AppML – Defining and Using Models: Structure Your Data the Right Way

Introduction – Why AppML Models Matter

In AppML, models are the blueprint that define how data should behave in your application. Unlike raw JSON or XML files, a model adds structure, validation rules, and dynamic control to your AppML-based apps.

In this article, you’ll learn:

• What AppML models are and why you should use them
• How to define models using .json or .xml
• How models work with controllers and views
• Real examples for input validation, schema constraints, and CRUD operations

What Is an AppML Model?

An AppML model is a structured definition (usually a .json file) that describes the fields, data types, rules, and validation for a dataset.

It helps AppML understand how to:

• Render input forms
• Perform client-side and server-side validation
• Filter, sort, and manage data
• Connect views and controllers to the correct schema

Sample AppML Model Structure (JSON)

models/product-model.json

{
  "tablename": "products",
  "orderby": "name",
  "fields": [
    { "name": "id", "primarykey": true },
    { "name": "name", "required": true },
    { "name": "price", "datatype": "number", "required": true },
    { "name": "category" }
  ]
}

Breakdown:

Example – Using a Model in HTML View

<div appml-model="models/product-model.json" appml-data="get-products.php">
  <input name="name">
  <input name="price" type="number">
  <input name="category">
  <button appml-submit>Save</button>
</div>

The model guides how fields are displayed and validated before submission.

Advanced Use – With Controller Logic

Combine models with a controller for intelligent behavior:

myAppML.onvalidate = function() {
  if (myAppML.data.price < 1) {
    alert("Price must be at least $1");
    return false;
  }
  return true;
};

This enforces dynamic validation beyond the static rules in the model.

Using AppML Models with Databases

The tablename field in the model links it to a backend SQL table (via PHP or ASP).

Backend: get-products.php

$mysqli = new mysqli("localhost", "root", "", "shop");
$sql = "SELECT * FROM products ORDER BY name";
$result = $mysqli->query($sql);

$data = [];
while ($row = $result->fetch_assoc()) {
  $data[] = $row;
}
echo json_encode($data);

With appml-model="product-model.json", AppML will auto-match the data fields to the model schema.

XML-Based Model Alternative

Although JSON is preferred, AppML supports XML too:

product-model.xml

<model>
  <tablename>products</tablename>
  <orderby>name</orderby>
  <fields>
    <field name="id" primarykey="true" />
    <field name="name" required="true" />
    <field name="price" datatype="number" required="true" />
    <field name="category" />
  </fields>
</model>

Use it like:

<div appml-model="models/product-model.xml" appml-data="get-products.php">
  ...
</div>

Summary – Recap & Key Takeaways

Models define the structure and rules of your application’s data in AppML. By declaring fields, data types, and validation logic, they give your apps clarity and reusability.

Key Takeaways:

• AppML models define the data schema (field names, types, requirements)
• Used via appml-model="..." attribute
• Supports JSON (preferred) and XML
• Integrates with controllers for advanced behavior
• Great for forms, input validation, and CRUD

Models separate logic from presentation, making your apps scalable and easier to maintain.

FAQs – AppML Models

Is the model file required in every AppML app?
No, but it is highly recommended for structured data and form input scenarios.

Can I use both appml-model and appml-controller together?
Yes, and this is a best practice for apps that need logic + schema validation.

What happens if I leave out datatype in a field?
It defaults to “string”. You can leave it out for simple text fields.

Can I update the model at runtime?
Not directly. You’ll need to reload or swap the appml-model source file.

Can I use models with both static JSON and server-side PHP?
Absolutely. The model defines structure; data can come from any source.