我了解到Cloud Firestore不会自动按顺序对数据进行排序。我创建了一个值,该值本质上是转换为小时的时期。我想按此值为查询排序数据:
Query queryStore = FirebaseFirestore.getInstance()
.collection(POLLS_LABEL)
.orderBy("epoch", Query.Direction.DESCENDING);
我发现我的数据没有按我希望的那样排序。不确定是否需要在代码中添加特殊注释,但是我可以想象它和上面一样简单。下面是我的模型:
@com.google.firebase.firestore.IgnoreExtraProperties
public class Poll {
private String question;
private String image_URL;
private String user_ID;
private String display_name;
private int vote_count;
private Long epoch;
private long trend_score;
@ServerTimestamp
private Date date;
private ArrayList<String> answers;
public Poll() {
}
public Poll(String Question, String Image_URL, ArrayList<String> answers, int vote_count, String UserID, String DisplayName, Long epoch, long trend_score, Date date
) {
this.question = Question;
this.image_URL = Image_URL;
this.answers = answers;
this.vote_count = vote_count;
this.user_ID = UserID;
this.display_name = DisplayName;
this.epoch = epoch;
this.trend_score = trend_score;
this.date = date;
}
public String getUser_id() {
return user_ID;
}
public String getDisplay_name() {
return display_name;
}
public String getQuestion() {
return question;
}
public void setQuestion(String question) {
this.question = question;
}
public String getImage_URL() {
return image_URL;
}
public Long getEpoch() {
return epoch;
}
public void setEpoch(Long epoch) {
this.epoch = epoch;
}
public void setUser_id(String user_id) {
this.user_ID = user_id;
}
public void setDisplay_name(String display_name) {
this.display_name = display_name;
}
public void setImage_URL(String image_URL) {
this.image_URL = image_URL;
}
public Integer getVote_count() {
return vote_count;
}
public void setVote_count(Integer vote_count) {
this.vote_count = vote_count;
}
public long getTrend_score() {
return trend_score;
}
public void setTrend_score(long trend_score) {
this.trend_score = trend_score;
}
@Exclude
public Map<String, Object> toMap() {
HashMap<String, Object> result = new HashMap<>();
result.put("question", question);
result.put("image_URL", image_URL);
result.put("vote_count", 0);
result.put("user_ID", user_ID);
result.put("display_name", display_name);
result.put("epoch", epoch);
result.put("trend_score", trend_score);
return result;
}
创作:
final Poll poll = new Poll(mCreatePollQuestion.getText().toString(), resultImageURL, mPollAnswers, 0, ID, displayName, currentEpoch, intialQS, FieldValue.serverTimestamp());
添加到Firestore:
mStoreBaseRef.collection(POLLS).add(poll).addOnCompleteListener(new OnCompleteListener<DocumentReference>() {
@Override
public void onComplete(@NonNull Task<DocumentReference> task) {
if (task.isSuccessful()) {
DocumentReference docRef = task.getResult();
String key = docRef.getId();
Log.v("KEY", key);
Toast.makeText(getApplicationContext(), key, Toast.LENGTH_LONG).show();
CollectionReference pollAnswerRef = mStoreBaseRef.collection("Polls").document(key).collection("answers");
//TODO: need to add answers
for (int i = 0; i < mPollAnswers.size(); i++){
pollAnswerRef.document(String.valueOf(i + 1)).set((poll.answerConvert(mPollAnswers, i)), SetOptions.merge());
}
}
}
答案 0 :(得分:1)
您猜对了,应该使用注释,但是您的epoch
对象应该不是类型为Long
,而是Date
。因此,在您的Poll
类中,请更改以下代码行:
private Long epoch;
到
@ServerTimestamp
private Date date;
我将那个date
对象命名为 date ,因为对象的类型是Date
,现在不是并且了。创建Pool
类的对象时,无需设置日期。 Firebase服务器将读取您的日期字段,因为它是ServerTimestamp
(请参见注释),并且将相应地使用服务器时间戳填充该日期字段。
添加日期的另一种方法是使用Map
和FieldValue.serverTimestamp(),如下所示:
Map<String, Object> map = new HashMap<>();
map.put("date", FieldValue.serverTimestamp());
docRef.update(map).addOnCompleteListener(new OnCompleteListener<Void>() {/* ... */}