path: root/src/corelib/itemmodels/qabstractitemmodel.h
diff options
authorGiuseppe D'Angelo <>2017-09-01 18:27:15 +0200
committerGiuseppe D'Angelo <>2018-01-08 09:41:53 +0000
commit69496d4e22fb6a8805fbcfa798d9aca53621a2ac (patch)
tree788bb62a9981188fb82ad16ef61b1e9e8fdeb35d /src/corelib/itemmodels/qabstractitemmodel.h
parent9c53f4d33a1953bc84e5b5e8bbef14db375bb180 (diff)
Introduce QAbstractItemModel::checkIndex()
When implementing a custom model there's the habit, in each and every function that takes a QModelIndex, to carefully checking the index passed by the caller. This index is checked for "legality" (*): does the index belong to this model, is the index pointing to an existing row and column, and so on. These checks are hand-rolled and, as such, slightly different and possibly incomplete (i.e. wrong) every time. What's worse, these checks are implemented via "ordinary" code (if statements). However, passing an illegal index to a QAIM function is a precondition violation, and as such does not (and must not) be checked in ordinary conditions, as it triggers undefined behavior. On the other hand, while debugging a custom model or a custom hierarchy of (proxy) models, having such checks in place can be a significant aid. Enter checkIndex(): a debugging helper for QAbstractItemModel and its subclasses. checkIndex() centralizes the checks for legality of a given index. User code is free to assert on it, or have some other fallback mechanism in case a check fails. (*) Using "legality" here instead of "validity" in order to avoid confusion between QModelIndex::isValid() and what checkIndex() really does. [ChangeLog][QtCore][QAbstractItemModel] Added QAbstractItemModel::checkIndex(), a debugging function for QAbstractItemModel subclasses. Change-Id: I1eea0586b1ac3ededdbfbf46759145022dc5ad86 Reviewed-by: Thorbjørn Lund Martsum <> Reviewed-by: David Faure <>
Diffstat (limited to 'src/corelib/itemmodels/qabstractitemmodel.h')
1 files changed, 13 insertions, 0 deletions
diff --git a/src/corelib/itemmodels/qabstractitemmodel.h b/src/corelib/itemmodels/qabstractitemmodel.h
index cd294ef8fa..621f284c34 100644
--- a/src/corelib/itemmodels/qabstractitemmodel.h
+++ b/src/corelib/itemmodels/qabstractitemmodel.h
@@ -250,6 +250,17 @@ public:
+ enum class CheckIndexOption {
+ NoOption = 0x0000,
+ IndexIsValid = 0x0001,
+ DoNotUseParent = 0x0002,
+ ParentIsInvalid = 0x0004,
+ };
+ Q_ENUM(CheckIndexOption)
+ Q_DECLARE_FLAGS(CheckIndexOptions, CheckIndexOption)
+ Q_REQUIRED_RESULT bool checkIndex(const QModelIndex &index, CheckIndexOptions options = CheckIndexOption::NoOption) const;
void dataChanged(const QModelIndex &topLeft, const QModelIndex &bottomRight, const QVector<int> &roles = QVector<int>());
void headerDataChanged(Qt::Orientation orientation, int first, int last);
@@ -343,6 +354,8 @@ private:
inline bool QAbstractItemModel::insertRow(int arow, const QModelIndex &aparent)
{ return insertRows(arow, 1, aparent); }
inline bool QAbstractItemModel::insertColumn(int acolumn, const QModelIndex &aparent)