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fix: graceful degradation when plugin not found #63

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fix: graceful degradation when plugin not found #63

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7 changes: 6 additions & 1 deletion paper/src/main/java/net/sabafly/mailBox/database/UserConverter.java
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Original file line number Diff line number Diff line change
Expand Up @@ -30,7 +30,12 @@ public class UserConverter {
if (baseUser == null) {
return null;
}
return baseUser.toUser(uuid, key);
try {
return baseUser.toUser(uuid, key);
} catch (IllegalStateException e) {
// Plugin not found or other state issues - return null gracefully
return null;
}
Comment on lines +33 to +38

@gemini-code-assist gemini-code-assist Bot Jul 19, 2026

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high

Returning null from readUser when a plugin is not found is a great way to handle graceful degradation. However, please note that Base.getAllUsers() (line 304 in Base.java) directly adds the result of readUser(rs) to a list of type List<@NotNull User> without checking for null:

while (rs.next()) {
    users.add(readUser(rs));
}

This will result in null elements being added to a list that is contractually specified to contain only non-null Users, which can lead to unexpected NullPointerExceptions downstream when iterating over the list.

Recommendation:
Please update Base.getAllUsers() to filter out null users before adding them to the list:

User user = readUser(rs);
if (user != null) {
    users.add(user);
}

}

public static byte @NotNull [] toJson(@NotNull User user) {
Expand Down
44 changes: 37 additions & 7 deletions paper/src/main/java/net/sabafly/mailBox/database/impl/Base.java
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Original file line number Diff line number Diff line change
Expand Up @@ -323,13 +323,19 @@ INSERT INTO mailbox_users (uuid, user_data, address) VALUES (?, ?, ?)
UUID id = UUID.fromString(rs.getString("id"));
UUID senderId = Optional.ofNullable(rs.getString("sender")).map(UUID::fromString).orElse(DummyMailUser.SYSTEM_UUID);
User sender = getUser(senderId);
if (sender == null) {
sender = DummyMailUser.createUser(senderId, "Unknown Sender", "unknown", null);
}
UUID receiverId = UUID.fromString(rs.getString("receiver"));
User receiver = getUser(receiverId);
if (receiver == null) {
receiver = DummyMailUser.createUser(receiverId, "Unknown Receiver", "unknown", null);
}
Comment on lines +326 to +333

@gemini-code-assist gemini-code-assist Bot Jul 19, 2026

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critical

Using a hardcoded key value of "unknown" for all fallback DummyMailUsers will cause a database constraint violation.

Why this is an issue:

  1. The mailbox_users table has a UNIQUE constraint on the address column (which stores the user's key): 
    CREATE TABLE IF NOT EXISTS mailbox_users (
    ...
    address TEXT DEFAULT NULL UNIQUE
)
  2. When mail.sender() or mail.receiver() is called (e.g., when rendering mails in the GUI), it triggers database().getOrCreateUser(user).
  3. If the plugin is missing, getUser(uuid) returns null, so getOrCreateUser attempts to update/insert the fallback user into the database.
  4. If multiple fallback users are created with the same key "unknown", the database will attempt to set address = "mailbox:unknown" for multiple rows, violating the UNIQUE constraint and throwing a SQLException. This will crash the mail loading process entirely.

Solution:

Use the user's unique UUID string (e.g., senderId.toString() or receiverId.toString()) as the key value instead of "unknown". Since UUIDs are unique and valid key patterns (containing only lowercase letters, numbers, and hyphens), this completely avoids any database conflicts.

Suggested change
if (sender == null) {
sender = DummyMailUser.createUser(senderId, "Unknown Sender", "unknown", null);
}
UUID receiverId = UUID.fromString(rs.getString("receiver"));
User receiver = getUser(receiverId);
if (receiver == null) {
receiver = DummyMailUser.createUser(receiverId, "Unknown Receiver", "unknown", null);
}
if (sender == null) {
sender = DummyMailUser.createUser(senderId, "Unknown Sender", senderId.toString(), null);
}
UUID receiverId = UUID.fromString(rs.getString("receiver"));
User receiver = getUser(receiverId);
if (receiver == null) {
receiver = DummyMailUser.createUser(receiverId, "Unknown Receiver", receiverId.toString(), null);
}

