If you're looking to delve into AngularJS, it's crucial to start by understanding its Dependency Injection mechanism and how scopes and data binding operate. It seems like your issues go beyond just incorrect posting methods.
Regarding your specific query, when using the $http method, make sure to provide the data in the format of a JavaScript object as shown below:
$http({
method: 'POST',
url: 'http://localhost:8080/api/labels/',
data: {
key: 'key',
subkey: 'subkey',
et: 'et',
ru: 'ru',
en: 'en',
desc: 'desc'
}
}).then(function successCallback(response) {
console.log(response);
getData(response);
// console.log(response.data[0].key);
// console.log(response.data[0].tkTextValues[0].text);
// console.log(response.data.length)
}, function errorCallback(response) {
console.log('error');
});