[FEATURE ] allow to use URLs for attribute forms

Author: 3nids

python/core/qgseditformconfig.sip.in

@@ -64,6 +64,12 @@ Constructor for TabData
       CodeSourceEnvironment
     };
 
+    enum FormPath
+    {
+      Original,
+      LocalCopy
+    };
+
     QgsEditFormConfig( const QgsEditFormConfig &o );
 %Docstring
 Copy constructor
@@ -109,17 +115,21 @@ Get the active layout style for the attribute editor for this layer
 Set the active layout style for the attribute editor for this layer
 %End
 
-    QString uiForm() const;
+    QString uiForm( FormPath path = LocalCopy ) const;
 %Docstring
-Get path to the .ui form. Only meaningful with EditorLayout.UiFileLayout.
+ Get path to the .ui form. Only meaningful with EditorLayout.UiFileLayout
+If the form is from a URL and ``path`` is Original, the original URL
+of the UI form is returned instead of the local copy.
 %End
 
-    void setUiForm( const QString &ui );
+    bool setUiForm( const QString &ui, QString *errMsg /Out/ = 0 );
 %Docstring
 Set path to the .ui form.
-When a string is provided, the layout style will be set to EditorLayout.UiFileLayout,
+When a string is provided in ``ui``, the layout style will be set to EditorLayout.UiFileLayout,
 if an empty or a null string is provided, the layout style will be set to
 EditorLayout.GeneratedLayout.
+If ``ui`` is a URL, a local copy of the file will be made and will be used to create the forms
+``context`` is provided to save error messages
 %End
 
     bool setWidgetConfig( const QString &widgetName, const QVariantMap &config );

python/core/qgsproject.sip.in

@@ -930,6 +930,16 @@ provider.
 Returns the current auxiliary storage.
 
 .. versionadded:: 3.0
+%End
+
+    void addUiFormLocalCopy( QTemporaryFile *file );
+%Docstring
+Save a pointer to temporary file to keep local copy
+available of downloaded UI forms during project's life
+
+:param file: the pointer to the temporary file
+
+.. versionadded:: 3.2
 %End
 
     const QgsProjectMetadata &metadata() const;

src/app/qgsattributesformproperties.cpp

@@ -17,6 +17,7 @@
 #include "qgsattributetypedialog.h"
 #include "qgsattributerelationedit.h"
 #include "qgsattributesforminitcode.h"
+#include "qgisapp.h"
 
 QgsAttributesFormProperties::QgsAttributesFormProperties( QgsVectorLayer *layer, QWidget *parent )
   : QWidget( parent )
@@ -168,7 +169,7 @@ void QgsAttributesFormProperties::initLayoutConfig()
   mEditorLayoutComboBox_currentIndexChanged( mEditorLayoutComboBox->currentIndex() );
 
   QgsEditFormConfig cfg = mLayer->editFormConfig();
-  mEditFormLineEdit->setText( cfg.uiForm() );
+  mEditFormLineEdit->setText( cfg.uiForm( QgsEditFormConfig::Original ) );
 }
 
 void QgsAttributesFormProperties::initInitPython()
@@ -683,7 +684,9 @@ void QgsAttributesFormProperties::apply()
     editFormConfig.addTab( createAttributeEditorWidget( tabItem, nullptr, false ) );
   }
 
-  editFormConfig.setUiForm( mEditFormLineEdit->text() );
+  QString *errMsg = new QString();
+  if ( !editFormConfig.setUiForm( mEditFormLineEdit->text(), errMsg ) )
+    QgisApp::instance()->messageBar()->pushMessage( *errMsg, Qgis::Warning );
 
   editFormConfig.setLayout( ( QgsEditFormConfig::EditorLayout ) mEditorLayoutComboBox->currentIndex() );
 

src/core/qgseditformconfig.cpp

@@ -14,6 +14,7 @@
  ***************************************************************************/
 #include "qgseditformconfig_p.h"
 #include "qgseditformconfig.h"
+#include "qgsnetworkcontentfetcher.h"
 #include "qgspathresolver.h"
 #include "qgsproject.h"
 #include "qgsreadwritecontext.h"
@@ -146,22 +147,75 @@ void QgsEditFormConfig::setLayout( QgsEditFormConfig::EditorLayout editorLayout
     d->mConfiguredRootContainer = true;
 }
 
