Fix #90

Author: cowtowncoder

release-notes/CREDITS

@@ -45,3 +45,8 @@ sothmann@github)
 
 * Reported #83: Serializing List with null values leads to corrupt CSV
  (2.6.0)
+
+Jonathan Cheseaux (cheseaux@github)
+
+* Reported #90: Unexpected output with arrays starting with a null/empty element
+ (2.6.4)

release-notes/VERSION

@@ -4,6 +4,11 @@ Project: jackson-dataformat-csv
 === Releases ===
 ------------------------------------------------------------------------
 
+2.6.4 (not yet released)
+
+#90: Unexpected output with arrays starting with a null/empty element
+ (reported by Jonathan C)
+
 2.6.3 (12-Oct-2015)
 
 #91: Ensure that "too many columns" is recoverable

src/main/java/com/fasterxml/jackson/dataformat/csv/CsvGenerator.java

@@ -158,7 +158,19 @@ private Feature(boolean defaultState) {
      */
     protected int _arraySeparator = -1;
 
+    /**
+     * Accumulated contents of an array cell, if any
+     */
     protected StringBuilder _arrayContents;
+
+    /**
+     * Additional counter that indicates number of value entries in the
+     * array. Needed because `null` entries do not add content, but need
+     * to be separated by array cell separator
+     *
+     * @since 2.7
+     */
+    protected int _arrayElements;
 
     /*
     /**********************************************************
@@ -424,6 +436,7 @@ public final void writeStartArray() throws IOException
                 } else {
                     _arrayContents.setLength(0);
                 }
+                _arrayElements = 0;
             }
         } else if (_arraySeparator >= 0) {
             // also: no nested arrays, yet
@@ -863,16 +876,18 @@ protected void _handleFirstLine() throws IOException
     }
 
     protected void _addToArray(String value) {
-        if (_arrayContents.length() > 0) {
+        if (_arrayElements > 0) {
             _arrayContents.append((char) _arraySeparator);
         }
+        ++_arrayElements;
         _arrayContents.append(value);
     }
 
     protected void _addToArray(char[] value) {
-        if (_arrayContents.length() > 0) {
+        if (_arrayElements > 0) {
             _arrayContents.append((char) _arraySeparator);
         }
+        ++_arrayElements;
         _arrayContents.append(value);
     }
 }

src/test/java/com/fasterxml/jackson/dataformat/csv/deser/TestParserWorkarounds.java

@@ -27,7 +27,6 @@ public void testIgnoringOptionalTrailing() throws Exception
             .addColumn("second")
             .build();
 
-        @SuppressWarnings("resource")
         MappingIterator<Map<?,?>> it = mapper.reader(schema).forType(Map.class).readValues(
                 "a,b\nc,d,\ne,f,  \nfoo,bar,x\n");
         assertTrue(it.hasNext());
@@ -59,6 +58,7 @@ public void testIgnoringOptionalTrailing() throws Exception
         } catch (JsonParseException e) {
             verifyException(e, "Too many entries");
         }
+        it.close();
     }
 
     // also ensure [databind-csv#1] also works appropriately for failing case
@@ -70,7 +70,6 @@ public void testOptionalTrailFailing() throws Exception
             .addColumn("second")
             .build();
 
-        @SuppressWarnings("resource")
         MappingIterator<Map<?,?>> it = mapper.reader(schema).forType(Map.class).readValues(
                 "a,b,\nc,d,,,\n");
         assertTrue(it.hasNext());
@@ -88,5 +87,6 @@ public void testOptionalTrailFailing() throws Exception
         } catch (JsonProcessingException e) {
             verifyException(e, "Too many entries: expected at most 2");
         }
+        it.close();
     }
 }

src/test/java/com/fasterxml/jackson/dataformat/csv/ser/ArrayWriteTest.java

@@ -4,7 +4,8 @@
 
 import com.fasterxml.jackson.dataformat.csv.*;
 
-// for [dataformat-csv#57]
+// Tests for verifying that it is possible to write "simple" arrays
+// (ones with scalar serializations) as CSV
 public class ArrayWriteTest extends ModuleTestBase
 {
     @JsonPropertyOrder({"id", "values", "extra"})
@@ -19,6 +20,16 @@ public ValueEntry(String id, String extra, int... v) {
         }
     }
 
+    @JsonPropertyOrder({"a", "b", "c"})
+    static class Pojo90 {
+
+        public String[] a = new String[]{"", "foo"};
+
+        public String[] b = new String[]{null, "bar"};
+
+        public String[] c = new String[]{"baz",null};
+    }
+
     /*
     /**********************************************************************
     /* Test methods
@@ -49,4 +60,17 @@ public void testSeparatorOverride() throws Exception
         // gets quoted due to white space
         assertEquals("foo,\"1 2 3\",stuff", csv);
     }
+
+    public void testArraysWithNulls() throws Exception
+    {
+        Pojo90 value = new Pojo90();
+        CsvMapper mapper = mapperForCsv();
+        String csvContent = mapper.writer(mapper.schemaFor(Pojo90.class)
+                .withHeader())
+                .writeValueAsString(value);
+        String[] lines = csvContent.split("\\n");
+        assertEquals(2, lines.length);
+        assertEquals("a,b,c", lines[0]);
+        assertEquals(";foo,;bar,baz;", lines[1]);
+    }
 }