Improve error message when JSON parser finds an object where an array is expected

hapi-fhir-base/src/main/java/ca/uhn/fhir/parser/JsonParser.java

@@ -1014,7 +1014,7 @@ public class JsonParser extends BaseParser implements IParser {
 			if ("resourceType".equals(nextName)) {
 				continue;
 			} else if ("entry".equals(nextName)) {
-				JsonArray entries = theObject.getJsonArray(nextName);
+				JsonArray entries = grabJsonArray(theObject, nextName, "entry");
 				for (JsonValue jsonValue : entries) {
 					theState.enteringNewElement(null, "entry");
 					parseBundleChildren((JsonObject) jsonValue, theState);
@@ -1023,7 +1023,7 @@ public class JsonParser extends BaseParser implements IParser {
 				continue;
 			} else if (myContext.getVersion().getVersion() == FhirVersionEnum.DSTU1) {
 				if ("link".equals(nextName)) {
-					JsonArray entries = theObject.getJsonArray(nextName);
+					JsonArray entries = grabJsonArray(theObject, nextName, "link");
 					for (JsonValue jsonValue : entries) {
 						theState.enteringNewElement(null, "link");
 						JsonObject linkObj = (JsonObject) jsonValue;
@@ -1042,7 +1042,7 @@ public class JsonParser extends BaseParser implements IParser {
 				}
 			} else {
 				if ("link".equals(nextName)) {
-					JsonArray entries = theObject.getJsonArray(nextName);
+					JsonArray entries = grabJsonArray(theObject, nextName, "link");
 					for (JsonValue jsonValue : entries) {
 						theState.enteringNewElement(null, "link");
 						JsonObject linkObj = (JsonObject) jsonValue;
@@ -1106,11 +1106,11 @@ public class JsonParser extends BaseParser implements IParser {
 				}
 				continue;
 			} else if ("extension".equals(nextName)) {
-				JsonArray array = theObject.getJsonArray(nextName);
+				JsonArray array = grabJsonArray(theObject, nextName, "extension");
 				parseExtension(theState, array, false);
 				continue;
 			} else if ("modifierExtension".equals(nextName)) {
-				JsonArray array = theObject.getJsonArray(nextName);
+				JsonArray array = grabJsonArray(theObject, nextName, "modifierExtension");
 				parseExtension(theState, array, true);
 				continue;
 			} else if (nextName.charAt(0) == '_') {
@@ -1135,6 +1135,17 @@ public class JsonParser extends BaseParser implements IParser {
 		}
 	}
 
+	private JsonArray grabJsonArray(JsonObject theObject, String nextName, String thePosition) {
+		JsonValue object = theObject.get(nextName);
+		if (object == null) {
+			return null;
+		}
+		if (object.getValueType() != ValueType.ARRAY) {
+			throw new DataFormatException("Syntax error parsing JSON FHIR structure: Expected ARRAY at element '" + thePosition + "', found '" + object.getValueType().name() + "'");
+		}
+		return (JsonArray) object;
+	}
+
 	private void parseChildren(ParserState<?> theState, String theName, JsonValue theJsonVal, JsonValue theAlternateVal, String theAlternateName) {
 		switch (theJsonVal.getValueType()) {
 		case ARRAY: {

hapi-fhir-structures-dstu2/src/test/java/ca/uhn/fhir/parser/JsonParserDstu2Test.java

@@ -28,6 +28,7 @@ import ca.uhn.fhir.model.dstu2.composite.HumanNameDt;
 import ca.uhn.fhir.model.dstu2.composite.ResourceReferenceDt;
 import ca.uhn.fhir.model.dstu2.resource.Binary;
 import ca.uhn.fhir.model.dstu2.resource.Bundle.Entry;
+import ca.uhn.fhir.model.dstu2.resource.Conformance;
 import ca.uhn.fhir.model.dstu2.resource.DiagnosticReport;
 import ca.uhn.fhir.model.dstu2.resource.Medication;
 import ca.uhn.fhir.model.dstu2.resource.MedicationOrder;
@@ -474,17 +475,6 @@ public class JsonParserDstu2Test {
 		assertThat(ourCtx.newJsonParser().setOmitResourceId(true).encodeResourceToString(p), not(containsString("123")));
 	}
 