-QString QgsEditFormConfig::uiForm() const
+QString QgsEditFormConfig::uiForm( FormPath path ) const
 {
-  return d->mUiFormPath;
+  if ( path == Original && !d->mUiFormUrl.isEmpty() )
+    return d->mUiFormUrl;
+  else
+    return d->mUiFormPath;
 }
 
-void QgsEditFormConfig::setUiForm( const QString &ui )
+bool QgsEditFormConfig::setUiForm( const QString &ui, QString *errMsg )
 {
-  if ( ui.isEmpty() || ui.isNull() )
+  bool success = false;
+
+  if ( !ui.isEmpty() && ui == d->mUiFormUrl && !d->mUiFormPath.isEmpty() )
+  {
+    // do not download again if URL did not change and was correctly loaded before
+    return success;
+  }
+
+  // if the ui points to a URL make a local copy
+  QString formPath = ui;
+  QString formUrl = QString();
+  if ( !ui.isEmpty() && !QUrl::fromUserInput( ui ).isLocalFile() )
+  {
+    formPath = QString();
+    formUrl = ui;
+
+    QgsNetworkContentFetcher fetcher;
+    QEventLoop loop;
+    QObject::connect( &fetcher, &QgsNetworkContentFetcher::finished, &loop, &QEventLoop::quit );
+    fetcher.fetchContent( QUrl( ui ) );
+
+    //wait until form is fetched
+    loop.exec( QEventLoop::ExcludeUserInputEvents );
+
+    QNetworkReply *reply = fetcher.reply();
+    if ( reply )
+    {
+      QTemporaryFile *localFile = new QTemporaryFile( QStringLiteral( "XXXXXX.ui" ) );
+      if ( localFile->open() )
+      {
+        localFile->write( reply->readAll() );
+        localFile->close();
+        success = true;
+        QgsProject::instance()->addUiFormLocalCopy( localFile );
+        formPath = localFile->fileName();
+      }
+    }
+    if ( !success && errMsg )
+    {
+      *errMsg = QString( "Could not load UI from %1" ).arg( ui );
+    }
+  }
+  else
+  {
+    success = true;
+  }
+
+  if ( formPath.isEmpty() )
   {
     setLayout( GeneratedLayout );
   }
   else
   {
     setLayout( UiFileLayout );
   }
-  d->mUiFormPath = ui;
+  d->mUiFormPath = formPath;
+  d->mUiFormUrl = formUrl;
+
+  return success;
 }
 
 bool QgsEditFormConfig::readOnly( int idx ) const
@@ -268,7 +322,9 @@ void QgsEditFormConfig::readXml( const QDomNode &node, QgsReadWriteContext &cont
   if ( !editFormNode.isNull() )
   {
     QDomElement e = editFormNode.toElement();
-    d->mUiFormPath = context.pathResolver().readPath( e.text() );
+    QString *errMsg = new QString();
+    if ( !setUiForm( context.pathResolver().readPath( e.text() ), errMsg ) )
+      context.pushMessage( *errMsg, Qgis::Warning );
   }
 
   QDomNode editFormInitNode = node.namedItem( QStringLiteral( "editforminit" ) );
@@ -396,7 +452,7 @@ void QgsEditFormConfig::writeXml( QDomNode &node, const QgsReadWriteContext &con
   QDomDocument doc( node.ownerDocument() );
 
   QDomElement efField  = doc.createElement( QStringLiteral( "editform" ) );
-  QDomText efText = doc.createTextNode( context.pathResolver().writePath( uiForm() ) );
+  QDomText efText = doc.createTextNode( context.pathResolver().writePath( uiForm( Original ) ) );
   efField.appendChild( efText );
   node.appendChild( efField );
 

src/core/qgseditformconfig.h

@@ -25,8 +25,8 @@
 #include <QDomDocument>
 
 #include "qgsattributeeditorelement.h"
+#include "qgsreadwritecontext.h"
 
-class QgsReadWriteContext;
 class QgsRelationManager;
 class QgsEditFormConfigPrivate;
 
@@ -93,6 +93,15 @@ class CORE_EXPORT QgsEditFormConfig
       CodeSourceEnvironment = 3       //!< Use the Python code available in the Python environment
     };
 
+    /**
+     * The FormPath enum determins the path of the custom UI form
+     */
+    enum FormPath
+    {
+      Original, //!< User entered directory or URL
+      LocalCopy //!< If the Original is an URL, this is for the local copy of the file
+    };
+
     /**
      * Copy constructor
      *
@@ -135,16 +144,22 @@ class CORE_EXPORT QgsEditFormConfig
     //! Set the active layout style for the attribute editor for this layer
     void setLayout( EditorLayout editorLayout );
 
