Fix #95

Author: cowtowncoder

avro/src/main/java/com/fasterxml/jackson/dataformat/avro/AvroSchema.java

@@ -90,6 +90,28 @@ public AvroSchema withReaderSchema(AvroSchema readerSchema)
         return Resolving.create(w, r);
     }
 
+    /**
+     * Similar to {@link #withReaderSchema} but will NOT verify compatibility of schemas:
+     * this means that certain problems (such as missing default value for a newly added
+     * field) that would be caught at construction may be surfaced later when using
+     * schema. This is, however, sometimes necessary to work around potential BUT NOT ACTUAL
+     * problems.
+     *
+     * @since 2.9
+     */
+    public AvroSchema withUnsafeReaderSchema(AvroSchema readerSchema)
+        throws JsonProcessingException
+    {
+        Schema w = _writerSchema;
+        Schema r = readerSchema.getAvroSchema();
+
+        if (r.equals(w)) {
+            return this;
+        }
+        w = Schema.applyAliases(w, r);
+        return Resolving.create(w, r);
+    }
+
     @Override
     public String getSchemaType() {
         return TYPE_ID;

avro/src/test/java/com/fasterxml/jackson/dataformat/avro/schemaev/SimpleEvolutionTest.java

@@ -179,5 +179,9 @@ public void testFailNewFieldNoDefault() throws Exception
             verifyException(e, "Data encoded using writer schema");
             verifyException(e, "will or may fail to decode using reader schema");
         }
+
+        // However... should be possible with unsafe alternative
+        AvroSchema risky = srcSchema.withUnsafeReaderSchema(dstSchema);
+        assertNotNull(risky);
     }
 }

release-notes/VERSION

@@ -11,6 +11,8 @@ Modules:
 
 2.9.0 (not yet released)
 
+#95: Add new method, `withUnsafeReaderSchema` in `AvroSchema` to allow avoiding verification exception
+
 2.8.9.1 (not yet released)
 
 #94: Should _ensureRoom in ProtobufGenerator.writeString()