QML form layout

I use QML for UI in my app and now I want to build some form.This is a code:

Window {    width: 400    height: 600    flags: Qt.Dialog    modality: Qt.ApplicationModal    GridLayout {        id: mainLayout        columns: 2        rowSpacing: 5        columnSpacing: 5        anchors {            top: parent.top;            left: parent.left            right: parent.right        }        Label { text: "field1" }        TextField { id: field1; }        Label { text: "field2"}        TextField { id: field2 }    }}

How can I set width for the TextFields? Most of them have to fit all the space in the right column.

That how it looks now:

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