This is the file.

Third time trying to upload the file...

Come on! I can't upload the zip file because the form of the forum crash... 
Sorry but I'm desperate now so I'm going to paste the code here...

// THIS IS THE JSONSTRING RETURNED BY THE DATA SOURCE TRANSPORT
[
{
"_sattoci_id":1,
"_sattoci_max":0
},{
"_sattoci_id":2, // This is what I'm getting
"_sattoci_max":0.16 // This is the value I expect when I finalize editing mode
}
]

// CUSTOM EDITOR
function ivaEditor(container, options) {
$('<input name="' + options.field + '" />')
.appendTo(container)
.kendoDropDownList({
// When avalue primitive is false there's no difference
// valuePrimitive: false,
valuePrimitive: true,
optionLabel: "SIN IVA",
autoBind: true,
dataValueField: "_sattoci_id",
dataTextField: "_sattoci_max",
dataSource: {
transport: {
read: "/api/SatCatTasasImpuestos/ivaT",
dataType: "json",
}
}
});
}

var conceptosGridData = new kendo.data.DataSource({
schema: {
model: {
id: "cve_producto",
fields: {
cta_predial: {type:"string", nullable:true},
no_pedimento: {type:"string", nullable:true},
// I've remove nullable from column definition because some people suggest to do so
// iva: {type:"string", nullable:true},
iva: {type:"string"},
}
}
}
});

var conceptosGrid = $("#grid-conceptos").kendoGrid({
dataSource: conceptosGridData,
save: onSave,
height: 350,
scrollable: true,
resizable: true,
columns:[{
width: 150,
editor: ivaEditor,
field: "iva",
title: "IVA"
// This alternative shows undefined
// template: "#=iva._sattoci_max#",
// This alternative shows the value instead of the text
// template: "#=iva#",
}],
editable: "inline"
}).data("kendoGrid");

Hello,

Thank you for the provided information.

I made an example based on the provided code and it is working as expected on my end.

Please check it and advise if it defers from the real application scenario:

http://dojo.telerik.com/AFeDiy

If additional assistance is needed, the example can be used for reference to demonstrate the issue.

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

As for the zip upload, I apologize for the inconvenience caused by the server upload.

Regards,
Stefan
Progress Telerik

For MVC you need to use the method like. You will need to specify the ViewData in the code behind

columns.ForeignKey(e => e.TotalRewardFieldType, (System.Collections.IEnumerable)ViewData["FieldTypes"], "Value", "Text").EditorTemplateName("FieldType");