.logging.LogFactory;
 import org.apache.http.protocol.HTTP;
 import org.apache.synapse.MessageContext;
+import org.apache.synapse.SynapseConstants;
 import org.apache.synapse.SynapseException;
 import org.apache.synapse.SynapseLog;
 import org.apache.synapse.core.axis2.Axis2MessageContext;
@@ -58,6 +59,7 @@ public class CallMediatorEnrichUtil {
     public static final String ENVELOPE = "envelope";
     public static final String BODY = "body";
     public static final String INLINE = "inline";
+    public static final String VARIABLE = "variable";
 
     public static final String JSON_TYPE = "application/json";
     public static final String TEXT_TYPE = "text/plain";
@@ -75,6 +77,8 @@ public static int convertTypeToInt(String type) {
             return EnrichMediator.CUSTOM;
         } else if (type.equals(INLINE)) {
             return EnrichMediator.INLINE;
+        } else if (type.equals(VARIABLE)) {
+            return EnrichMediator.VARIABLE;
         }
         return -1;
     }
@@ -297,5 +301,25 @@ public static SynapseLog getLog(MessageContext synCtx) {
         return new MediatorLog(log, false, synCtx);
     }
 
+    /**
+     * Populates the transport attributes of the message context to a JSON object.
+     *
+     * @param synCtx The message context.
+     * @return The JSON object containing the transport attributes.
+     */
+    public static JsonObject populateTransportAttributes(MessageContext synCtx) {
+        JsonObject attributes = new JsonObject();
+        Object httpStatusCodeObj = ((Axis2MessageContext) synCtx).getAxis2MessageContext().getProperty(
+                SynapseConstants.HTTP_SC);
+        if (httpStatusCodeObj != null) {
+            if (httpStatusCodeObj instanceof String) {
+                attributes.addProperty("statusCode", (String) httpStatusCodeObj);
+            } else if (httpStatusCodeObj instanceof Integer) {
+                attributes.addProperty("statusCode", (Integer) httpStatusCodeObj);
+            }
+        }
+        return attributes;
+    }
+
 }
 

modules/core/src/main/java/org/apache/synapse/util/synapse/expression/ast/PayloadAccessNode.java

@@ -43,6 +43,8 @@
 import java.util.Map;
 import java.util.Optional;
 import java.util.Set;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
 
 /**
  * Represents a node in the AST that accesses a value in the payload or variable.
@@ -126,6 +128,33 @@ public ExpressionResult evaluate(EvaluationContext context, boolean isObjectValu
                 // if no expression just return variable
                 if (StringUtils.isEmpty(expressionToEvaluate)) {
                     result = variable;
+                } else if (variable instanceof Map) {
+                    if (StringUtils.isNotEmpty(expressionToEvaluate)) {
+                        expressionToEvaluate = expressionToEvaluate.startsWith(".") ? "var" + expressionToEvaluate
+                                : "var." + expressionToEvaluate;
+                    }
+                    String[] keyAndExpression = ExpressionUtils.extractVariableAndJsonPath(expressionToEvaluate);
+                    String key = keyAndExpression[0];
+                    String expression = keyAndExpression[1];
+                    if (StringUtils.isNotEmpty(expression)) {
+                        expression = expression.startsWith(".") ? "$" + expression : "$." + expression;
+                    }
+                    Object keyValue = ((Map) variable).get(key);
+                    if (keyValue == null) {
+                        throw new EvaluationException("Could not find key: " + key + " in the variable: " + variable);
+                    } else if (StringUtils.isEmpty(expression)) {
+                        result = keyValue;
+                    } else if (keyValue instanceof JsonElement) {
+                        try {
+                            result = JsonPath.parse(keyValue.toString()).read(expression);
+                        } catch (PathNotFoundException e) {
+                            // convert jsonPath error to native one
+                            throw new EvaluationException(e.getMessage());
+                        }
+                    } else {
+                        throw new EvaluationException("Could not evaluate JSONPath expression: " + expression
+                                + " on non-JSON object");
+                    }
                 } else {
                     expressionToEvaluate = expressionToEvaluate.startsWith(".") ? "$" + expressionToEvaluate
                             : "$." + expressionToEvaluate;

modules/core/src/main/java/org/apache/synapse/util/synapse/expression/constants/ExpressionConstants.java

