<property key="datasource" type="datasource" isList="true" required="false">
<caption>Data Source</caption>
<description/>
</property>
If you using this xml code for get list. Then you can use below code to update/change mendix object attribute values.
useEffect(() => {
try {
// Get List of Mendix Objects
const {items } = props.datasource;
let listOfMxObjects = items.map(item => item[Object.getOwnPropertySymbols(item)[0]]);
// Update List of Mendix Objects
for (let i = 0; i < listOfObjects.length; i++) {
listOfMxObjects[i].set('ImageWidth',100)
listOfMxObjects[i].set('ImageHeight',200)
}
} catch (e) {
console.log("error", e);
}
}, [props])
Hope this will help you.
Thanks