Add 'excludeKeys' option to json2csv. (#174)

README.md

@@ -64,6 +64,9 @@ Looking for examples? Check out the Wiki: [json-2-csv Wiki](https://github.com/m
   * `emptyFieldValue` - Any - Value that, if specified, will be substituted in for field values that are `undefined`, `null`, or an empty string.
     * Default: none
   * `excelBOM` - Boolean - Should a unicode character be prepended to allow Excel to open a UTF-8 encoded file with non-ASCII characters present.
+  * `excludeKeys` - Array - Specify the keys that should be excluded from the output.
+    * Default: `[]`
+    * Note: When used with `unwindArrays`, arrays present at excluded key paths will not be unwound.
   * `expandArrayObjects` - Boolean - Should objects in array values be deep-converted to CSV?
   	* Default: `false`
   	* Example:
@@ -82,7 +85,7 @@ Looking for examples? Check out the Wiki: [json-2-csv Wiki](https://github.com/m
   	* `false` uses the following keys:
   		* `['specifications']`
     * Note: This may result in CSV output that does not map back exactly to the original JSON. See #102 for more information.
-  * `keys` - Array - Specify the keys (as strings) that should be converted.
+  * `keys` - Array - Specify the keys that should be converted.
     * Default: These will be auto-detected from your data by default.
     * Keys can either be specified as a String representing the key path that should be converted, or as an Object with the `key` property specifying the path. When specifying keys as an Object, you can also optionally specify a `title` which will be used for that column in the header. The list specified can contain a combination of Objects and Strings. 
       * `[ 'key1', 'key2', ... ]`

lib/converter.d.ts

@@ -19,7 +19,7 @@ export interface ISharedOptions {
   excelBOM?: boolean;
 
   /**
-   * Specify the keys (as strings) that should be converted
+   * Specify the keys that should be converted
    *
    * * If you have a nested object (ie. {info : {name: 'Mike'}}), then set this to ['info.name']
    * * If you want all keys to be converted, then specify null or don't specify the option to utilize the default.
@@ -87,6 +87,11 @@ export interface IFullOptions extends ISharedOptions {
    * @default false
    */
   useDateIso8601Format?: boolean;
+
+  /**
+   * Specify the keys that should be excluded from the output.
+   */
+  excludeKeys?: string[];
 }
 
 export function json2csv(data: object[],

lib/json2csv.js

@@ -81,6 +81,19 @@ const Json2Csv = function(options) {
         }, 0);
     }
 
+    /**
+     * If so specified, this filters the detected key paths to exclude any keys that have been specified
+     * @param keyPaths {Array<String>}
+     * @returns {Array<String>} filtered key paths
+     */
+    function filterExcludedKeys(keyPaths) {
+        if (options.excludeKeys) {
+            return keyPaths.filter((keyPath) => !options.excludeKeys.includes(keyPath));
+        }
+
+        return keyPaths;
+    }
+
     /**
      * If so specified, this sorts the header field names alphabetically
      * @param fieldNames {Array<String>}
@@ -157,11 +170,13 @@ const Json2Csv = function(options) {
 
         if (options.keys && !options.unwindArrays) {
             return Promise.resolve(options.keys)
+                .then(filterExcludedKeys)
                 .then(sortHeaderFields);
         }
 
         return getFieldNameList(data)
             .then(processSchemas)
+            .then(filterExcludedKeys)
             .then(sortHeaderFields);
     }
 
@@ -202,7 +217,7 @@ const Json2Csv = function(options) {
 
                     // If keys were provided, set the headerFields to the provided keys:
                     if (options.keys) {
-                        params.headerFields = options.keys;
+                        params.headerFields = filterExcludedKeys(options.keys);
                     }
                     return params;
                 });

package.json

@@ -5,7 +5,7 @@
     },
     "name": "json-2-csv",
     "description": "A JSON to CSV and CSV to JSON converter that natively supports sub-documents and auto-generates the CSV heading.",
-    "version": "3.9.0",
+    "version": "3.10.0",
     "homepage": "https://mrodrig.github.io/json-2-csv",
     "repository": {
         "type": "git",

test/json2csv.js

@@ -544,6 +544,56 @@ function runTests(jsonTestData, csvTestData) {
                     ]
                 });
             });
+
+            it('should exclude specified keys from the output', (done) => {
+                // Change the features array to be empty
+                const updatedCsvPerOptions = csvTestData.arrayObjects.replace('features.cons,', '')
+                    .replace('"[""cost"",""time""]",', '')
+                    .replace(',,,', ',,');
+
+                converter.json2csv(jsonTestData.arrayObjects, (err, csv) => {
+                    if (err) done(err);
+                    csv.should.equal(updatedCsvPerOptions);
+                    done();
+                }, {
+                    expandArrayObjects: true,
+                    keys: ['name', 'features.name', 'features.pros', 'features.cons', 'downloads'],
+                    excludeKeys: ['features.cons']
+                });
+            });
+
+            it('should exclude specified keys from the output when unwinding arrays', (done) => {
+                const updatedCsv = csvTestData.unwind.replace(',data.options.name', '')
+                    .replace(/,MacBook (Pro|Air) \d+/g, '')
+                    .replace(/,(Super|Turbo)charger/g, '')
+                    // De-duplicate the lines since the field isn't unwound due to being excluded
+                    .replace('5cf7ca3616c91100018844af,Computers\n', '')
+                    .replace('5cf7ca3616c91100018844bf,Cars\n', '');
+
+                converter.json2csv(jsonTestData.unwind, (err, csv) => {
+                    if (err) done(err);
+                    csv.should.equal(updatedCsv);
+                    done();
+                }, {
+                    unwindArrays: true,
+                    excludeKeys: ['data.options.name', 'data.options']
+                });
+            });
+
+            it('should exclude specified deeply nested key from the output when unwinding arrays', (done) => {
+                const updatedCsv = csvTestData.unwind.replace(',data.options.name', '')
+                    .replace(/,MacBook (Pro|Air) \d+/g, '')
+                    .replace(/,(Super|Turbo)charger/g, '');
+
+                converter.json2csv(jsonTestData.unwind, (err, csv) => {
+                    if (err) done(err);
+                    csv.should.equal(updatedCsv);
+                    done();
+                }, {
+                    unwindArrays: true,
+                    excludeKeys: ['data.options.name']
+                });
+            });
         });
     });