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Unwrap optionals with safe navigation in expressions #9024

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Mar 30, 2023
Merged

Unwrap optionals with safe navigation in expressions #9024

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37 changes: 27 additions & 10 deletions ...processor/src/main/java/io/micronaut/expressions/parser/ast/access/ElementMethodCall.java
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Original file line number Diff line number Diff line change
Expand Up @@ -16,22 +16,23 @@
package io.micronaut.expressions.parser.ast.access;

import io.micronaut.core.annotation.Internal;
import io.micronaut.core.reflect.ReflectionUtils;
import io.micronaut.expressions.parser.ast.ExpressionNode;
import io.micronaut.expressions.parser.ast.types.TypeIdentifier;
import io.micronaut.expressions.parser.compilation.ExpressionVisitorContext;
import io.micronaut.expressions.parser.exception.ExpressionCompilationException;
import io.micronaut.inject.ast.ClassElement;
import io.micronaut.inject.ast.ElementQuery;
import io.micronaut.inject.ast.MethodElement;
import io.micronaut.inject.visitor.VisitorContext;
import io.micronaut.inject.processing.JavaModelUtils;
import org.objectweb.asm.Label;
import org.objectweb.asm.Type;
import org.objectweb.asm.commons.GeneratorAdapter;
import org.objectweb.asm.commons.Method;

import java.util.List;
import java.util.Optional;

import static io.micronaut.expressions.parser.ast.util.EvaluatedExpressionCompilationUtils.getRequiredClassElement;
import static org.objectweb.asm.Opcodes.ACONST_NULL;
import static org.objectweb.asm.Opcodes.INVOKESTATIC;

Expand All @@ -46,6 +47,8 @@
@Internal
public sealed class ElementMethodCall extends AbstractMethodCall permits PropertyAccess {

private static final Type TYPE_OPTIONAL = Type.getType(Optional.class);
private static final Method METHOD_OR_ELSE = Method.getMethod(ReflectionUtils.getRequiredInternalMethod(Optional.class, "orElse", Object.class));
protected final ExpressionNode callee;
private final boolean nullSafe;

Expand All @@ -58,14 +61,19 @@ public ElementMethodCall(ExpressionNode callee,
this.nullSafe = nullSafe;
}

/**
* @return Is the method call null safe
*/
protected boolean isNullSafe() {
return nullSafe;
}

@Override
protected void generateBytecode(ExpressionVisitorContext ctx) {
GeneratorAdapter mv = ctx.methodVisitor();
VisitorContext visitorContext = ctx.visitorContext();
Type calleeType = callee.resolveType(ctx);
ClassElement calleeClass = callee.resolveClassElement(ctx);
Method method = usedMethod.toAsmMethod();

ClassElement calleeClass = getRequiredClassElement(calleeType, visitorContext);
Type calleeType = JavaModelUtils.getTypeReference(calleeClass);

if (callee instanceof TypeIdentifier) {
compileArguments(ctx);
Expand All @@ -78,16 +86,25 @@ protected void generateBytecode(ExpressionVisitorContext ctx) {
} else {
callee.compile(ctx);
if (nullSafe) {
if (calleeClass.isAssignable(Optional.class)) {
mv.checkCast(TYPE_OPTIONAL);
// safe navigate optional
mv.visitInsn(ACONST_NULL);
mv.invokeVirtual(TYPE_OPTIONAL, METHOD_OR_ELSE);
// recompute new return type
calleeClass = calleeClass.getFirstTypeArgument().orElse(ClassElement.of(Object.class));
calleeType = JavaModelUtils.getTypeReference(calleeClass);
mv.checkCast(calleeType);
}
// null safe operator is used so we need to check the result is null
Type returnType = method.getReturnType();
mv.storeLocal(2, returnType);
mv.loadLocal(2, returnType);
mv.storeLocal(2, calleeType);
mv.loadLocal(2, calleeType);
Label proceed = new Label();
mv.ifNonNull(proceed);
mv.visitInsn(ACONST_NULL);
mv.returnValue();
mv.visitLabel(proceed);
mv.loadLocal(2, returnType);
mv.loadLocal(2, calleeType);
}
compileArguments(ctx);
if (calleeClass.isInterface()) {
Expand Down
21 changes: 13 additions & 8 deletions core-processor/src/main/java/io/micronaut/expressions/parser/ast/access/PropertyAccess.java
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Expand Up @@ -23,12 +23,11 @@
import io.micronaut.inject.ast.MethodElement;
import io.micronaut.inject.ast.PropertyElement;
import io.micronaut.inject.ast.PropertyElementQuery;
import org.objectweb.asm.Type;

