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[feature] array_foreach expression function - add counter variable #54962

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merged 3 commits into from
Oct 29, 2023
Merged

[feature] array_foreach expression function - add counter variable #54962

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bd40d71
array_foreach expression - add counter variable
pathmapper Oct 17, 2023
38be39e
Add note that counter starts at 0
pathmapper Oct 17, 2023
c1c7633
Update resources/function_help/json/array_foreach
nyalldawson Oct 28, 2023
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5 changes: 4 additions & 1 deletion resources/function_help/json/array_foreach
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Original file line number Diff line number Diff line change
Expand Up @@ -8,14 +8,17 @@
"description": "an array"
}, {
"arg": "expression",
"description": "an expression to evaluate on each item. The variable `@element` will be replaced by the current value."
"description": "an expression to evaluate on each item. The variable `@element` will be replaced by the current value and the variable `@counter` by the current index (starting with 0)."
}],
"examples": [{
"expression": "array_foreach(array('a','b','c'),upper(@element))",
"returns": "[ 'A', 'B', 'C' ]"
}, {
"expression": "array_foreach(array(1,2,3),@element + 10)",
"returns": "[ 11, 12, 13 ]"
}, {
"expression": "array_foreach(array(1,2,3),@element + @counter)",
"returns": "[ 1, 3, 5 ]"
}],
"tags": ["evaluated", "array", "iterate", "item"]
}
5 changes: 4 additions & 1 deletion src/core/expression/qgsexpressionfunction.cpp
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Expand Up @@ -9353,9 +9353,11 @@ QVariant QgsArrayForeachExpressionFunction::run( QgsExpressionNode::NodeList *ar
QgsExpressionContextScope *subScope = new QgsExpressionContextScope();
subContext->appendScope( subScope );

for ( QVariantList::const_iterator it = array.constBegin(); it != array.constEnd(); ++it )
int i = 0;
for ( QVariantList::const_iterator it = array.constBegin(); it != array.constEnd(); ++it, ++i )
{
subScope->addVariable( QgsExpressionContextScope::StaticVariable( QStringLiteral( "element" ), *it, true ) );
subScope->addVariable( QgsExpressionContextScope::StaticVariable( QStringLiteral( "counter" ), i, true ) );
result << args->at( 1 )->eval( parent, subContext );
}

Expand Down Expand Up @@ -9393,6 +9395,7 @@ bool QgsArrayForeachExpressionFunction::prepare( const QgsExpressionNodeFunction

QgsExpressionContextScope *subScope = new QgsExpressionContextScope();
subScope->addVariable( QgsExpressionContextScope::StaticVariable( QStringLiteral( "element" ), QVariant(), true ) );
subScope->addVariable( QgsExpressionContextScope::StaticVariable( QStringLiteral( "counter" ), QVariant(), true ) );
subContext.appendScope( subScope );

args->at( 1 )->prepare( parent, &subContext );
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1 change: 1 addition & 0 deletions tests/src/core/testqgsexpression.cpp
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Expand Up @@ -4340,6 +4340,7 @@ class TestQgsExpression: public QObject
QVariantList foreachExpected;
foreachExpected << 10 << 20 << 40;
QCOMPARE( QgsExpression( "array_foreach(array(1, 2, 4), @element * 10)" ).evaluate( &context ), QVariant( foreachExpected ) );
QCOMPARE( QgsExpression( "array_foreach(array(10, 19, 38), @element + @counter)" ).evaluate( &context ), QVariant( foreachExpected ) );

QVariantList filterExpected = QVariantList() << 1 << 2;
QCOMPARE( QgsExpression( "array_filter(array(1, 2, 4), @element < 3)" ).evaluate( &context ), QVariant( filterExpected ) );
Expand Down