Handle empty array case when unwindArrays option is true.

If an empty array was encountered when the unwindArrays option was set to true, the document was ignored and essentially was removed from the CSV output which is not the expected behavior. This commit addresses that bug by ensuring that the "unwound" version of the empty array is still pushed to the accumulator so the document is not excluded.

Fixes #151.

Author: mrodrig

src/utils.js

@@ -216,11 +216,15 @@ function unwindItem(accumulator, item, fieldPath) {
     const valueToUnwind = path.evaluatePath(item, fieldPath);
     let cloned = deepCopy(item);
 
-    if (Array.isArray(valueToUnwind)) {
+    if (Array.isArray(valueToUnwind) && valueToUnwind.length) {
         valueToUnwind.forEach((val) => {
             cloned = deepCopy(item);
             accumulator.push(path.setPath(cloned, fieldPath, val));
         });
+    } else if (Array.isArray(valueToUnwind) && valueToUnwind.length === 0) {
+        // Push an empty string so the value is empty since there are no values
+        path.setPath(cloned, fieldPath, '');
+        accumulator.push(cloned);
     } else {
         accumulator.push(cloned);
     }

test/config/testCsvFilesList.js

@@ -30,6 +30,7 @@ const fs = require('fs'),
         {key: 'quotedEmptyFieldValue', file: '../data/csv/quotedEmptyFieldValue.csv'},
         {key: 'csvEmptyLastValue', file: '../data/csv/csvEmptyLastValue.csv'},
         {key: 'unwind', file: '../data/csv/unwind.csv'},
+        {key: 'unwindEmptyArray', file: '../data/csv/unwindEmptyArray.csv'},
         {key: 'unwindWithSpecifiedKeys', file: '../data/csv/unwindWithSpecifiedKeys.csv'},
         {key: 'localeFormat', file: '../data/csv/localeFormat.csv'},
         {key: 'invalidParsedValues', file: '../data/csv/invalidParsedValues.csv'}

test/config/testJsonFilesList.js

@@ -23,6 +23,7 @@ module.exports = {
     quotedEmptyFieldValue: require('../data/json/quotedEmptyFieldValue'),
     csvEmptyLastValue: require('../data/json/csvEmptyLastValue'),
     unwind: require('../data/json/unwind'),
+    unwindEmptyArray: require('../data/json/unwindEmptyArray'),
     localeFormat: require('../data/json/localeFormat'),
     invalidParsedValues: require('../data/json/invalidParsedValues')
 };

test/data/csv/unwindEmptyArray.csv

@@ -0,0 +1,4 @@
+_id.$oid,data.category,data.options
+5cf7ca3616c91100018844af,Computers,
+5cf7ca3616c91100018844bf,Cars,Supercharger
+5cf7ca3616c91100018844bf,Cars,Turbocharger

test/data/json/unwindEmptyArray.json

@@ -0,0 +1,10 @@
+[
+  {
+    "_id": {"$oid": "5cf7ca3616c91100018844af"},
+    "data": {"category": "Computers", "options": []}
+  },
+  {
+    "_id": {"$oid": "5cf7ca3616c91100018844bf"},
+    "data": {"category": "Cars", "options": ["Supercharger", "Turbocharger"]}
+  }
+]

test/json2csv.js

@@ -415,6 +415,16 @@ function runTests(jsonTestData, csvTestData) {
                 });
             });
 
+            it('should handle unwinding empty array values when specified', (done) => {
+                converter.json2csv(jsonTestData.unwindEmptyArray, (err, csv) => {
+                    if (err) done(err);
+                    csv.should.equal(csvTestData.unwindEmptyArray);
+                    done();
+                }, {
+                    unwindArrays: true
+                });
+            });
+
             it('should unwind array values when specified', (done) => {
                 converter.json2csv(jsonTestData.unwind, (err, csv) => {
                     if (err) done(err);