[INLONG-10883][SDK] Transform SQL support InitCap function

fix bugs caused by wrong use of TransformFunction annotation

inlong-sdk/transform-sdk/src/main/java/org/apache/inlong/sdk/transform/process/function/InitCapFunction.java

@@ -32,7 +32,7 @@
  * description: initcap(string)--returns a new form of STRING with the first character of each word converted to
  * uppercase and the rest characters to lowercase
  */
-@TransformFunction(names = {"initcap, init_cap"})
+@TransformFunction(names = {"initcap", "init_cap"})
 public class InitCapFunction implements ValueParser {
 
     private ValueParser stringParser;
@@ -44,11 +44,15 @@ public InitCapFunction(Function expr) {
 
     @Override
     public Object parse(SourceData sourceData, int rowIndex, Context context) {
-        Object strObject = stringParser.parse(sourceData, rowIndex, context).toString();
+        Object strObject = stringParser.parse(sourceData, rowIndex, context);
+        if (strObject == null) {
+            return null;
+        }
         String str = OperatorTools.parseString(strObject);
         if (str == null) {
             return null;
         }
+
         StringBuilder result = new StringBuilder();
         boolean capitalizeNext = true;
         for (char c : str.toCharArray()) {
@@ -64,6 +68,7 @@ public Object parse(SourceData sourceData, int rowIndex, Context context) {
                 result.append(c);
             }
         }
+
         return result.toString();
     }
 }

inlong-sdk/transform-sdk/src/test/java/org/apache/inlong/sdk/transform/process/function/string/TestInitCapFunction.java

@@ -0,0 +1,42 @@
+package org.apache.inlong.sdk.transform.process.function.string;
+
+import org.apache.inlong.sdk.transform.decode.SourceDecoderFactory;
+import org.apache.inlong.sdk.transform.encode.SinkEncoderFactory;
+import org.apache.inlong.sdk.transform.pojo.TransformConfig;
+import org.apache.inlong.sdk.transform.process.TransformProcessor;
+import org.junit.Assert;
+import org.junit.Test;
+
+import java.util.HashMap;
+import java.util.List;
+
+public class TestInitCapFunction extends AbstractFunctionStringTestBase{
+    @Test
+    public void testInitCapFunction() throws Exception {
+        String transformSql = "select initcap(string1) from source";
+        TransformConfig config = new TransformConfig(transformSql);
+        TransformProcessor<String, String> processor = TransformProcessor
+                .create(config, SourceDecoderFactory.createCsvDecoder(csvSource),
+                        SinkEncoderFactory.createKvEncoder(kvSink));
+
+        // case1: initcap('hello world')
+        List<String> output1 = processor.transform("hello world", new HashMap<>());
+        Assert.assertEquals(1, output1.size());
+        Assert.assertEquals(output1.get(0), "result=Hello World");
+
+        // case2: initcap('apache inLong')
+        List<String> output2 = processor.transform("apache inLong", new HashMap<>());
+        Assert.assertEquals(1, output2.size());
+        Assert.assertEquals(output2.get(0), "result=Apache Inlong");
+
+        String transformSql2 = "select initcap(stringX) from source";
+        TransformConfig config2 = new TransformConfig(transformSql2);
+        TransformProcessor<String, String> processor2 = TransformProcessor
+                .create(config2, SourceDecoderFactory.createCsvDecoder(csvSource),
+                        SinkEncoderFactory.createKvEncoder(kvSink));
+        // case3: initcap(null)
+        List<String> output3 = processor2.transform("apache inLong", new HashMap<>());
+        Assert.assertEquals(1, output3.size());
+        Assert.assertEquals(output3.get(0), "result=null");
+    }
+}