From ea4887c3c165aa74558e1a2f7cf989ca4051f723 Mon Sep 17 00:00:00 2001
From: Vitaliy Velikodniy <vitaliy@velikodniy.name>
Date: Sun, 13 Oct 2024 15:14:30 +0300
Subject: [PATCH] add keeping whitespaces option

---
 build.gradle                                         |  2 +-
 .../velikodniy/vitaliy/fixedlength/FixedLength.java  |  2 +-
 .../vitaliy/fixedlength/annotation/FixedField.java   |  8 ++++++++
 .../velikodniy/vitaliy/fixedlength/ParserTest.java   | 12 ++++++++++++
 .../velikodniy/vitaliy/fixedlength/StringHolder.java |  8 ++++++++
 5 files changed, 30 insertions(+), 2 deletions(-)
 create mode 100644 src/test/java/name/velikodniy/vitaliy/fixedlength/StringHolder.java

diff --git a/build.gradle b/build.gradle
index 28394ba..b2f9b1b 100644
--- a/build.gradle
+++ b/build.gradle
@@ -16,7 +16,7 @@ plugins {
 }
 
 group 'name.velikodniy.vitaliy'
-version '0.12'
+version '0.13'
 
 repositories {
     mavenLocal()
diff --git a/src/main/java/name/velikodniy/vitaliy/fixedlength/FixedLength.java b/src/main/java/name/velikodniy/vitaliy/fixedlength/FixedLength.java
index dd96b5a..1f8fee5 100644
--- a/src/main/java/name/velikodniy/vitaliy/fixedlength/FixedLength.java
+++ b/src/main/java/name/velikodniy/vitaliy/fixedlength/FixedLength.java
@@ -326,7 +326,7 @@ private boolean acceptFieldContent(String content, FixedField fieldAnnotation) {
         if (content == null) {
             return false;
         }
-        if (content.trim().isEmpty()) {
+        if (content.trim().isEmpty() && !fieldAnnotation.allowEmptyStrings()) {
             return false;
         }
         if (fieldAnnotation.ignore().isEmpty()) {
diff --git a/src/main/java/name/velikodniy/vitaliy/fixedlength/annotation/FixedField.java b/src/main/java/name/velikodniy/vitaliy/fixedlength/annotation/FixedField.java
index ab8f82a..7bc0ae8 100644
--- a/src/main/java/name/velikodniy/vitaliy/fixedlength/annotation/FixedField.java
+++ b/src/main/java/name/velikodniy/vitaliy/fixedlength/annotation/FixedField.java
@@ -57,4 +57,12 @@
      * @return pattern matching content to ignore
      */
     String ignore() default "";
+
+    /**
+     * Allows empty string as value, by default it is false.
+     * If true - values will be kept as is
+     * If false - value will be null
+     * @return allows empty string as value boolean
+     */
+    boolean allowEmptyStrings() default false;
 }
diff --git a/src/test/java/name/velikodniy/vitaliy/fixedlength/ParserTest.java b/src/test/java/name/velikodniy/vitaliy/fixedlength/ParserTest.java
index b03d754..28be9bd 100644
--- a/src/test/java/name/velikodniy/vitaliy/fixedlength/ParserTest.java
+++ b/src/test/java/name/velikodniy/vitaliy/fixedlength/ParserTest.java
@@ -230,4 +230,16 @@ void testParseMixedLineTypeCustomPredicate() throws FixedLengthException {
 
         assertEquals(2, parse.size());
     }
+
+    @Test
+    @DisplayName("Parse object with whitespaces preventing it to cast as null")
+    void testParseWhitespaceNonNull() throws FixedLengthException {
+
+        List<StringHolder> holders = new FixedLength<StringHolder>()
+                .registerLineType(StringHolder.class)
+                .parse(new ByteArrayInputStream("   some text to drop".getBytes()));
+
+        assertEquals(1, holders.size());
+        assertEquals("   ", holders.get(0).value);
+    }
 }
diff --git a/src/test/java/name/velikodniy/vitaliy/fixedlength/StringHolder.java b/src/test/java/name/velikodniy/vitaliy/fixedlength/StringHolder.java
new file mode 100644
index 0000000..a9c0eb3
--- /dev/null
+++ b/src/test/java/name/velikodniy/vitaliy/fixedlength/StringHolder.java
@@ -0,0 +1,8 @@
+package name.velikodniy.vitaliy.fixedlength;
+
+import name.velikodniy.vitaliy.fixedlength.annotation.FixedField;
+
+public class StringHolder {
+    @FixedField(offset = 1, length = 3, padding = Character.MIN_VALUE, allowEmptyStrings = true)
+    public String value;
+}