@@ -78,4 +78,6 @@ public class ExpressionConstants {
 
     public static final String UNKNOWN = "unknown";
     public static final String VAULT_LOOKUP = "wso2:vault-lookup('";
+    public static final String HEADERS = "headers";
+    public static final String ATTRIBUTES = "attributes";
 }

modules/core/src/test/java/org/apache/synapse/util/synapse/expression/PayloadAndVariableAccessTest.java

@@ -147,5 +147,11 @@ public void testVariableAccess() {
                 "var.random", 0, 1));
         Assert.assertEquals("", TestUtils.evaluateExpressionWithPayloadAndVariables(
                 "var.num1[0]", 0, 1));
+        Assert.assertEquals("201", TestUtils.evaluateExpressionWithPayloadAndVariables(
+                "var.fileRead_1.['attributes'].statusCode", 0, 3));
+        Assert.assertEquals("101", TestUtils.evaluateExpressionWithPayloadAndVariables(
+                "var[\"fileRead_1\"][\"headers\"]['Content-Length']", 0, 3));
+        Assert.assertEquals("[\"Moby Dick\",\"To Kill a Mockingbird\"]", TestUtils.evaluateExpressionWithPayloadAndVariables(
+                "var.fileRead_1['payload'][\"store\"][\"book\"][1,3].title", 2, 3));
     }
 }

modules/core/src/test/java/org/apache/synapse/util/synapse/expression/TestUtils.java

@@ -18,6 +18,7 @@
 
 package org.apache.synapse.util.synapse.expression;
 
+import com.google.gson.JsonObject;
 import com.google.gson.JsonParser;
 import org.antlr.v4.runtime.CharStream;
 import org.antlr.v4.runtime.CharStreams;
@@ -97,12 +98,18 @@ public class TestUtils {
             "  \"selectedCategory\": \"biography\"\n" +
             "}\n";
 
+    private static final JsonObject responseHeaders;
+
+    private static final JsonObject responseAttributes;
+
     private static final String PAYLOAD3 = "[\"When\",\"my\",\"time\",\"comes\",\"Forget\",\"the\",\"wrong\",\"that\"" +
             ",\"I've\",\"done\"]";
     private static final Map<String, Object> variableMap1;
 
     private static final Map<String, Object> variableMap2;
 
+    private static final Map<String, Object> variableMap3;
+
     static {
         variableMap1 = new HashMap<>();
         variableMap1.put("name", "John");
@@ -119,6 +126,18 @@ public class TestUtils {
         variableMap2.put("json1", PAYLOAD1);
         variableMap2.put("json2", PAYLOAD2);
         variableMap2.put("json3", "[1,2,3,\"abc\"]");
+        variableMap3 = new HashMap<>();
+        responseHeaders = new JsonObject();
+        responseHeaders.addProperty("Content-Type", "application/json");
+        responseHeaders.addProperty("Content-Length", "101");
+        responseAttributes = new JsonObject();
+        responseAttributes.addProperty("statusCode", 201);
+        Map<String, Object> result = new HashMap<>();
+        result.put("headers", responseHeaders);
+        result.put("attributes", responseAttributes);
+        result.put("payload", JsonParser.parseString(PAYLOAD2));
+        variableMap3.put("fileRead_1", result);
+
         try {
             synCtx = org.apache.synapse.mediators.TestUtils.getAxis2MessageContext("<test/>", null);
         } catch (Exception e) {
@@ -151,6 +170,10 @@ public static String evaluateExpressionWithPayloadAndVariables(String expression
                 for (Map.Entry<String, Object> entry : variableMap2.entrySet()) {
                     synCtx.setVariable(entry.getKey(), entry.getValue());
                 }
+            } else if (variableMapId == 3) {
+                for (Map.Entry<String, Object> entry : variableMap3.entrySet()) {
+                    synCtx.setVariable(entry.getKey(), entry.getValue());
+                }
             }
             SynapseExpression synapsePath = new SynapseExpression(expression);
             return synapsePath.stringValueOf(synCtx);