added a csv.generate function

Readme.md

@@ -69,6 +69,16 @@ res.csv([ { name: "joe", id: 1 }]
 //=> "joe", 1
 ```
 
+csv also expose a generate() function that generate a csv string from an array, E.g:
+
+```js
+var csvString = csv.generate([
+    ["a", "b", "c"]
+  , ["d", "e", "f"]
+  ]);
+// => csvString = '"a", "b", "c"\n"d", "e", "f"'
+```
+
 ## License
 
     The MIT License

lib/express-csv.js

@@ -82,6 +82,23 @@ function objToArray(obj) {
   return result;
 }
 
+/**
+ * Generate a csv string fom an object
+ *
+ * @param {Array} obj
+ * @return {String}
+*/
+
+exports.generate = function(obj) {
+  var str = '';
+  obj.forEach(function(item) {
+    if (!(item instanceof Array)) item = objToArray(item);
+    str += item.map(escape).join(exports.separator) + '\r\n';
+  });
+  return str;
+};
+
+
 /**
  * Send CSV response with `obj`, optional `headers`, and optional `status`.
  * 
@@ -93,16 +110,11 @@ function objToArray(obj) {
  */
 
 res.csv = function(obj, headers, status) {
-  var body = '';
+  var body = exports.generate(obj);
 
   this.charset = this.charset || 'utf-8';
   this.header('Content-Type', 'text/csv');
 
-  obj.forEach(function(item) {
-    if (!(item instanceof Array)) item = objToArray(item);
-    body += item.map(escape).join(exports.separator) + '\r\n';
-  });
-
   return this.send(body, headers, status);
 };
 

test/index.js

@@ -3,30 +3,35 @@ var express = require('express')
   , csv = require('../')
   , app = express.createServer();
 
+var test1Data = [
+      ['a', 'b', 'c']
+    , ['d', 'e', 'f']
+    ]
+  , test2Data = [
+    [ 'a', 'b', null ]
+  ]
+  , test3Data = [
+      [ 'a', 'b', undefined ]
+    ]
+  , testObjectArrayData = [
+      { stringProp: "a", nullProp: null, undefinedProp: undefined },
+      { stringProp: "b", nullProp: null, undefinedProp: undefined }
+    ];
+
 app.get('/test/1', function(req, res) {
-  res.csv([
-    ['a', 'b', 'c']
-  , ['d', 'e', 'f']
-  ]);
+  res.csv(test1Data);
 });
 
 app.get('/test/2', function(req, res) {
-  res.csv([
-    [ 'a', 'b', null ]
-  ]);
+  res.csv(test2Data);
 });
 
 app.get('/test/3', function(req, res) {
-  res.csv([
-    [ 'a', 'b', undefined ]
-  ]);
+  res.csv(test3Data);
 });
 
 app.get('/test/objectArray', function(req, res) {
-  res.csv([
-    { stringProp: "a", nullProp: null, undefinedProp: undefined },
-    { stringProp: "b", nullProp: null, undefinedProp: undefined }
-  ]);
+  res.csv(testObjectArrayData);
 });
 
 app.listen(8383);
@@ -37,28 +42,131 @@ describe('express-csv', function() {
   });
 
   it('should expose .separator', function() {
-    csv.separator.should.be.a('string');
+    csv.separator.should.be.type('string');
   });
 
   it('should expose .preventCast', function() {
-    csv.preventCast.should.be.a('boolean');
+    csv.preventCast.should.be.type('boolean');
   });
 
   it('should expose .ignoreNullOrUndefined', function() {
-    csv.ignoreNullOrUndefined.should.be.a('boolean');
+    csv.ignoreNullOrUndefined.should.be.type('boolean');
+  });
+
+  it('should expose .generate()', function() {
+    csv.generate.should.be.type('function');
   });
 
   it('should extend res.csv', function() {
     if (express.version.match(/^2\.[0-9]+\.[0-9]+$/)) {
       // express 2.x
-      require('http').ServerResponse.prototype.csv.should.be.a('function');
+      require('http').ServerResponse.prototype.csv.should.be.type('function');
     } else {
       // express 3.x