-    //! Get path to the .ui form. Only meaningful with EditorLayout::UiFileLayout.
-    QString uiForm() const;
+    /**
+     * \brief Get path to the .ui form. Only meaningful with EditorLayout::UiFileLayout
+     * If the form is from a URL and \a path is Original, the original URL
+     * of the UI form is returned instead of the local copy.
+     */
+    QString uiForm( FormPath path = LocalCopy ) const;
 
     /**
      * Set path to the .ui form.
-     * When a string is provided, the layout style will be set to EditorLayout::UiFileLayout,
+     * When a string is provided in \a ui, the layout style will be set to EditorLayout::UiFileLayout,
      * if an empty or a null string is provided, the layout style will be set to
      * EditorLayout::GeneratedLayout.
+     * If \a ui is a URL, a local copy of the file will be made and will be used to create the forms
+     * \a context is provided to save error messages
      */
-    void setUiForm( const QString &ui );
+    bool setUiForm( const QString &ui, QString *errMsg SIP_OUT = nullptr );
 
     /**
      * Set the editor widget config for a widget which is not for a simple field.

src/core/qgseditformconfig_p.h

@@ -65,8 +65,10 @@ class QgsEditFormConfigPrivate : public QSharedData
     //! Defines the default layout to use for the attribute editor (Drag and drop, UI File, Generated)
     QgsEditFormConfig::EditorLayout mEditorLayout = QgsEditFormConfig::GeneratedLayout;
 
-    //! Init form instance
+    //! Path to the UI form
     QString mUiFormPath;
+    //! URL of the UI form if taken from the web
+    QString mUiFormUrl;
     //! Name of the Python form init function
     QString mInitFunction;
     //! Path of the Python external file to be loaded

src/core/qgsproject.cpp

@@ -2687,3 +2687,8 @@ void QgsProject::setRequiredLayers( const QSet<QgsMapLayer *> &layers )
   }
   writeEntry( QStringLiteral( "RequiredLayers" ), QStringLiteral( "Layers" ), layerIds );
 }
+
+void QgsProject::addUiFormLocalCopy( QTemporaryFile *file )
+{
+  mUiFormLocalCopies.append( file );
+}

src/core/qgsproject.h

@@ -1351,6 +1351,9 @@ class CORE_EXPORT QgsProject : public QObject, public QgsExpressionContextGenera
 
     QgsCoordinateTransformContext mTransformContext;
 
+    // local temporary copies of downloaded UI form files
+    QList<QPointer<QTemporaryFile>> mUiFormLocalCopies;
+
     QgsProjectMetadata mMetadata;
 
     friend class QgsProjectDirtyBlocker;

src/gui/qgsattributeform.cpp

@@ -1117,23 +1117,27 @@ void QgsAttributeForm::init()
   if ( mContext.allowCustomUi() && mLayer->editFormConfig().layout() == QgsEditFormConfig::UiFileLayout &&
        !mLayer->editFormConfig().uiForm().isEmpty() )
   {
-    QFile file( mLayer->editFormConfig().uiForm() );
+    QgsDebugMsg( QString( "loading form: %1" ).arg( mLayer->editFormConfig().uiForm() ) );
+    QFile file( mLayer->editFormConfig().uiForm( QgsEditFormConfig::LocalCopy ) );
 
     if ( file.open( QFile::ReadOnly ) )
     {
       QUiLoader loader;
 
-      QFileInfo fi( mLayer->editFormConfig().uiForm() );
+      QFileInfo fi( file );
       loader.setWorkingDirectory( fi.dir() );
       formWidget = loader.load( &file, this );
-      formWidget->setWindowFlags( Qt::Widget );
-      layout->addWidget( formWidget );
-      formWidget->show();
-      file.close();
-      mButtonBox = findChild<QDialogButtonBox *>();
-      createWrappers();
-
-      formWidget->installEventFilter( this );
+      if ( formWidget )
+      {
+        formWidget->setWindowFlags( Qt::Widget );
+        layout->addWidget( formWidget );
+        formWidget->show();
+        file.close();
+        mButtonBox = findChild<QDialogButtonBox *>();
+        createWrappers();
+
+        formWidget->installEventFilter( this );
+      }
     }
   }