Added flag to signal if resulting function value should be stringified or not

README.md

@@ -92,7 +92,8 @@ try {
         // data = full data object
         return row.path1 + row.path2;
       },
-      default: 'NULL' // default if value function returns null or undefined
+      default: 'NULL', // default if value function returns null or undefined
+      stringify: true // If value is function use this flag to signal if resulting string will be quoted (stringified) or not (optional, default: true)
     },
 
     // Support pathname -> pathvalue

lib/json2csv.js

@@ -215,6 +215,7 @@ function createColumnContent(params, str) {
       params.fields.forEach(function (fieldElement) {
         var val;
         var defaultValue = params.defaultValue;
+        var stringify = true;
         if (typeof fieldElement === 'object' && 'default' in fieldElement) {
           defaultValue = fieldElement.default;
         }
@@ -228,6 +229,9 @@ function createColumnContent(params, str) {
             default: fieldElement.default
           };
           val = fieldElement.value(dataElement, field, params.data);
+          if (fieldElement.stringify !== undefined) {
+            stringify = fieldElement.stringify;
+          }
         }
 
         if (val === null || val === undefined){
@@ -241,7 +245,10 @@ function createColumnContent(params, str) {
               .replace(/\r/g, '\u2029');
           }
 
-          var stringifiedElement = JSON.stringify(val);
+          var stringifiedElement = val;
+          if (stringify) {
+            stringifiedElement = JSON.stringify(val);
+          }
 
           if (params.preserveNewLinesInValues && typeof val === 'string') {
             stringifiedElement = stringifiedElement

test/fixtures/csv/functionNoStringify.csv

@@ -0,0 +1,3 @@
+"Value1"
+"abc"
+1234

test/fixtures/csv/functionStringifyByDefault.csv

@@ -0,0 +1,3 @@
+"Value1"
+"abc"
+"1234"

test/helpers/load-fixtures.js

@@ -23,6 +23,8 @@ var fixtures = [
   'embeddedjson',
   'flattenedEmbeddedJson',
   'fancyfields',
+  'functionStringifyByDefault',
+  'functionNoStringify',
   'trailingBackslash',
   'excelStrings',
   'overriddenDefaultValue',

test/index.js

@@ -408,6 +408,47 @@ async.parallel(loadFixtures(csvFixtures), function (err) {
     });
   });
 
+  test('function value should stringify results by default', function (t) {
+    json2csv({
+      data: [{
+        value1: 'abc'
+      }, {
+        value1: '1234'
+      }],
+      fields: [{
+        label: 'Value1',
+        value: function (row) {
+          return row.value1.toLocaleString();
+        }
+      }]
+    }, function (error, csv) {
+      t.error(error);
+      t.equal(csv, csvFixtures.functionStringifyByDefault);
+      t.end();
+    });
+  });
+
+  test('function value do not stringify', function (t) {
+    json2csv({
+      data: [{
+        value1: '"abc"'
+      }, {
+        value1: '1234'
+      }],
+      fields: [{
+        label: 'Value1',
+        value: function (row) {
+          return row.value1.toLocaleString();
+        },
+        stringify: false
+      }]
+    }, function (error, csv) {
+      t.error(error);
+      t.equal(csv, csvFixtures.functionNoStringify);
+      t.end();
+    });
+  });
+
   test('should parse JSON values with trailing backslashes', function (t) {
     json2csv({
       data: jsonTrailingBackslash,