1. 概述
本篇 Reddit App 案例研究將跟蹤帖子提交嘗試的歷史記錄，並使狀態更具描述性，更易於理解。
2. 改進 Post 實體
首先，讓我們通過將舊的 String 狀態字段在 Post 實體中替換為更完整的一系列提交響應，並跟蹤更多信息來開始。
public class Post {
...
@OneToMany(fetch = FetchType.EAGER, mappedBy = "post")
private List<SubmissionResponse> submissionsResponse;
}接下來，讓我們看看在新的提交響應實體中我們實際跟蹤的內容：
@Entity
public class SubmissionResponse implements IEntity {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
private int attemptNumber;
private String content;
private Date submissionDate;
private Date scoreCheckDate;
@JsonIgnore
@ManyToOne
@JoinColumn(name = "post_id", nullable = false)
private Post post;
public SubmissionResponse(int attemptNumber, String content, Post post) {
super();
this.attemptNumber = attemptNumber;
this.content = content;
this.submissionDate = new Date();
this.post = post;
}
@Override
public String toString() {
StringBuilder builder = new StringBuilder();
builder.append("Attempt No ").append(attemptNumber).append(" : ").append(content);
return builder.toString();
}
}請注意，每次已消耗的提交嘗試都對應一個SubmissionResponse，以便：
- attemptNumber：本次嘗試的編號
- content：本次嘗試的詳細響應
- submissionDate：本次嘗試的提交日期
- scoreCheckDate：我們在本次嘗試中檢查 Reddit Post 的日期
以下是一個簡單的 Spring Data JPA 倉庫示例：
public interface SubmissionResponseRepository extends JpaRepository<SubmissionResponse, Long> {
SubmissionResponse findOneByPostAndAttemptNumber(Post post, int attemptNumber);
}3. 調度服務
現在我們需要開始修改服務層以跟蹤這些額外信息。
我們首先要確保我們有格式良好、成功或失敗的原因，以便將 Post 標記為成功或失敗：
private final static String SCORE_TEMPLATE = "score %d %s minimum score %d";
private final static String TOTAL_VOTES_TEMPLATE = "total votes %d %s minimum total votes %d";
protected String getFailReason(Post post, PostScores postScores) {
StringBuilder builder = new StringBuilder();
builder.append("Failed because ");
builder.append(String.format(
SCORE_TEMPLATE, postScores.getScore(), "<", post.getMinScoreRequired()));
if (post.getMinTotalVotes() > 0) {
builder.append(" and ");
builder.append(String.format(TOTAL_VOTES_TEMPLATE,
postScores.getTotalVotes(), "<", post.getMinTotalVotes()));
}
if (post.isKeepIfHasComments()) {
builder.append(" and has no comments");
}
return builder.toString();
}
protected String getSuccessReason(Post post, PostScores postScores) {
StringBuilder builder = new StringBuilder();
if (postScores.getScore() >= post.getMinScoreRequired()) {
builder.append("Succeed because ");
builder.append(String.format(SCORE_TEMPLATE,
postScores.getScore(), ">=", post.getMinScoreRequired()));
return builder.toString();
}
if (
(post.getMinTotalVotes() > 0) &&
(postScores.getTotalVotes() >= post.getMinTotalVotes())
) {
builder.append("Succeed because ");
builder.append(String.format(TOTAL_VOTES_TEMPLATE,
postScores.getTotalVotes(), ">=", post.getMinTotalVotes()));
return builder.toString();
}
return "Succeed because has comments";
}
現在，我們將改進舊的邏輯，並記錄這些額外的歷史信息：
private void submitPost(...) {
...
if (errorNode == null) {
post.setSubmissionsResponse(addAttemptResponse(post, "Submitted to Reddit"));
...
} else {
post.setSubmissionsResponse(addAttemptResponse(post, errorNode.toString()));
...
}
}
private void checkAndReSubmit(Post post) {
if (didIntervalPass(...)) {
PostScores postScores = getPostScores(post);
if (didPostGoalFail(post, postScores)) {
...
resetPost(post, getFailReason(post, postScores));
} else {
...
updateLastAttemptResponse(
post, "Post reached target score successfully " +
getSuccessReason(post, postScores));
}
}
}
private void checkAndDeleteInternal(Post post) {
if (didIntervalPass(...)) {
PostScores postScores = getPostScores(post);
if (didPostGoalFail(post, postScores)) {
updateLastAttemptResponse(post,
"Deleted from reddit, consumed all attempts without reaching score " +
getFailReason(post, postScores));
...
} else {
updateLastAttemptResponse(post,
"Post reached target score successfully " +
getSuccessReason(post, postScores));
...
}
}
}
private void resetPost(Post post, String failReason) {
...
updateLastAttemptResponse(post, "Deleted from Reddit, to be resubmitted " + failReason);
...
