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From: Apache Wiki <wikidiffs@apache.org>
To: Apache Wiki <wikidiffs@apache.org>
Date: Wed, 01 Dec 2010 18:49:58 -0000
Message-ID: <20101201184958.93912.66202@eosnew.apache.org>
Subject: 
 =?utf-8?q?=5BCouchdb_Wiki=5D_Update_of_=22JavascriptPatternViewCommonJs?=
 =?utf-8?q?=22_by_jpfiset?=

Dear Wiki user,

You have subscribed to a wiki page or wiki category on "Couchdb Wiki" for c=
hange notification.

The "JavascriptPatternViewCommonJs" page has been changed by jpfiset.
http://wiki.apache.org/couchdb/JavascriptPatternViewCommonJs

--------------------------------------------------

New page:
=3D Javascript Pattern to Share Code Between View and Other Functions =3D

This works only if one is using CouchApp since this pattern is dependent on=
 CouchApp directives.

CouchApp directives are explained here: [[http://japhr.blogspot.com/2010/02=
/couchapp-templates-for-showing.html|Chris Strom's blog]].

=3D=3D Shared Code =3D=3D

The following Javascript code fragment can be used as an example of a share=
d library between a View Map function and other functions (in this example,=
 a validate_update_doc function). In the design document, create an entry u=
nder vendor.myComp.utils which is:

{{{#!highlight javascript
var utils =3D {

   isArray: function(o) {
      if( typeof(o) !=3D=3D 'object' ) return false;
      if( typeof(o.length) !=3D=3D 'number' ) return false;
      if( typeof(o.push) !=3D=3D 'function' ) return false;
      if( typeof(o.pop) !=3D=3D 'function' ) return false;
      if( typeof(o.concat) !=3D=3D 'function' ) return false;
      if( typeof(o.join) !=3D=3D 'function' ) return false;
      if( typeof(o.slice) !=3D=3D 'function' ) return false;
      if( typeof(o.reverse) !=3D=3D 'function' ) return false;
      if( typeof(o.splice) !=3D=3D 'function' ) return false;
      if( typeof(o.sort) !=3D=3D 'function' ) return false;

      return true;
   }
};

// CommonJS bindings
if( typeof(exports) =3D=3D=3D 'object' ) {
   exports.isArray =3D n2utils.isArray;
};
}}}

Notes:
  1. In a couchApp (an application developed and deployed using CouchApp), =
the content above would be saved in a file named "vendor/myComp/utils.js". =

  1. Files uploaded using CouchApp are stripped of their extensions since i=
t would lead to confusion as the dot (period) is the natural Javascript sep=
arator. Therefore, the shared code is "known" by CouchApp as "vendor/myComp=
/utils.js"  while is is referred internally to the design documents as "ven=
dor.myComp.utils".

=3D=3D Inclusion using CommonJs =3D=3D

Using CommonJs, the library defined above (shared code) would be included i=
n a "validate_update_doc" function as follows:

{{{#!highlight javascript
function(newDoc, oldDoc, userCtxt) {
	=

   var myUtils =3D require('vendor/myComp/utils');
   =

   // Verify geometries
   if( newDoc.type =3D=3D=3D 'myDoc' ) {

      // Verify that list is an array
      if( !myUtils.isArray(newDoc.list) ) {
         throw( {forbidden: 'Invalid or missing list'} );
      }
   }
}
}}}

Notes:
  1. The 'require' function in CommonJs exposes the 'exports' defined in th=
e library and assigns them to the variable.
  1. The variable 'utils' can be used to access the definitions from the sh=
ared code.
  1. Note that the path uses slashes and that the file extension (if using =
CouchApp) is omitted. =


=3D=3D Inclusion using CouchApp directives =3D=3D

Since View Map and View Reduce functions do not have access to CommonJs, th=
e way one can include shared code within those functions is to use CouchApp=
 directives. More specifically, in CouchApp, the 'code' directive instructs=
 the tool to include the content of another file (verbatim) at the location=
 of the directive before uploading the file to CouchDb.

An example of View Map function that shares the code defined above:

{{{#!highlight javascript
function(doc) {
	=

   // !code vendor/myComp/utils.js
   =

   // Verify that list is an array
   if( utils.isArray(doc.list) ) {
      for(var i=3D0,e=3Ddoc.list.length; i<e; ++i) {
         emit(doc.list[i],doc);
      }
   }
}
}}}

Since CouchApp includes the whole file at the point of the directive, the r=
esulting content uploaded for this map function is:


{{{#!highlight javascript
function(doc) {
	=

   var utils =3D {
   =

      isArray: function(o) {
         if( typeof(o) !=3D=3D 'object' ) return false;
         if( typeof(o.length) !=3D=3D 'number' ) return false;
         if( typeof(o.push) !=3D=3D 'function' ) return false;
         if( typeof(o.pop) !=3D=3D 'function' ) return false;
         if( typeof(o.concat) !=3D=3D 'function' ) return false;
         if( typeof(o.join) !=3D=3D 'function' ) return false;
         if( typeof(o.slice) !=3D=3D 'function' ) return false;
         if( typeof(o.reverse) !=3D=3D 'function' ) return false;
         if( typeof(o.splice) !=3D=3D 'function' ) return false;
         if( typeof(o.sort) !=3D=3D 'function' ) return false;

         return true;
      }
   };

   // CommonJS bindings
   if( typeof(exports) =3D=3D=3D 'object' ) {
      exports.isArray =3D n2utils.isArray;
   };
   =

   // Verify that list is an array
   if( utils.isArray(doc.list) ) {
      for(var i=3D0,e=3Ddoc.list.length; i<e; ++i) {
         emit(doc.list[i],doc);
      }
   }
}
}}}

Notes:
  1. In this case, the CommonJs bindings are ignored since 'exports' is not=
 defined in a View Map function.
  1. The shared code is accessed via the variable named 'utils' defined in =
the external content file.
  1. The CouchApp directive requires the file extension.