jqGrid: Disable form fields when editing

You can implement your requirements in different ways. For example, inside of beforeShowForm event you can hide or show the

jQuery("#list").jqGrid({
    colModel: [
        { name: 'Name', width: 200, editable: true },
   //...

}).jqGrid('navGrid','#pager', { edit: true, add: true, del: false},
          { // edit option
              beforeShowForm: function(form) { $('#tr_Name', form).hide(); }
          },
          { // add option
              beforeShowForm: function(form) { $('#tr_Name', form).show(); }
          });

where the id "tr_Name" is constructed from "tr_" prefix and "Name" - the name property of the column from the colModel.

UPDATED: In the answer and in another one are shown one more way how the properties can be changed dynamically immediately before the editing will be initialized.

UPDATED 2: Free jqGrid allows to define editable as callback function or as "disabled", "hidden" or "readonly". See the wiki article. It allows to implement the same requirements more easy.

To make the field editable or not, this is what I wound up coding after searching for an answer for a while (to disable editing on in-row edit, but allow it on 'Add') and not finding the answer I needed:

colModel :[ 
    {name:'id', index:'id', editable:false, ...

    }).navGrid("#pager",{edit:false,add:true,del:false,search:false,refresh:true},
        {}, // edit
        {   
            beforeInitData: function(formid) {
                $("#list").jqGrid('setColProp','id',{editable:true});
            },
            afterShowForm: function (formid) {
                $("#list").jqGrid('setColProp','id',{editable:false});
            },