-      require('express').response.csv.should.be.a('function');
+      require('express').response.csv.should.be.type('function');
     }
   });
 });
 
+describe('csv.generate()', function() {
+  describe('when given an array of objects', function() {
+    describe('and ignoreNullOrUndefined is true', function() {
+      var rows;
+
+      beforeEach(function() {
+        console.log(csv.generate(testObjectArrayData));
+        rows = csv.generate(testObjectArrayData).split("\r\n");
+      });
+
+      it('should include values that exist', function() {
+        rows[0].split(",")[0].should.equal('"a"');
+        rows[1].split(",")[0].should.equal('"b"');
+      });
+
+      it('should exclude null', function() {
+        rows[0].split(",")[1].should.equal('');
+        rows[0].split(",")[2].should.equal('');
+      });
+
+      it('should exclude undefined', function() {
+        rows[0].split(",")[2].should.equal('');
+        rows[1].split(",")[2].should.equal('');
+      });
+
+
+      describe('and ignoreNullOrUndefined is false', function() {
+        var rows;
+
+        beforeEach(function() {
+          csv.ignoreNullOrUndefined = false;
+          rows = csv.generate(testObjectArrayData).split("\r\n");
+        });
+
+        afterEach(function() {
+          csv.ignoreNullOrUndefined = true;
+        });
+
+        it('should include values that exist', function() {
+          rows[0].split(",")[0].should.equal('"a"');
+          rows[1].split(",")[0].should.equal('"b"');
+        });
+
+        it('should include null', function() {
+          rows[0].split(",")[1].should.equal('"null"');
+          rows[1].split(",")[1].should.equal('"null"');
+        });
+
+        it('should include undefined', function() {
+          rows[0].split(",")[2].should.equal('"undefined"');
+          rows[1].split(",")[2].should.equal('"undefined"');
+        });
+      });
+    });
+  });
+
+  it('should return csv', function() {
+    csv.generate(test1Data).should.equal('"a","b","c"\r\n"d","e","f"\r\n');
+  });
+
+  it('should generate a csv that ignores null', function() {
+    csv.generate(test2Data).should.equal('"a","b",\r\n');
+  });
+
+  it('should generate a csv that ignores undefined', function() {
+    csv.generate(test3Data).should.equal('"a","b",\r\n');
+  });
+
+  it('should generate a csv that include null', function() {
+    var prevOption = csv.ignoreNullOrUndefined;
+    csv.ignoreNullOrUndefined = false;    
+    csv.generate(test2Data).should.equal('"a","b","null"\r\n');
+    csv.ignoreNullOrUndefined = prevOption;
+  });
+
+  it('should generate a csv that includes undefined', function() {
+    var prevOption = csv.ignoreNullOrUndefined;
+    csv.ignoreNullOrUndefined = false;
+
+    csv.generate(test3Data).should.equal('"a","b","undefined"\r\n');
+    csv.ignoreNullOrUndefined = prevOption;
+  });
+
+  it('should generate a tsv', function() {
+    var prevSeparator = csv.separator;
+    csv.separator = '\t';
+    csv.generate(test1Data).should.equal('"a"\t"b"\t"c"\r\n"d"\t"e"\t"f"\r\n');
+    csv.separator = prevSeparator;
+  });
+
+  it('should generate a quoted csv', function() {
+    var prevSetting = csv.preventCast;
+    csv.preventCast = true;
+    csv.generate(test1Data).should.equal('="a",="b",="c"\r\n="d",="e",="f"\r\n');
+    csv.preventCast = prevSetting;
+  });
+});
+
+
 describe('res.csv()', function() {
 
   describe('when given an array of objects', function() {