-	@Test
-	public void testParseAndEncodeBundleResourceWithComments() throws Exception {
-		String content = IOUtils.toString(JsonParserDstu2Test.class.getResourceAsStream("/bundle-transaction2.json"));
-
-		ourCtx.newJsonParser().parseBundle(content);
-		
-		ca.uhn.fhir.model.dstu2.resource.Bundle parsed = ourCtx.newJsonParser().parseResource(ca.uhn.fhir.model.dstu2.resource.Bundle.class, content);
-		
-		// TODO: preserve comments
-	}
-	
 	@Test
 	public void testParseAndEncodeBundle() throws Exception {
 		String content = IOUtils.toString(JsonParserDstu2Test.class.getResourceAsStream("/bundle-example.json"));
@@ -641,6 +631,17 @@ public class JsonParserDstu2Test {
 
 	}
 
+	@Test
+	public void testParseAndEncodeBundleResourceWithComments() throws Exception {
+		String content = IOUtils.toString(JsonParserDstu2Test.class.getResourceAsStream("/bundle-transaction2.json"));
+
+		ourCtx.newJsonParser().parseBundle(content);
+		
+		ca.uhn.fhir.model.dstu2.resource.Bundle parsed = ourCtx.newJsonParser().parseResource(ca.uhn.fhir.model.dstu2.resource.Bundle.class, content);
+		
+		// TODO: preserve comments
+	}
+
 	@Test
 	public void testParseAndEncodeBundleWithDeletedEntry() {
 
@@ -917,6 +918,17 @@ public class JsonParserDstu2Test {
 		}
 	}
 
+	@Test
+	public void testParseWithWrongTypeObjectShouldBeArray() throws Exception {
+		String input = IOUtils.toString(getClass().getResourceAsStream("/invalid_metadata.json"));
+		try {
+			ourCtx.newJsonParser().parseResource(Conformance.class, input);
+			fail();
+		} catch (DataFormatException e) {
+			assertEquals("Syntax error parsing JSON FHIR structure: Expected ARRAY at element 'modifierExtension', found 'OBJECT'", e.getMessage());
+		}
+	}
+
 	/**
 	 * See #144 and #146
 	 */

hapi-fhir-structures-dstu2/src/test/resources/invalid_metadata.json

@@ -0,0 +1,65 @@
+{
+  "resourceType": "Conformance",
+  "meta": {
+    "versionId": "0.0.1"
+  },
+  "status": "draft",
+  "experimental": true,
+  "date": "2015-09-23T12:00:00Z",
+  "fhirVersion": "DSTU 2 0.5.0",
+  "acceptUnknown": false,
+  "format": [
+    "json"
+  ],
+  "rest": [
+    {
+      "mode": "server",
+      "documentation": "Information about the system's restful capabilities that apply across all applications, such as security",
+      "security": {
+        "cors": false,
+        "service": [
+          {
+            "coding": [
+              {
+                "system": "http://hl7.org/fhir/restful-security-service",
+                "code": "OAuth"
+              }
+            ]
+          }
+        ],
+        "description": "General description of how security works",
+        "certificate": [
+          {
+            "type": "json"
+          }
+        ],
+        "modifierExtension": {
+          "url": "http://fhir-registry.smarthealthit.org/StructureDefinition/oauth-uris"
+        },
+        "extension": {
+          "url": "http://fhir-registry.smarthealthit.org/StructureDefinition/oauth-uris"
+        }
+      },
+      "resource": [
+        {
+          "type": "Patient",
+          "profile": {
+            "reference": "http://hl7.org/fhir/StructureDefinition/patient-daf-dafpatient"
+          },
+          "interaction": [
+            {
+              "code": "read"
+            },
+            {
+              "code": "update"
+            },
+            {
+              "code": "search-type"
+            }
+          ],
+          "versioning": "no-version"
+        }
+      ]
+    }
+  ]
+}

src/changes/changes.xml

@@ -37,6 +37,10 @@
 				Constructor for DateRanfeParam which dates in two DateParam instances was ignoring 
 				comparators on the DateParam.
 			</action>
+			<action type="fix">
+				In JSON parsing, finding an object where an array was expected led to an unhelpful
+				error message. Thanks to Avinash Shanbhag for reporting!
+			</action>
 		</release>
 		<release version="1.2" date="2015-09-18">
 			<action type="add">