How-to articles, tricks, and solutions about SPRING

The 'Field required a bean of type that could not be found' error in a Spring application typically indicates that the application is trying to inject a dependency into a field, but it cannot find a bean of the required type in the application context.

No qualifying bean of type found for dependency is an error message that can occur when you are using the @Autowired annotation in Spring to inject a bean dependency.

In Spring MVC, the @RequestParam annotation is used to bind a request parameter to a method parameter.

To add a context path to a Spring Boot application, you can use the server.context-path property in the application's application.properties file.

This error is usually encountered when trying to parse a JSON string that does not start with a JSON array, but rather a JSON object.

To download a file from a Spring controller, you can use the ResponseEntity class along with the InputStreamResource class.

To get a list of JSON objects using the Spring RestTemplate, you can use the exchange() method to send an HTTP GET request to the server, and then use the getBody() method of the ResponseEntity object to retrieve the list of objects.

To log SQL statements in Spring Boot, you can configure the logging level of the org.hibernate.SQL logger to DEBUG or TRACE.

To check a string in the response body with MockMvc, you can use the andExpect() method of the MockMvcResultMatchers class.

To configure the port for a Spring Boot application, you can use the server.port property in the application's configuration file. The configuration file can be a application.properties file in the classpath, or a application.yml file in the classpath.

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.

To use multiple external configuration files with Spring Boot, you can use the spring.config.name property to specify the names of the configuration files.

To create a cron expression that triggers an event every day at 1:01 AM, you can use the following cron expression:

To return a simple string as JSON in a Spring MVC Rest Controller, you can use the @ResponseBody annotation and return the string directly.

To perform a GET request with parameters using the RestTemplate in Spring, you can use the getForObject() method and pass it a URL with placeholders for the parameters, as well as a map of the parameter values.

The @Autowired annotation in Spring is used to inject dependencies into a Java object.