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Merge pull request #39921 from roya0045/negative_array_Get

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[Feature][Expression]Negative array get
This commit is contained in:
Matthias Kuhn 2020-11-17 08:46:20 +01:00 committed by GitHub
commit aeb9463b47
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3 changed files with 14 additions and 6 deletions
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7
resources/function_help/json/array_get
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@ -2,8 +2,11 @@
"name": "array_get",
"type": "function",
"groups": ["Arrays"],
"description": "Returns the Nth value (0 for the first one) of an array.",
"description": "Returns the Nth value (0 for the first one) or the last -Nth value (-1 for the last one) of an array.",
"arguments": [ {"arg":"array","description":"an array"},
{"arg":"index","description":"the index to get (0 based)"}],
"examples": [ { "expression":"array_get(array('a','b','c'),1)", "returns":"'b'"}]
"examples": [
{ "expression":"array_get(array('a','b','c'),1)", "returns":"'b'"},
{ "expression":"array_get(array('a','b','c'),-1)", "returns":"'c'"}
]
}

6
src/core/expression/qgsexpressionfunction.cpp
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@ -5324,8 +5324,10 @@ static QVariant fcnArrayGet( const QVariantList &values, const QgsExpressionCont
{
const QVariantList list = QgsExpressionUtils::getListValue( values.at( 0 ), parent );
const int pos = QgsExpressionUtils::getNativeIntValue( values.at( 1 ), parent );
if ( pos < 0 || pos >= list.length() ) return QVariant();
return list.at( pos );
if ( pos < list.length() && pos >= 0 ) return list.at( pos );
else if ( pos < 0 && ( list.length() + pos ) >= 0 )
return list.at( list.length() + pos );
return QVariant();
}
static QVariant fcnArrayFirst( const QVariantList &values, const QgsExpressionContext *, QgsExpression *parent, const QgsExpressionNodeFunction * )

7
tests/src/core/testqgsexpression.cpp
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@ -3333,7 +3333,8 @@ class TestQgsExpression: public QObject
QCOMPARE( QgsExpression( "array_get(\"strings\", 1)" ).evaluate( &context ), QVariant( "two" ) );
QCOMPARE( QgsExpression( "array_get(\"strings\", 2)" ).evaluate( &context ), QVariant() );
QCOMPARE( QgsExpression( "array_get(\"strings\", -1)" ).evaluate( &context ), QVariant() );
QCOMPARE( QgsExpression( "array_get(\"strings\", -1)" ).evaluate( &context ), QVariant( "two" ) );
QCOMPARE( QgsExpression( "array_get(\"strings\", -4)" ).evaluate( &context ), QVariant() );
QStringList appendExpected = array;
appendExpected << QStringLiteral( "three" );
@ -3409,7 +3410,9 @@ class TestQgsExpression: public QObject
QCOMPARE( QgsExpression( "array_get(\"ints\", 1)" ).evaluate( &context ), QVariant( -2 ) );
QCOMPARE( QgsExpression( "array_get(\"ints\", 2)" ).evaluate( &context ), QVariant() );
QCOMPARE( QgsExpression( "array_get(\"ints\", -1)" ).evaluate( &context ), QVariant() );
QCOMPARE( QgsExpression( "array_get(\"ints\", -1)" ).evaluate( &context ), QVariant( -2 ) );
QCOMPARE( QgsExpression( "array_get(\"ints\", -2)" ).evaluate( &context ), QVariant( 1 ) );
QCOMPARE( QgsExpression( "array_get(\"ints\", -3)" ).evaluate( &context ), QVariant() );
QVariantList appendExpected = array;
appendExpected << 3;