英文:
HttpMessageNotWritableException: Could not write JSON: EL1025E: The collection has '0' elements, index '0' is invalid
问题
Json请求发送到后端时抛出异常。我的错误在哪里？
无法编写JSON：EL1025E：集合有'0'个元素，索引'0'无效；嵌套异常是com.fasterxml.jackson.databind.JsonMappingException：EL1025E：集合有'0'个元素，索引'0'无效（通过引用链：org.springframework.data.domain.PageImpl["content"]->java.util.Collections$UnmodifiableRandomAccessList[3]->com.sun.proxy.$Proxy277["teacherName"]）
服务器遇到了意外情况，阻止了它无法完成请求。
Java代码
public Page<CourseProjection> fetchAllPublishCourses(Integer page, Integer size, String search,
String sortBy) {
// ...（代码中的其他部分）
}
JavaScript代码
var obj2 = JSON.stringify(obj);
$.ajax({
url: apiBasePath + '/courses?page=' + page_num + '&size=12&sort='
+ sortCourses + '&search='
+ encodeURIComponent(JSON.stringify(obj)),
type: "GET",
dataType: "json",
contentType: "application/json; charset=utf-8",
success: function (response) {
// ...（代码中的其他部分）
},
error: function (response) {
// ...（代码中的其他部分）
}
});
英文:
Json request being sent to backend throws the exception. Where is my mistake?
> Could not write JSON: EL1025E: The collection has '0' elements, index '0' is invalid; nested exception is com.fasterxml.jackson.databind.JsonMappingException: EL1025E: The collection has '0' elements, index '0' is invalid (through reference chain: org.springframework.data.domain.PageImpl["content"]->java.util.Collections$UnmodifiableRandomAccessList[3]->com.sun.proxy.$Proxy277["teacherName"])
> The server encountered an unexpected condition that prevented it from fulfilling the request.
Java code
public Page<CourseProjection> fetchAllPublishCourses(Integer page, Integer size, String search,
String sortBy) {
Page<CourseProjection> response = null;
JsonParser jsonParser = new JsonParser();
Specification<Course> spec = null;
LinkedList<Filter> subjectFilters = new LinkedList<>();
LinkedList<Filter> subCategoryFilters = new LinkedList<>();
LinkedList<Filter> examSegmentFilters = new LinkedList<>();
LinkedList<Filter> categoryFilters = new LinkedList<>();
LinkedList<Filter> otherFilters = new LinkedList<>();
try {
Pageable pageable = null;
Sort sort = null;
if (search != null && !search.isEmpty()) {
JsonObject jsonObject = (JsonObject) jsonParser.parse(search);
if (jsonObject != null) {
JsonArray jsonArray = (JsonArray) jsonObject.get("filters");
for (int i = 0; i < jsonArray.size(); i++) {
Filter filter = new Filter();
filter.setFilterName(
((JsonObject) jsonArray.get(i)).get("filterName").toString().replaceAll("\"", ""));
filter.setValue(
((JsonObject) jsonArray.get(i)).get("value").toString().replaceAll("\"", ""));
if (filter.getFilterName().equalsIgnoreCase("courseSubject")) {
subjectFilters.add(filter);
} else if (filter.getFilterName().equalsIgnoreCase("courseSubCategory")) {
subCategoryFilters.add(filter);
} else if (filter.getFilterName().equalsIgnoreCase("courseExamSegment")) {
examSegmentFilters.add(filter);
} else if (filter.getFilterName().equalsIgnoreCase("courseCategory")) {
if (filter.getValue().equalsIgnoreCase("current affairs")) {
Filter currentAffairsFilter = new Filter();
currentAffairsFilter.setFilterName("courseSubject");
currentAffairsFilter.setValue("Current Affairs");
subjectFilters.add(currentAffairsFilter);
} else {
categoryFilters.add(filter);
}
} else {
otherFilters.add(filter);
}
}
otherFilters.add(Filter.addDeafultFilter());
}
if (otherFilters != null && otherFilters.size() > 0) {
CourseSpecificationBuilder builder = new CourseSpecificationBuilder();
spec = builder.build(otherFilters, subjectFilters, subCategoryFilters, examSegmentFilters,
categoryFilters);
}
}
if (sortBy != null && !sortBy.isEmpty()) {
switch (sortBy) {
case "atoz":
sort = new Sort(Direction.ASC, new String[]{"courseTitle"});
break;
case "ztoa":
sort = new Sort(Direction.DESC, new String[]{"courseTitle"});
break;
case "popular":
sort = new Sort(Direction.ASC, "position");
break;
}
}
if (spec != null) {
if (page != null && size != null) {
if (sort != null) {
pageable = PageRequest.of(page, size, sort);
response = courseRepository.findAll(spec, CourseProjection.class, pageable);
} else {
pageable = PageRequest.of(page, size);
response = courseRepository.findAll(spec, CourseProjection.class, pageable);
}
} else {
pageable = PageRequest.of((page != null ? page : 0), (size != null ? size : 0));
response = courseRepository.findAll(spec, CourseProjection.class, pageable);
}
}
} catch (Exception e) {
LOGGER.error(Course.class.getName() + " Exception Occurred");
emailService.sendErrorLogsToDevelopers(ExceptionUtils.getStackTrace(e));
}
return response;
}
JavaScript
var obj2 = JSON.stringify(obj);
$.ajax({
url: apiBasePath + '/courses?page=' + page_num + '&size=12&sort='
+ sortCourses + '&search='
+ encodeURIComponent(JSON.stringify(obj)),
type: "GET",
dataType: "json",
contentType: "application/json; charset=utf-8",
success: function (response) {
console.log("Success : " + response);
$('.load-courses-progress-bar').hide();
$('.course-listing').css("visibility", "visible");
$('.mat-content').css("overflow-y", "auto")
if ($(window).width() > '767') {
$('body,html').animate({
scrollTop: $(".course-listing").offset().top - 100
}, 1000);
setTimeout(function () {
$('.mat-all-curses-main-tab').hide();
}, 2000);
} else {
$(".mat-all-curses-main-tab-mobile").hide("0", function () {
$('body,html').animate({
scrollTop: $(".course-listing").offset().top - 200
}, 1000);
})
}
showCourses(response);
showTrendingCourse(response, obj);
},
error: function (response) {
console.log("Error : " + JSON.stringify(response));
}
});
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