Pass default parser to custom parse value function (#218)

* Pass builtin parse method to parseValue function

* Update README.md

Author: Chris-James

README.md

@@ -91,7 +91,7 @@ Looking for examples? Check out the Wiki: [json-2-csv Wiki](https://github.com/m
       * `[ 'key1', 'key2', ... ]`
       * `[ { field: 'key1', title: 'Key 1' }, { field: 'key2' }, 'key3', ... ]`
     * Key Paths - If you are converting a nested object (ie. {info : {name: 'Mike'}}), then set this to ['info.name']
-  * `parseValue` - Function - Specify how values should be converted into CSV format. This function is provided a single field value at a time and must return a `String`.
+  * `parseValue` - Function - Specify how values should be converted into CSV format. This function is provided a single field value at a time and must return a `String`. The built-in parsing method is provided as the second argument for cases where default parsing is preferred.
     * Default: A built-in method is used to parse out a variety of different value types to well-known formats.
     * Note: Using this option may override other options, including `useDateIso8601Format` and `useLocaleFormat`.
   * `prependHeader` - Boolean - Should the auto-generated header be prepended as the first line in the CSV?

lib/converter.d.ts

@@ -114,7 +114,10 @@ export interface IFullOptions extends ISharedOptions {
    * Specify how values should be converted into CSV format. This function is provided a single field value at a time and must return a `String`.
    * Note: Using this option may override other options, including `useDateIso8601Format` and `useLocaleFormat`.
    */
-  parseValue?: (fieldValue: any) => string;
+  parseValue?: (
+    fieldValue: any,
+    defaultParser: (fieldValue: any) => string
+  ) => string;
 }
 
 export function json2csv(data: object[],

lib/json2csv.js

@@ -8,7 +8,7 @@ let path = require('doc-path'),
 const Json2Csv = function(options) {
     const wrapDelimiterCheckRegex = new RegExp(options.delimiter.wrap, 'g'),
         crlfSearchRegex = /\r?\n|\r/,
-        valueParserFn = options.parseValue && typeof options.parseValue === 'function' ? options.parseValue : recordFieldValueToString,
+        customValueParser = options.parseValue && typeof options.parseValue === 'function' ? options.parseValue : null,
         expandingWithoutUnwinding = options.expandArrayObjects && !options.unwindArrays,
         deeksOptions = {
             expandArrayObjects: expandingWithoutUnwinding,
@@ -251,7 +251,7 @@ const Json2Csv = function(options) {
                 // Process the data in this record and return the
                 processedRecordData = recordFieldData.map((fieldValue) => {
                     fieldValue = trimRecordFieldValue(fieldValue);
-                    fieldValue = valueParserFn(fieldValue);
+                    fieldValue = customValueParser ? customValueParser(fieldValue, recordFieldValueToString) : recordFieldValueToString(fieldValue);
                     fieldValue = preventCsvInjection(fieldValue);
                     fieldValue = wrapFieldValueIfNecessary(fieldValue);
 

test/json2csv.js

@@ -647,6 +647,16 @@ function runTests(jsonTestData, csvTestData) {
                 });
             });
 
+            it('should pass the default value parser to custom value parser function when provided', (done) => {
+                converter.json2csv(jsonTestData.trimmedFields, (err, csv) => {
+                    if (err) done(err);
+                    csv.should.equal(csvTestData.trimmedFields);
+                    done();
+                }, {
+                    parseValue: (fieldValue, defaultParser) => defaultParser(fieldValue)
+                });
+            });
+
             it('should wrap boolean values in wrap delimiters, if specified', (done) => {
                 converter.json2csv(jsonTestData.emptyFieldValues, (err, csv) => {
                     if (err) done(err);