The fnTest method of the filter gets the value to test as the only parameter and returns, whether the row with the given value should be filtered or not.

var oFilter = new sap.ui.model.Filter("property", function(value) {
    return (value > 100); 
});

The fnCompare method of the Sorter gets the two values to compare as parameters and returns -1, 0 or 1, dependent on which of the two values should be ordered before the other:

var oSorter = new sap.ui.model.Sorter("property");
oSorter.fnCompare = function(value1, value2) {
    if (value1 < value2) return -1;
    if (value1 == value2) return 0;
    if (value1 > value2) return 1;
};

The following example shows a simple JSON model with the different binding paths:

{
    company: {
        name: "Treefish Inc",
        info: {
            employees: 3,
        },
        contacts: [
            {
                name: "Barbara",
                phone: "873"
            },
            {
                name: "Gerry",
                phone: "734"
            },
            {
                name: "Susan",
                phone: "275"
            }
        ]
    }
}

Absolute binding paths within this model:

/company/name
/company/info/employees
/company/contacts

Relative binding paths within the "/company" context:

name
info/employees
contacts

Relative binding paths within a list binding of "/company/contacts":

name
phone

The TypedJSONModel and TypedJSONContext classes provide strongly-typed wrappers around the existing JSONModel and Context classes. The TypedJSONModel#setData and TypedJSONModel#getData methods accept and return strongly typed data according to the underlying data structure. Manipulating and accessing data in the model via TypedJSONModel#setProperty and TypedJSONModel#getProperty is type-safe, ensuring that the data structure remains consistent and only valid binding paths are passed to these methods.

These features not only prevent runtime errors but allow for a richer development experience due to autocompletion features.

The following code snippet illustrates how to use the TypedJSONModel and TypedJSONContext classes:

import { TypedJSONModel } from 'sap/ui/model/json/TypedJSONModel';

interface Order {
  order_id: string;
  items: OrderItem[];
}
interface OrderItem {
  item_id: string;
  approved: boolean;
}

const data: { order: Order } = {
  order: { order_id: "PO-2025-0042", items: [...] },
};

// Benefit from TypeScript's type inference:
const model = new TypedJSONModel(data);
const firstOrderItem = model.getProperty("/order/items/0"); // firstOrderItem: OrderItem -> automatically typed
const approved = firstOrderItem.approved; // approved: boolean -> automatically typed

// Prevent runtime errors at compile time:
model.setProperty("/order/items/0/approved", "true");
// this will raise a typescript error because "true" is not a boolean

const itemID = model.getProperty("/order/items/0/itemID");
// this will raise a typescript error because itemID does not exist on OrderItem

You can even use a TypedJSONContext to access properties with relative binding paths in a type-safe manner:

// ...typing as in the previous example...
const context = model.createBindingContext("/order/items/0"); // returns a TypedJSONContext
const itemId = context.getProperty("item_id"); // itemId: string -> automatically typed

// you can also set properties using a context and a relative path:
model.setProperty("approved", false, context); // only accepts "approved" or "item_id" as relative paths -> ensured by TypeScript

The TypedJSONModel and TypedJSONContext classes currently provide a typed wrapper for the following methods:

import Controller from "sap/ui/core/mvc/Controller";
import { TypedJSONModel } from 'sap/ui/model/json/TypedJSONModel';

export default class App extends Controller {
  model: TypedJSONModel<{ order: Order }>;
  ...
}