[jOOQ/jOOQ#15085] Confusing error message when reading a non-existing

Field from a Record containing accidentally nested row types

jOOQ/src/main/java/org/jooq/impl/AbstractRecord.java

@@ -386,7 +386,7 @@ implements
         if (index >= 0 && index < values.length)
             return index;
 
-        throw new IllegalArgumentException("No field at index " + index + " in Record type " + fields);
+        throw indexFail(fields, index);
     }
 
     /**

jOOQ/src/main/java/org/jooq/impl/FieldsImpl.java

@@ -38,9 +38,11 @@
 
 package org.jooq.impl;
 
+import static org.jooq.impl.DSL.row;
 import static org.jooq.impl.QueryPartListView.wrap;
 import static org.jooq.impl.Tools.EMPTY_FIELD;
 import static org.jooq.impl.Tools.converterOrFail;
+import static org.jooq.impl.Tools.indexFail;
 import static org.jooq.impl.Tools.indexOrFail;
 import static org.jooq.impl.Tools.map;
 import static org.jooq.impl.Tools.newRecord;
@@ -78,7 +80,14 @@ import org.jooq.tools.JooqLogger;
  *
  * @author Lukas Eder
  */
-final class FieldsImpl<R extends Record> extends AbstractQueryPart implements RecordType<R>, Mappable<R>, UTransient {
+final class FieldsImpl<R extends Record>
+extends
+    AbstractQueryPart
+implements
+    RecordType<R>,
+    Mappable<R>,
+    UTransient
+{
 
     private static final JooqLogger log = JooqLogger.getLogger(FieldsImpl.class);
     Field<?>[]                      fields;
@@ -407,7 +416,7 @@ final class FieldsImpl<R extends Record> extends AbstractQueryPart implements Re
         if (index >= 0 && index < fields.length)
             return index;
 
-        throw new IllegalArgumentException("No field at index " + index + " in Record type " + fields);
+        throw indexFail(this, index);
     }
 
     @Override
@@ -660,4 +669,9 @@ final class FieldsImpl<R extends Record> extends AbstractQueryPart implements Re
     public int hashCode() {
         return Arrays.hashCode(fields);
     }
+
+    @Override
+    public String toString() {
+        return row(fields).toString();
+    }
 }

jOOQ/src/main/java/org/jooq/impl/ResultImpl.java

@@ -40,6 +40,7 @@ package org.jooq.impl;
 
 import static org.jooq.Records.intoList;
 import static org.jooq.Records.intoResultGroups;
+import static org.jooq.impl.Tools.indexFail;
 import static org.jooq.impl.Tools.indexOrFail;
 
 import java.lang.reflect.Array;
@@ -1068,7 +1069,7 @@ final class ResultImpl<R extends Record> extends AbstractResult<R> implements Re
         if (index >= 0 && index < fields.size())
             return index;
 
-        throw new IllegalArgumentException("No field at index " + index + " in Record type " + fields);
+        throw indexFail(fields, index);
     }
 
     // -------------------------------------------------------------------------

jOOQ/src/main/java/org/jooq/impl/Tools.java

@@ -2238,7 +2238,26 @@ final class Tools {
     }
 
     static final IllegalArgumentException indexFail(Fields row, Field<?> field) {
-        return new IllegalArgumentException("Field (" + field + ") is not contained in Row " + row);
+        if (lookupNested(row, field))
+            return new IllegalArgumentException("Field " + field + " is not contained at the top level of row type containing nested row types. Unnest the nested row type first and access the field from there: " + row);
+        else
+            return new IllegalArgumentException("Field " + field + " is not contained in row type " + row);
+    }
+
+    private static final boolean lookupNested(Fields row, Field<?> field) {
+
+        // [#15085] [#16721] Help users spot the problem if they accidentally nest row types
+        if (row.field(field) != null)
+            return true;
+
+        for (Field<?> f : row.fields()) {
+            if (f instanceof AbstractRowAsField<?> rf) {
+                if (lookupNested(rf.fields0(), field))
+                    return true;
+            }
+        }
+
+        return false;
     }
 
     static final int indexOrFail(Fields row, Field<?> field) {
@@ -2251,7 +2270,7 @@ final class Tools {
     }
 
     static final IllegalArgumentException indexFail(Fields row, String fieldName) {
-        throw new IllegalArgumentException("Field (" + fieldName + ") is not contained in Row " + row);
+        return indexFail(row, DSL.name(fieldName));
     }
 
     static final int indexOrFail(Fields row, String fieldName) {
@@ -2264,7 +2283,7 @@ final class Tools {
     }
 
     static final IllegalArgumentException indexFail(Fields row, Name fieldName) {
-        throw new IllegalArgumentException("Field (" + fieldName + ") is not contained in Row " + row);
+        return indexFail(row, DSL.field(fieldName));
     }
 
     static final int indexOrFail(Fields row, Name fieldName) {
@@ -2277,7 +2296,23 @@ final class Tools {
     }
 
     static final IllegalArgumentException indexFail(Fields row, int fieldIndex) {
-        throw new IllegalArgumentException("Field (" + fieldIndex + ") is not contained in Row " + row);
+        if (fieldIndex < countFlattened(row, 0))
+            return new IllegalArgumentException("No field at index " + fieldIndex + " is not contained at the top level of row type containing nested row types. Unnest the nested row types first and access the field from there: " + row);
+        else
+            return new IllegalArgumentException("No field at index " + fieldIndex + " in row type " + row);
+    }
+
+    private static final int countFlattened(Fields row, int count) {
+
+        // [#15085] [#16721] Help users spot the problem if they accidentally nest row types
+        for (Field<?> f : row.fields()) {
+            if (f instanceof AbstractRowAsField<?> rf)
+                count += countFlattened(rf.fields0(), count);
+            else
+                count++;
+        }
+
+        return count;
     }
 
     static final int indexOrFail(Fields row, int fieldIndex) {