String title = rs.getString("title");
String content = rs.getString("content");
boolean isRead = rs.getBoolean("is_read");
LocalDateTime sentTime = rs.getTimestamp("sentTime").toLocalDateTime();
Mail mail = new Mail(id, Objects.requireNonNull(sender), Objects.requireNonNull(receiver), title, content, List.of(), isRead, sentTime);
Mail mail = new Mail(id, sender, receiver, title, content, List.of(), isRead, sentTime);
mail.attachments(getMailAttachments(mail));
mails.add(mail);
}
Expand All @@ -344,13 +350,19 @@ INSERT INTO mailbox_users (uuid, user_data, address) VALUES (?, ?, ?)
UUID id = UUID.fromString(rs.getString("id"));
UUID senderId = Optional.ofNullable(rs.getString("sender")).map(UUID::fromString).orElse(DummyMailUser.SYSTEM_UUID);
User sender = getUser(senderId);
if (sender == null) {
sender = DummyMailUser.createUser(senderId, "Unknown Sender", "unknown", null);
}
UUID receiverId = UUID.fromString(rs.getString("receiver"));
User receiver = getUser(receiverId);
if (receiver == null) {
receiver = DummyMailUser.createUser(receiverId, "Unknown Receiver", "unknown", null);
}
Comment on lines +353 to +360

@gemini-code-assist gemini-code-assist Bot Jul 19, 2026

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critical

Using a hardcoded key value of "unknown" for all fallback DummyMailUsers will cause a database constraint violation. Please use the unique UUID string as the key value instead.

Suggested change
if (sender == null) {
sender = DummyMailUser.createUser(senderId, "Unknown Sender", "unknown", null);
}
UUID receiverId = UUID.fromString(rs.getString("receiver"));
User receiver = getUser(receiverId);
if (receiver == null) {
receiver = DummyMailUser.createUser(receiverId, "Unknown Receiver", "unknown", null);
}
if (sender == null) {
sender = DummyMailUser.createUser(senderId, "Unknown Sender", senderId.toString(), null);
}
UUID receiverId = UUID.fromString(rs.getString("receiver"));
User receiver = getUser(receiverId);
if (receiver == null) {
receiver = DummyMailUser.createUser(receiverId, "Unknown Receiver", receiverId.toString(), null);
}

String title = rs.getString("title");
String content = rs.getString("content");
boolean isRead = rs.getBoolean("is_read");
LocalDateTime sentTime = rs.getTimestamp("sentTime").toLocalDateTime();
Mail mail = new Mail(id, Objects.requireNonNull(sender), Objects.requireNonNull(receiver), title, content, List.of(), isRead, sentTime);
Mail mail = new Mail(id, sender, receiver, title, content, List.of(), isRead, sentTime);
mail.attachments(getMailAttachments(mail));
mails.add(mail);
}
Expand Down Expand Up @@ -396,13 +408,19 @@ public int countMails(@NotNull User user, @NotNull TriState read) {
if (rs.next()) {
UUID senderId = Optional.ofNullable(rs.getString("sender")).map(UUID::fromString).orElse(DummyMailUser.SYSTEM_UUID);
User sender = getUser(senderId);
if (sender == null) {
sender = DummyMailUser.createUser(senderId, "Unknown Sender", "unknown", null);
}
UUID receiverId = UUID.fromString(rs.getString("receiver"));
User receiver = getUser(receiverId);
if (receiver == null) {
receiver = DummyMailUser.createUser(receiverId, "Unknown Receiver", "unknown", null);
}
Comment on lines +411 to +418

@gemini-code-assist gemini-code-assist Bot Jul 19, 2026

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critical

Using a hardcoded key value of "unknown" for all fallback DummyMailUsers will cause a database constraint violation. Please use the unique UUID string as the key value instead.

Suggested change
if (sender == null) {
sender = DummyMailUser.createUser(senderId, "Unknown Sender", "unknown", null);
}
UUID receiverId = UUID.fromString(rs.getString("receiver"));
User receiver = getUser(receiverId);
if (receiver == null) {
receiver = DummyMailUser.createUser(receiverId, "Unknown Receiver", "unknown", null);
}
if (sender == null) {
sender = DummyMailUser.createUser(senderId, "Unknown Sender", senderId.toString(), null);
}
UUID receiverId = UUID.fromString(rs.getString("receiver"));
User receiver = getUser(receiverId);
if (receiver == null) {
receiver = DummyMailUser.createUser(receiverId, "Unknown Receiver", receiverId.toString(), null);
}

