To POST form data with the RestTemplate class in Spring, you can use the postForObject method and pass it a URL, an object containing the form data, and the response type.
To respond with an HTTP 400 error in a Spring MVC controller method that returns a String, you can throw a ResponseStatusException with a status of BAD_REQUEST.
The "failed to lazily initialize a collection of role" exception in Hibernate is thrown when you try to access an uninitialized collection from a Hibernate entity when the entity is in a detached state.
If IntelliJ is saying "No beans of type 'X' found for autowiring" for a repository that you are trying to autowire, it means that the Spring application context does not contain a bean of the specified type.
If you want to use the @JsonIgnore annotation to ignore a field during serialization but not during deserialization, you can use the @JsonIgnoreProperties annotation and set its writeOnly property to true.
To make a POST request with the RestTemplate in JSON, you can use the postForObject() method and pass it the URL of the request, the request body, the response type, and the HttpEntity object that represents the request headers and body.
To redirect to an external URL from a controller action in Spring MVC, you can use the RedirectView class and return it from the controller action.
To set the active profile and the configuration location from the command line in Spring Boot, you can use the spring.profiles.active and spring.config.name properties.
The error "Error creating bean with name 'dataSource' defined in class path resource" in Spring Boot typically indicates that there is a problem with the configuration of the dataSource bean.
In a Spring Boot application, you can log all requests and responses, along with exceptions, in a single place by using a combination of Spring Boot's logging framework and request/response interceptors.