Do not throw exceptions when resolving paths in ingest documents (ela…

…stic#84659)

docs/changelog/84659.yaml

@@ -0,0 +1,5 @@
+pr: 84659
+summary: Do not throw exceptions when resolving paths in ingest documents
+area: Ingest
+type: enhancement
+issues: []

server/src/main/java/org/elasticsearch/ingest/IngestDocument.java

@@ -94,17 +94,12 @@ public IngestDocument(Map<String, Object> sourceAndMetadata, Map<String, Object>
      * Returns the value contained in the document for the provided path
      * @param path The path within the document in dot-notation
      * @param clazz The expected class of the field value
-     * @return the value for the provided path if existing, null otherwise
+     * @return the value for the provided path if existing
      * @throws IllegalArgumentException if the path is null, empty, invalid, if the field doesn't exist
      * or if the field that is found at the provided path is not of the expected type.
      */
     public <T> T getFieldValue(String path, Class<T> clazz) {
-        FieldPath fieldPath = new FieldPath(path);
-        Object context = fieldPath.initialContext;
-        for (String pathElement : fieldPath.pathElements) {
-            context = resolve(pathElement, path, context);
-        }
-        return cast(path, context, clazz);
+        return getFieldValue(path, clazz, false);
     }
 
     /**
@@ -118,15 +113,19 @@ public <T> T getFieldValue(String path, Class<T> clazz) {
      * or if the field that is found at the provided path is not of the expected type.
      */
     public <T> T getFieldValue(String path, Class<T> clazz, boolean ignoreMissing) {
-        try {
-            return getFieldValue(path, clazz);
-        } catch (IllegalArgumentException e) {
-            if (ignoreMissing && hasField(path) != true) {
+        FieldPath fieldPath = new FieldPath(path);
+        Object context = fieldPath.initialContext;
+        for (String pathElement : fieldPath.pathElements) {
+            ResolveResult result = resolve(pathElement, path, context);
+            if (result.wasSuccessful) {
+                context = result.resolvedObject;
+            } else if (ignoreMissing && hasField(path) == false) {
                 return null;
             } else {
-                throw e;
+                throw new IllegalArgumentException(result.errorMessage);
             }
         }
+        return cast(path, context, clazz);
     }
 
     /**
@@ -287,7 +286,12 @@ public void removeField(String path) {
         FieldPath fieldPath = new FieldPath(path);
         Object context = fieldPath.initialContext;
         for (int i = 0; i < fieldPath.pathElements.length - 1; i++) {
-            context = resolve(fieldPath.pathElements[i], path, context);
+            ResolveResult result = resolve(fieldPath.pathElements[i], path, context);
+            if (result.wasSuccessful) {
+                context = result.resolvedObject;
+            } else {
+                throw new IllegalArgumentException(result.errorMessage);
+            }
         }
 
         String leafKey = fieldPath.pathElements[fieldPath.pathElements.length - 1];
@@ -325,34 +329,33 @@ public void removeField(String path) {
         );
     }
 
-    private static Object resolve(String pathElement, String fullPath, Object context) {
+    private static ResolveResult resolve(String pathElement, String fullPath, Object context) {
         if (context == null) {
-            throw new IllegalArgumentException("cannot resolve [" + pathElement + "] from null as part of path [" + fullPath + "]");
+            return ResolveResult.error("cannot resolve [" + pathElement + "] from null as part of path [" + fullPath + "]");
         }
         if (context instanceof Map<?, ?> map) {
             if (map.containsKey(pathElement)) {
-                return map.get(pathElement);
+                return ResolveResult.success(map.get(pathElement));
             }
-            throw new IllegalArgumentException("field [" + pathElement + "] not present as part of path [" + fullPath + "]");
+            return ResolveResult.error("field [" + pathElement + "] not present as part of path [" + fullPath + "]");
         }
         if (context instanceof List<?> list) {
             int index;
             try {
                 index = Integer.parseInt(pathElement);
             } catch (NumberFormatException e) {
-                throw new IllegalArgumentException(
-                    "[" + pathElement + "] is not an integer, cannot be used as an index as part of path [" + fullPath + "]",
-                    e
+                return ResolveResult.error(
+                    "[" + pathElement + "] is not an integer, cannot be used as an index as part of path [" + fullPath + "]"
                 );
             }
             if (index < 0 || index >= list.size()) {
-                throw new IllegalArgumentException(
+                return ResolveResult.error(
                     "[" + index + "] is out of bounds for array with length [" + list.size() + "] as part of path [" + fullPath + "]"
                 );
             }
-            return list.get(index);
+            return ResolveResult.success(list.get(index));
         }
-        throw new IllegalArgumentException(
+        return ResolveResult.error(
             "cannot resolve ["
                 + pathElement
                 + "] from object of type ["
@@ -892,4 +895,25 @@ private FieldPath(String path) {
         }
 
     }
+
+    private static class ResolveResult {
+        boolean wasSuccessful;
+        String errorMessage;
+        Object resolvedObject;
+
+        static ResolveResult success(Object resolvedObject) {
+            ResolveResult result = new ResolveResult();
+            result.wasSuccessful = true;
+            result.resolvedObject = resolvedObject;
+            return result;
+        }
+
+        static ResolveResult error(String errorMessage) {
+            ResolveResult result = new ResolveResult();
+            result.wasSuccessful = false;
+            result.errorMessage = errorMessage;
+            return result;
+
+        }
+    }
 }