String title = rs.getString("title");
String content = rs.getString("content");
boolean read = rs.getBoolean("is_read");
LocalDateTime sentTime = rs.getTimestamp("sentTime").toLocalDateTime();
Mail mail = new Mail(id, Objects.requireNonNull(sender), Objects.requireNonNull(receiver), title, content, List.of(), read, sentTime);
Mail mail = new Mail(id, sender, receiver, title, content, List.of(), read, sentTime);
mail.attachments(getMailAttachments(mail));
return mail;
}
Expand Down Expand Up @@ -490,11 +508,14 @@ public void updateMailTemplate(@NotNull MailTemplate template) {
boolean autoSend = rs.getBoolean("auto_send");
UUID senderId = Optional.ofNullable(rs.getString("sender")).map(UUID::fromString).orElse(null);
User sender = getUser(senderId);
if (sender == null) {
sender = DummyMailUser.createUser(senderId != null ? senderId : DummyMailUser.SYSTEM_UUID, "Unknown Sender", "unknown", null);
}
Comment on lines +511 to +513

@gemini-code-assist gemini-code-assist Bot Jul 19, 2026

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critical

Using a hardcoded key value of "unknown" for all fallback DummyMailUsers will cause a database constraint violation. Please use the unique UUID string as the key value instead.

Suggested change
if (sender == null) {
sender = DummyMailUser.createUser(senderId != null ? senderId : DummyMailUser.SYSTEM_UUID, "Unknown Sender", "unknown", null);
}
if (sender == null) {
UUID fallbackId = senderId != null ? senderId : DummyMailUser.SYSTEM_UUID;
sender = DummyMailUser.createUser(fallbackId, "Unknown Sender", fallbackId.toString(), null);
}

Date startTime = rs.getTimestamp("start_time");
Date endTime = rs.getTimestamp("end_time");
Duration interval = Optional.of(rs.getLong("send_interval")).filter(l -> l > 0).map(Duration::ofSeconds).orElse(null);
String permission = rs.getString("permission");
MailTemplate template = new MailTemplate(id, title, content, List.of(), autoSend, Objects.requireNonNull(sender), LocalDateTime.ofInstant(startTime.toInstant(), ZoneId.systemDefault()), LocalDateTime.ofInstant(endTime.toInstant(), ZoneId.systemDefault()), interval, permission);
MailTemplate template = new MailTemplate(id, title, content, List.of(), autoSend, sender, LocalDateTime.ofInstant(startTime.toInstant(), ZoneId.systemDefault()), LocalDateTime.ofInstant(endTime.toInstant(), ZoneId.systemDefault()), interval, permission);
template.setAttachment(getTemplateAttachments(template));
return template;
}
Expand All @@ -520,11 +541,14 @@ public void updateMailTemplate(@NotNull MailTemplate template) {
boolean autoSend = rs.getBoolean("auto_send");
UUID senderId = Optional.ofNullable(rs.getString("sender")).map(UUID::fromString).orElse(null);
User sender = getUser(senderId);
if (sender == null) {
sender = DummyMailUser.createUser(senderId != null ? senderId : DummyMailUser.SYSTEM_UUID, "Unknown Sender", "unknown", null);
}
Comment on lines +544 to +546

@gemini-code-assist gemini-code-assist Bot Jul 19, 2026

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critical

Using a hardcoded key value of "unknown" for all fallback DummyMailUsers will cause a database constraint violation. Please use the unique UUID string as the key value instead.

Suggested change
if (sender == null) {
sender = DummyMailUser.createUser(senderId != null ? senderId : DummyMailUser.SYSTEM_UUID, "Unknown Sender", "unknown", null);
}
if (sender == null) {
UUID fallbackId = senderId != null ? senderId : DummyMailUser.SYSTEM_UUID;
sender = DummyMailUser.createUser(fallbackId, "Unknown Sender", fallbackId.toString(), null);
}

@Nullable LocalDateTime startTime = Optional.ofNullable(rs.getTimestamp("start_time")).map(timestamp -> LocalDateTime.ofInstant(timestamp.toInstant(), ZoneId.systemDefault())).orElse(null);
@Nullable LocalDateTime endTime = Optional.ofNullable(rs.getTimestamp("end_time")).map(timestamp -> LocalDateTime.ofInstant(timestamp.toInstant(), ZoneId.systemDefault())).orElse(null);
@Nullable Duration interval = Optional.of(rs.getLong("send_interval")).filter(l -> l > 0).map(Duration::ofSeconds).orElse(null);
@Nullable String permission = rs.getString("permission");
MailTemplate template = new MailTemplate(id, title, content, List.of(), autoSend, Objects.requireNonNull(sender), startTime, endTime, interval, permission);
MailTemplate template = new MailTemplate(id, title, content, List.of(), autoSend, sender, startTime, endTime, interval, permission);
template.setAttachment(getTemplateAttachments(template));
templates.add(template);
}
Expand All @@ -550,11 +574,14 @@ public void updateMailTemplate(@NotNull MailTemplate template) {
boolean autoSend = rs.getBoolean("auto_send");
UUID senderId = Optional.ofNullable(rs.getString("sender")).map(UUID::fromString).orElse(null);
User sender1 = getUser(senderId);
if (sender1 == null) {
sender1 = DummyMailUser.createUser(senderId != null ? senderId : DummyMailUser.SYSTEM_UUID, "Unknown Sender", "unknown", null);
}
Comment on lines +577 to +579

