From 4f05ed1dd7a9b3eb831efcccd5fe9ebe53cb37d7 Mon Sep 17 00:00:00 2001
From: Alessandro Pasotti <elpaso@itopen.it>
Date: Thu, 15 Mar 2018 15:11:52 +0100
Subject: [PATCH] [bugfix] value relation widget with Allow multiple selection
 doesn't resolve

Now it will accept arrays as well as string representations of arrays

Added a test

Fixes #16967 value relation widget with Allow multiple selection doesn't resolve the values anymore
---
 .../qgsvaluerelationfieldformatter.sip.in     | 11 ++++++++++
 .../qgsvaluerelationfieldformatter.cpp        | 22 ++++++++++++++++++-
 .../qgsvaluerelationfieldformatter.h          |  9 ++++++++
 .../qgsvaluerelationwidgetwrapper.cpp         |  6 +----
 tests/src/python/test_qgsfieldformatters.py   | 10 +++++++++
 5 files changed, 52 insertions(+), 6 deletions(-)

diff --git a/python/core/fieldformatter/qgsvaluerelationfieldformatter.sip.in b/python/core/fieldformatter/qgsvaluerelationfieldformatter.sip.in
index 2c761f352b3..e9a1d00d09a 100644
--- a/python/core/fieldformatter/qgsvaluerelationfieldformatter.sip.in
+++ b/python/core/fieldformatter/qgsvaluerelationfieldformatter.sip.in
@@ -63,6 +63,17 @@ This can be used to keep the value map in the local memory
 if doing multiple lookups in a loop.
 
 .. versionadded:: 3.0
+%End
+
+    static QStringList valueToStringList( const QVariant &value );
+%Docstring
+Utility to convert an array or a string representation of and array ``value`` to a string list
+
+:param value: The value to be converted
+
+:return: A string list
+
+.. versionadded:: 3.2
 %End
 };
 
diff --git a/src/core/fieldformatter/qgsvaluerelationfieldformatter.cpp b/src/core/fieldformatter/qgsvaluerelationfieldformatter.cpp
index c411fcff7ff..4df6a75c08b 100644
--- a/src/core/fieldformatter/qgsvaluerelationfieldformatter.cpp
+++ b/src/core/fieldformatter/qgsvaluerelationfieldformatter.cpp
@@ -54,7 +54,7 @@ QString QgsValueRelationFieldFormatter::representValue( QgsVectorLayer *layer, i
 
   if ( config.value( QStringLiteral( "AllowMulti" ) ).toBool() )
   {
-    QStringList keyList = value.toString().remove( QChar( '{' ) ).remove( QChar( '}' ) ).split( ',' );
+    QStringList keyList = valueToStringList( value );
     QStringList valueList;
 
     for ( const QgsValueRelationFieldFormatter::ValueRelationItem &item : qgis::as_const( vrCache ) )
@@ -142,3 +142,23 @@ QgsValueRelationFieldFormatter::ValueRelationCache QgsValueRelationFieldFormatte
 
   return cache;
 }
+
+QStringList QgsValueRelationFieldFormatter::valueToStringList( const QVariant &value )
+{
+  QStringList checkList;
+  if ( value.type() == QVariant::StringList )
+    checkList = value.toStringList();
+  else if ( value.type() == QVariant::String )
+    checkList = value.toString().remove( QChar( '{' ) ).remove( QChar( '}' ) ).split( ',' );
+  else if ( value.type() == QVariant::List )
+  {
+    QVariantList valuesList( value.toList( ) );
+    for ( const QVariant &listItem : qgis::as_const( valuesList ) )
+    {
+      QString v( listItem.toString( ) );
+      if ( ! v.isEmpty() )
+        checkList.append( v );
+    }
+  }
+  return checkList;
+}
diff --git a/src/core/fieldformatter/qgsvaluerelationfieldformatter.h b/src/core/fieldformatter/qgsvaluerelationfieldformatter.h
index 7c67f8338cb..9840b09d76d 100644
--- a/src/core/fieldformatter/qgsvaluerelationfieldformatter.h
+++ b/src/core/fieldformatter/qgsvaluerelationfieldformatter.h
@@ -70,6 +70,15 @@ class CORE_EXPORT QgsValueRelationFieldFormatter : public QgsFieldFormatter
      * \since QGIS 3.0
      */
     static QgsValueRelationFieldFormatter::ValueRelationCache createCache( const QVariantMap &config );
+
+    /**
+     * Utility to convert an array or a string representation of and array \a value to a string list
+     *
+     * \param value The value to be converted
+     * \return A string list
+     * \since QGIS 3.2
+     */
+    static QStringList valueToStringList( const QVariant &value );
 };
 
 Q_DECLARE_METATYPE( QgsValueRelationFieldFormatter::ValueRelationCache )
diff --git a/src/gui/editorwidgets/qgsvaluerelationwidgetwrapper.cpp b/src/gui/editorwidgets/qgsvaluerelationwidgetwrapper.cpp
index 53dec6ebffa..b6f49a50215 100644
--- a/src/gui/editorwidgets/qgsvaluerelationwidgetwrapper.cpp
+++ b/src/gui/editorwidgets/qgsvaluerelationwidgetwrapper.cpp
@@ -151,11 +151,7 @@ void QgsValueRelationWidgetWrapper::setValue( const QVariant &value )
 {
   if ( mListWidget )
   {
-    QStringList checkList;
-    if ( value.type() == QVariant::StringList )
-      checkList = value.toStringList();
-    else if ( value.type() == QVariant::String )
-      checkList = value.toString().remove( QChar( '{' ) ).remove( QChar( '}' ) ).split( ',' );
+    QStringList checkList( QgsValueRelationFieldFormatter::valueToStringList( value ) );
 
     for ( int i = 0; i < mListWidget->count(); ++i )
     {
diff --git a/tests/src/python/test_qgsfieldformatters.py b/tests/src/python/test_qgsfieldformatters.py
index b72af0d7fdd..def96b185e1 100644
--- a/tests/src/python/test_qgsfieldformatters.py
+++ b/tests/src/python/test_qgsfieldformatters.py
@@ -107,6 +107,16 @@ class TestQgsValueRelationFieldFormatter(unittest.TestCase):
 
         QgsProject.instance().removeMapLayer(second_layer.id())
 
+    def test_valueToStringList(self):
+
+        def _test(a, b):
+            self.assertEqual(QgsValueRelationFieldFormatter.valueToStringList(a), b)
+
+        _test([1, 2, 3], ["1", "2", "3"])
+        _test("{1,2,3}", ["1", "2", "3"])
+        _test(['1', '2', '3'], ["1", "2", "3"])
+        _test('not an array', ['not an array'])
+
 
 class TestQgsRelationReferenceFieldFormatter(unittest.TestCase):