---
title: "Validate templates"
description: "Check a template against the shape of its model without rendering it, when it is saved and in a test over every template."
audience: "Developers"
kind: "How-to guide"
status: "Current"
version: "main · 3.3 (unreleased)"
slug: "validate-templates"
url: "https://docs.allors.com/documents/validate-templates/"
---

# Validate templates

> **Status: Current.** How-to guide for developers.

This guide shows how to check a template against the shape of its model before any data exists. Run the check where templates enter the application, when one is saved or uploaded, and in a test over every template the application ships, so that a typo is a failed check rather than a blank in a document.

`Validate` checks a template against the shape of its model, without rendering and without data: every path, attribute, block and document setting. It never throws for what the template says; it throws only when the bytes are not an OpenDocument text.

```csharp
using Allors.Document.Reflection;


IShape model = ReflectionShape.Arguments<InvoiceModel>();
TemplateValidation validation = OpenDocumentTemplate.Validate(templateBytes, model);


if (!validation.IsValid)
{
    foreach (Finding finding in validation.Errors)
    {
        Console.WriteLine(finding); // error: <$Invoice.Totl>: Invoice has no member Totl (content.xml paragraph 12 "Total <$Invoice.Totl>")
    }
}
```

The shape is the root the template renders against. `ReflectionShape.Arguments<T>()` is what `OpenDocumentTemplate<T>` sees: the public properties of `T` by their exact names. `ReflectionShape.Of<T>()` is an object of `T` itself, for a model rendered through `ReflectionResolver`. For a dictionary model use `DictionaryShape`: `DictionaryShape.Open` accepts every member, `new DictionaryShape(members)` knows exactly which names exist and what their shapes are. `IsValid` is true when there are no errors. Inside an `<@if>` or `<@ifdef>` block the guarded path is narrowed to the shapes that have the member, for models whose shapes declare `Variants`; the else of an `<@ifdef>` sees the shapes without it, the else of an `<@if>` sees them all, `not` swaps the two, and an else with a test of its own narrows again.