如何在子节点下插入到实时数据库？

huangapple
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英文:

How to insert to Realtime Database under the child?

问题

如何在Java中编写代码来创建像图像中的实例？我正在尝试创建它，但它只会插入到"Teacher"父项下面。

以下是我正在尝试编写的代码。

  1. FirebaseDatabase.getInstance().getReference("Teachers").child("Accounts")
  2.     .setValue(dataClass).addOnCompleteListener(new OnCompleteListener<Void>() {
  3.         @Override
  4.         public void onComplete(@NonNull Task<Void> task) {
  5.             if (task.isSuccessful()) {
  6.                 Toast.makeText(AddSection.this, "Section added successfully", Toast.LENGTH_SHORT).show();
  7.                 finish();
  8.             }
  9.         }
  10.     }).addOnFailureListener(new OnFailureListener() {
  11.         @Override
  12.         public void onFailure(@NonNull Exception e) {
  13.             Toast.makeText(AddSection.this, e.getMessage().toString(), Toast.LENGTH_SHORT).show();
  14.         }
  15.     });
  16. }
英文:

如何在子节点下插入到实时数据库？

How do I do the code in Java to create an instance like in the image? I am trying to create that but it only inserts under the Teacher parent.

Below is the code that I am trying to do.

  1. FirebaseDatabase.getInstance().getReference(&quot;Teachers&quot;).child(&quot;Accounts&quot;)
  2.     .setValue(dataClass).addOnCompleteListener(new OnCompleteListener&lt;Void&gt;() {
  3.         @Override
  4.         public void onComplete(@NonNull Task&lt;Void&gt; task) {
  5.             if (task.isSuccessful()) {
  6.                 Toast.makeText(AddSection.this, &quot;Section added successfully&quot;, Toast.LENGTH_SHORT).show();
  7.                 finish();
  8.             }
  9.         }
  10.     }).addOnFailureListener(new OnFailureListener() {
  11.         @Override
  12.         public void onFailure(@NonNull Exception e) {
  13.             Toast.makeText(AddSection.this, e.getMessage().toString(), Toast.LENGTH_SHORT).show();
  14.         }
  15.     });
  16. }

答案1

得分: 1

  1. 如果您想要在类似以下结构中添加新的子项：
  3.     db
  4.     |
  5.     --- 教师
  6.          |
  7.          --- 帐户
  8.               |
  9.               --- 0000-123455
  10.                    |
  11.                    --- 部分
  12.                         |
  13.                         --- BSIT201A
  14.                              |
  15.                              --- 学生
  16.                              |    |
  17.                              |    --- studentName: "Joseph"
  18.                              |
  19.                              --- pSectionName: "BSIT201A"
  20.                              |
  21.                              --- subject: "Subject Name" //&#128072; 新添加的。
  23. 然后，您需要创建一个指向"BSIT201A"节点的引用，并调用[updateChildren()][1]，就像以下代码行一样：
  25.     DatabaseReference db = FirebaseDatabase.getInstance().getReference();
  26.     DatabaseReference secNameRef = db.child("Teachers/Accounts/0000-123455/Sections/BSIT201A");
  27.     Map<String, Object> update = new HashMap<>();
  28.     update.put("subject", "Subject Name");
  29.     secNameRef.updateChildren(update);
  31. 我还建议您将一个完整的监听器附加到updateChildren()操作，以查看是否出现问题。
  33.   [1]: https://firebase.google.com/docs/reference/android/com/google/firebase/database/DatabaseReference#updateChildren(java.util.Map%3Cjava.lang.String,java.lang.Object%3E)
英文:

If you want to add a new child in a structure that looks like this:

  1. db
  2. |
  3. --- Teachers
  4.      |
  5.      --- Accounts
  6.           |
  7.           --- 0000-123455
  8.                |
  9.                --- Sections
  10.                     |
  11.                     --- BSIT201A
  12.                          |
  13.                          --- Students
  14.                          |    |
  15.                          |    --- studentName: &quot;Joseph&quot;
  16.                          |
  17.                          --- pSectionName: &quot;BSIT201A&quot;
  18.                          |
  19.                          --- subject: &quot;Subject Name&quot; //&#128072; Newly added.

Then you have to create a reference that points to the BSIT201A node and call updateChildren(), like in the following lines of code:

  1. DatabaseReference db = FirebaseDatabase.getInstance().getReference();
  2. DatabaseReference secNameRef = db.child(&quot;Teachers/Accounts/0000-123455/Sections/BSIT201A&quot;);
  3. Map&lt;String, Object&gt; update = new HashMap&lt;&gt;();
  4. update.put(&quot;subject&quot;, &quot;Subject Name&quot;);
  5. secNameRef.updateChildren(update);

I also recommend you attach a complete listener to the updateChildren() operation, to see if something goes wrong.

huangapple
  • 本文由 发表于 2023年2月24日 15:01:27
  • 转载请务必保留本文链接：https://go.coder-hub.com/75553460.html
  • android
  • firebase
  • firebase-realtime-database
  • java
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