title: ko.mapping shows function in input fields insted of value
body: <p>I'm having an issue with ko.mapping plugin for knockout.
  I've been thoroughly searching for an answer but couldn't find anything.</p>
  
  <p>I'm using knockout in conjunction with boilerplate js, but I think that's not the problem. </p>
  
  <p><strong>Here's the JS:</strong></p>
  
  <pre><code>define(function(require){
  var Boiler = require('Boiler'),
      komapping = require('knockout_mapping');
  
  ko.mapping = komapping;
  
  var mapping = {
                  'observe': ['disciplina',
                              'numero',
                              'paraUsoEn',
                              'detalleCertificadoCalidad',
                              'comentariosGenerales']
                };
  
  var RequisicionViewModel = function(moduleContext, params, bindingCallback){
      /* Propiedades del modelo */
      var self = this;
      this.disciplinas = ko.observableArray();
      this.requisicion = ko.mapping.fromJS({});
  
      /* Obtener los valores del WS */
  
      // Obtener las disciplinas
      moduleContext.requestor.get('/disciplina/').done(function(data){
          self.disciplinas(data);
      });
  
      // Obtener la plantilla de la requisición
      moduleContext.requestor.get('/requisicion/ZFN-5612').done(function(data){
  
          ko.mapping.fromJS(data, mapping, self.requisicion);
  
          self.requisicion.planos = ko.observable("Jola!")
  
          // Aplicar el binding
          bindingCallback();
      });
  
      /* Gestión de eventos */
      this.onGuardarClicked = function(){
  
          console.log(ko.mapping.toJSON(self.requisicion));
  
      };
  };
  
  return RequisicionViewModel;
  });
  </code></pre>
  
  <p>As you can see I define only the objects I want to be observable.</p>
  
  <p><strong>Here's the HTML</strong></p>
  
  <pre><code>&lt;div id="uso-planos-informacion" class="clearfix" data-bind="with:requisicion"&gt;
      &lt;div class="control-grp"&gt;
          &lt;label for="usarse-en" class="text-solid"&gt;{{nls.label_usarse_en}}&lt;/label&gt;
          &lt;input id="usarse-en" 
                 type="text"
                 data-bind="value:paraUsoEn"&gt;
      &lt;/div&gt;
  
      &lt;div class="control-grp"&gt;
          &lt;label for="planos" class="text-solid"&gt;{{nls.label_planos}}&lt;/label&gt;
          &lt;input id="planos" 
                 type="text"&gt;
      &lt;/div&gt;
  
      &lt;div class="control-grp"&gt;
          &lt;label for="certificado-calidad" class="text-solid"&gt;{{nls.certificado_calidad}}&lt;/label&gt;
          &lt;input id="certificado-calidad" 
                 type="text"
                 data-bind="value:detalleCertificadoCalidad"&gt;
      &lt;/div&gt;
  &lt;/div&gt;&lt;!--  Termina uso-planos-informacion --&gt;
  </code></pre>
  
  <p>It's much longer, but for brevity I'll just paste 2 fields that show the error.
  Finally when I run it, this is what happens:</p>
  
  <p><a href="http://i.stack.imgur.com/2Vasm.png" rel="nofollow">http://i.stack.imgur.com/2Vasm.png</a></p>
  
  <p><strong>Here's what I've tried so far:</strong></p>
  
  <ul>
  <li>Use () after the variable name so that it evaluates and shows the value inside the observable.</li>
  </ul>
  
  <p>This works, but the observable looses it's properties or something like that because it does not get updated again after this.</p>
  
  <ul>
  <li><p>Defining a create function for the mapping.
  Al ready tried this:</p>
  
  <p>var mapping = {'paraUsoEn':{create:function(options){return ko.observable(options.data);}}}</p></li>
  </ul>
  
  <p>And does not work. The value does not appear, neither it can be updated.</p>
  
  <p>Hope Someone has solved this kind of problem, otherwise I'll have to do the mapping manually (which works!).</p>
  
  <p>Thanks!</p>