}請注意低層方法實際執行的操作：
- addAttemptResponse(): 創建一個新的 SubmissionResponse 記錄並將其添加到 Post（在每次提交嘗試時調用）
- updateLastAttemptResponse(): 更新上次嘗試的響應（在檢查 Post 的分數時調用）
4. 計劃發佈DTO
接下來，我們將修改DTO以確保新的信息能夠返回給客户端：
public class ScheduledPostDto {
...
private String status;
private List<SubmissionResponseDto> detailedStatus;
}以下是簡單的 SubmissionResponseDto：
public class SubmissionResponseDto {
private int attemptNumber;
private String content;
private String localSubmissionDate;
private String localScoreCheckDate;
}我們還將修改 ScheduledPostRestController 中的轉換方法：
private ScheduledPostDto convertToDto(Post post) {
...
List<SubmissionResponse> response = post.getSubmissionsResponse();
if ((response != null) && (response.size() > 0)) {
postDto.setStatus(response.get(response.size() - 1).toString().substring(0, 30));
List<SubmissionResponseDto> responsedto =
post.getSubmissionsResponse().stream().
map(res -> generateResponseDto(res)).collect(Collectors.toList());
postDto.setDetailedStatus(responsedto);
} else {
postDto.setStatus("Not sent yet");
postDto.setDetailedStatus(Collections.emptyList());
}
return postDto;
}
private SubmissionResponseDto generateResponseDto(SubmissionResponse responseEntity) {
SubmissionResponseDto dto = modelMapper.map(responseEntity, SubmissionResponseDto.class);
String timezone = userService.getCurrentUser().getPreference().getTimezone();
dto.setLocalSubmissionDate(responseEntity.getSubmissionDate(), timezone);
if (responseEntity.getScoreCheckDate() != null) {
dto.setLocalScoreCheckDate(responseEntity.getScoreCheckDate(), timezone);
}
return dto;
}5. 前端
接下來，我們將修改我們的前端 <em >scheduledPosts.jsp</em > 以處理我們的新響應：
<div class="modal">
<h4 class="modal-title">Detailed Status</h4>
<table id="res"></table>
</div>
<script >
var loadedData = [];
var detailedResTable = $('#res').DataTable( {
"searching":false,
"paging": false,
columns: [
{ title: "Attempt Number", data: "attemptNumber" },
{ title: "Detailed Status", data: "content" },
{ title: "Attempt Submitted At", data: "localSubmissionDate" },
{ title: "Attempt Score Checked At", data: "localScoreCheckDate" }
]
} );
$(document).ready(function() {
$('#myposts').dataTable( {
...
"columnDefs": [
{ "targets": 2, "data": "status",
"render": function ( data, type, full, meta ) {
return data +
' <a href="#" onclick="showDetailedStatus('+meta.row+' )">More Details</a>';
}
},
....
],
...
});
});
function showDetailedStatus(row){
detailedResTable.clear().rows.add(loadedData[row].detailedStatus).draw();
$('.modal').modal();
}
</script>6. 測試
最後，我們將對我們新方法執行一個簡單的單元測試：
首先，我們將測試 getSuccessReason() 實現：
@Test
public void whenHasEnoughScore_thenSucceed() {
Post post = new Post();
post.setMinScoreRequired(5);
PostScores postScores = new PostScores(6, 10, 1);
assertTrue(getSuccessReason(post, postScores).contains("Succeed because score"));
}
@Test
public void whenHasEnoughTotalVotes_thenSucceed() {
Post post = new Post();
post.setMinScoreRequired(5);
post.setMinTotalVotes(8);
PostScores postScores = new PostScores(2, 10, 1);
assertTrue(getSuccessReason(post, postScores).contains("Succeed because total votes"));
}
@Test
public void givenKeepPostIfHasComments_whenHasComments_thenSucceed() {
Post post = new Post();
post.setMinScoreRequired(5);
post.setKeepIfHasComments(true);
final PostScores postScores = new PostScores(2, 10, 1);
assertTrue(getSuccessReason(post, postScores).contains("Succeed because has comments"));
}接下來，我們將測試 getFailReason() 的實現：
@Test
public void whenNotEnoughScore_thenFail() {
Post post = new Post();
post.setMinScoreRequired(5);
PostScores postScores = new PostScores(2, 10, 1);
assertTrue(getFailReason(post, postScores).contains("Failed because score"));
}
@Test
public void whenNotEnoughTotalVotes_thenFail() {
Post post = new Post();
post.setMinScoreRequired(5);
post.setMinTotalVotes(15);
PostScores postScores = new PostScores(2, 10, 1);
String reason = getFailReason(post, postScores);
assertTrue(reason.contains("Failed because score"));
assertTrue(reason.contains("and total votes"));
}
@Test
public void givenKeepPostIfHasComments_whenNotHasComments_thenFail() {
Post post = new Post();
post.setMinScoreRequired(5);
post.setKeepIfHasComments(true);
final PostScores postScores = new PostScores(2, 10, 0);
String reason = getFailReason(post, postScores);
assertTrue(reason.contains("Failed because score"));
assertTrue(reason.contains("and has no comments"));
}7. 結論
在本篇中，我們介紹了 Reddit 帖子生命週期的一些非常有用的信息。現在，我們可以清楚地看到帖子提交和刪除的每個時間點，以及每個操作的具體原因。
