Merge bitcoin-core/gui#173: Follow Qt docs when implementing rowCount and columnCount

195fcb53a0 qt: Follow Qt docs when implementing rowCount and columnCount (Hennadii Stepanov)

Pull request description:

  [`QAbstractItemModel::rowCount`](https://doc.qt.io/qt-5/qabstractitemmodel.html#rowCount):
  > **Note:** When implementing a table based model, `rowCount()` should return 0 when the parent is valid.

  [`QAbstractItemModel::columnCount`](https://doc.qt.io/qt-5/qabstractitemmodel.html#columnCount):
  > **Note:** When implementing a table based model, `columnCount()` should return 0 when the parent is valid.

ACKs for top commit:
  jarolrod:
    Tested ACK 195fcb53a0. Compiled and ran on macOS (Big Sur 11.1 and Catalina 10.15.7), Arch Linux, and FreeBSD. visually verified no weird effects with the `Address`, `Ban`, `Peer`, and `Transaction` tables. As already stated, the code change brings us inline with what the QT Docs recommend.

Tree-SHA512: 179a3430e68e77b22cdf642964cd96c023a2286ee256bbeb25b43df3d2eef6f59978c8d92173c6be5071d127fdcd6aa338142f6eaf003ff08e4abd65172d20ca

src/qt/addresstablemodel.cpp

@@ -177,13 +177,17 @@ AddressTableModel::~AddressTableModel()
 
 int AddressTableModel::rowCount(const QModelIndex &parent) const
 {
-    Q_UNUSED(parent);
+    if (parent.isValid()) {
+        return 0;
+    }
     return priv->size();
 }
 
 int AddressTableModel::columnCount(const QModelIndex &parent) const
 {
-    Q_UNUSED(parent);
+    if (parent.isValid()) {
+        return 0;
+    }
     return columns.length();
 }
 

src/qt/bantablemodel.cpp

@@ -98,13 +98,17 @@ BanTableModel::~BanTableModel()
 
 int BanTableModel::rowCount(const QModelIndex &parent) const
 {
-    Q_UNUSED(parent);
+    if (parent.isValid()) {
+        return 0;
+    }
     return priv->size();
 }
 
 int BanTableModel::columnCount(const QModelIndex &parent) const
 {
-    Q_UNUSED(parent);
+    if (parent.isValid()) {
+        return 0;
+    }
     return columns.length();
 }
 

src/qt/peertablemodel.cpp

@@ -134,13 +134,17 @@ void PeerTableModel::stopAutoRefresh()
 
 int PeerTableModel::rowCount(const QModelIndex &parent) const
 {
-    Q_UNUSED(parent);
+    if (parent.isValid()) {
+        return 0;
+    }
     return priv->size();
 }
 
 int PeerTableModel::columnCount(const QModelIndex &parent) const
 {
-    Q_UNUSED(parent);
+    if (parent.isValid()) {
+        return 0;
+    }
     return columns.length();
 }
 

src/qt/recentrequeststablemodel.cpp

@@ -36,15 +36,17 @@ RecentRequestsTableModel::~RecentRequestsTableModel()
 
 int RecentRequestsTableModel::rowCount(const QModelIndex &parent) const
 {
-    Q_UNUSED(parent);
-
+    if (parent.isValid()) {
+        return 0;
+    }
     return list.length();
 }
 
 int RecentRequestsTableModel::columnCount(const QModelIndex &parent) const
 {
-    Q_UNUSED(parent);
-
+    if (parent.isValid()) {
+        return 0;
+    }
     return columns.length();
 }
 

src/qt/transactiontablemodel.cpp

@@ -289,13 +289,17 @@ void TransactionTableModel::updateConfirmations()
 
 int TransactionTableModel::rowCount(const QModelIndex &parent) const
 {
-    Q_UNUSED(parent);
+    if (parent.isValid()) {
+        return 0;
+    }
     return priv->size();
 }
 
 int TransactionTableModel::columnCount(const QModelIndex &parent) const
 {
-    Q_UNUSED(parent);
+    if (parent.isValid()) {
+        return 0;
+    }
     return columns.length();
 }