java - Why can't the browser get the found data? The background outputs normally and no error is reported.

Question

Answer 1

If you try-catch in the method, the query should report an error

Answer 2

The background outputs normally. What is outputted? If the software does not report an error, it does not mean that there is no error. Use SYSTEM.OUT.PRINGTLN to print the results you want to output and see if the result calculation is correct

Answer 3

Look at the results of your query and what kind of results you return to the front page. According to what you said, the system outputs normally. It should be that the front page is not parsing the background data normally

Answer 4

Status code 500 is obviously an error reported in the background.

Answer 5

500 is probably a problem with the background. The background should not output normally

Answer 6

Status 500, an error was reported in the background. Is the exception information swallowed? Use try/catch to print out the exception information

Answer 7

compile group: 'com.fasterxml.jackson.core', name: 'jackson-annotations', version: '2.8.7'
compile group: 'com.fasterxml.jackson.core', name: 'jackson-databind' , version: '2.8.7'
compile group: 'com.fasterxml.jackson.core', name: 'jackson-core', version: '2.8.7'
See if your project references these three packages. Sometimes, although no error is reported in your background, spring will report this json conversion exception because these packages are missing

Answer 8

It’s difficult to judge your error just by looking at how you write your entity class and how you write your page

Answer 9

Did you not specify the request method

@RequestMapping(value = "", method = RequestMethod.POST)