@gemini-code-assist gemini-code-assist Bot Jul 19, 2026

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critical

Using a hardcoded key value of "unknown" for all fallback DummyMailUsers will cause a database constraint violation. Please use the unique UUID string as the key value instead.

Suggested change
if (sender1 == null) {
sender1 = DummyMailUser.createUser(senderId != null ? senderId : DummyMailUser.SYSTEM_UUID, "Unknown Sender", "unknown", null);
}
if (sender1 == null) {
UUID fallbackId = senderId != null ? senderId : DummyMailUser.SYSTEM_UUID;
sender1 = DummyMailUser.createUser(fallbackId, "Unknown Sender", fallbackId.toString(), null);
}

@Nullable LocalDateTime startTime = Optional.ofNullable(rs.getTimestamp("start_time")).map(timestamp -> LocalDateTime.ofInstant(timestamp.toInstant(), ZoneId.systemDefault())).orElse(null);
@Nullable LocalDateTime endTime = Optional.ofNullable(rs.getTimestamp("end_time")).map(timestamp -> LocalDateTime.ofInstant(timestamp.toInstant(), ZoneId.systemDefault())).orElse(null);
@Nullable Duration interval = Optional.of(rs.getLong("send_interval")).filter(l -> l > 0).map(Duration::ofSeconds).orElse(null);
@Nullable String permission = rs.getString("permission");
MailTemplate template = new MailTemplate(id, title, content, List.of(), autoSend, Objects.requireNonNull(sender1), startTime, endTime, interval, permission);
MailTemplate template = new MailTemplate(id, title, content, List.of(), autoSend, sender1, startTime, endTime, interval, permission);
template.setAttachment(getTemplateAttachments(template));
templates.add(template);
}
Expand All @@ -580,11 +607,14 @@ public void updateMailTemplate(@NotNull MailTemplate template) {
boolean autoSend = rs.getBoolean("auto_send");
UUID senderId = Optional.ofNullable(rs.getString("sender")).map(UUID::fromString).orElse(DummyMailUser.SYSTEM_UUID);
User sender = getUser(senderId);
if (sender == null) {
sender = DummyMailUser.createUser(senderId, "Unknown Sender", "unknown", null);
}
Comment on lines +610 to +612

@gemini-code-assist gemini-code-assist Bot Jul 19, 2026

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critical

Using a hardcoded key value of "unknown" for all fallback DummyMailUsers will cause a database constraint violation. Please use the unique UUID string as the key value instead.

Suggested change
if (sender == null) {
sender = DummyMailUser.createUser(senderId, "Unknown Sender", "unknown", null);
}
if (sender == null) {
sender = DummyMailUser.createUser(senderId, "Unknown Sender", senderId.toString(), null);
}

@Nullable LocalDateTime startTime = rs.getTimestamp("start_time") == null ? null : LocalDateTime.ofInstant(rs.getTimestamp("start_time").toInstant(), ZoneId.systemDefault());
@Nullable LocalDateTime endTime = rs.getTimestamp("end_time") == null ? null : LocalDateTime.ofInstant(rs.getTimestamp("end_time").toInstant(), ZoneId.systemDefault());
@Nullable Duration interval = Optional.of(rs.getLong("send_interval")).filter(l -> l > 0).map(Duration::ofSeconds).orElse(null);
@Nullable String permission = rs.getString("permission");
MailTemplate template = new MailTemplate(id, title, content, List.of(), autoSend, Objects.requireNonNull(sender), startTime, endTime, interval, permission);
MailTemplate template = new MailTemplate(id, title, content, List.of(), autoSend, sender, startTime, endTime, interval, permission);
template.setAttachment(getTemplateAttachments(template));
templates.add(template);
}
Expand Down