import java.util.Collections;
import java.util.List;
import java.util.Optional;

import static io.micronaut.expressions.parser.ast.util.EvaluatedExpressionCompilationUtils.getRequiredClassElement;
import static java.util.Collections.emptyList;
import static java.util.function.Predicate.not;

Expand All @@ -48,30 +47,36 @@ public PropertyAccess(ExpressionNode callee, String name, boolean nullSafe) {

@Override
protected CandidateMethod resolveUsedMethod(ExpressionVisitorContext ctx) {
Type calleeType = callee.resolveType(ctx);
ClassElement classElement = getRequiredClassElement(calleeType, ctx.visitorContext());
ClassElement classElement = callee.resolveClassElement(ctx);

if (isNullSafe() && classElement.isAssignable(Optional.class)) {
// safe navigate optional
classElement = classElement.getFirstTypeArgument().orElse(classElement);
}

List<PropertyElement> propertyElements =
classElement.getBeanProperties(
PropertyElementQuery.of(classElement.getAnnotationMetadata())
.allowStaticProperties(false)
.includes(Collections.singleton(name))).stream()
.filter(not(PropertyElement::isExcluded))
.toList();

if (propertyElements.size() == 0) {
if (propertyElements.isEmpty()) {
throw new ExpressionCompilationException(
"Can not find property with name [" + name + "] in class " + calleeType);
"Can not find property with name [" + name + "] in class " + classElement.getName());
} else if (propertyElements.size() > 1) {
throw new ExpressionCompilationException(
"Ambiguous property access. Found " + propertyElements.size() +
" matching properties with name [" + name + "] in class " + calleeType);
" matching properties with name [" + name + "] in class " + classElement.getName());
}

PropertyElement property = propertyElements.iterator().next();
ClassElement finalClassElement = classElement;
MethodElement methodElement =
property.getReadMethod()
.orElseThrow(() -> new ExpressionCompilationException(
"Can not resolve access method for property [" + name + "] in class " + calleeType));
"Can not resolve access method for property [" + name + "] in class " + finalClassElement.getName()));

return new CandidateMethod(methodElement);
}
Expand Down
95 changes: 95 additions & 0 deletions ...java/src/test/groovy/io/micronaut/expressions/ContextPropertyAccessExpressionsSpec.groovy
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Expand Up @@ -142,6 +142,101 @@ class ContextPropertyAccessExpressionsSpec extends AbstractEvaluatedExpressionsS
expr == null
}

void "test multi-level context property access safe navigation - success"() {
given:
Object expr = evaluateAgainstContext("#{ foo?.bar?.name }",
"""
@jakarta.inject.Singleton
class Context {
public Foo getFoo() {
return new Foo();
}
}

class Foo {
private Bar bar = new Bar();
public Bar getBar() {
return bar;
}
}

class Bar {
private String name = "test";
public String getName() {
return name;
}
}
""")

expect:
expr == "test"
}

void "test multi-level context property access safe navigation with optionals"() {
given:
Object expr = evaluateAgainstContext("#{ foo?.bar?.name }",
"""
import java.util.Optional;

@jakarta.inject.Singleton
class Context {
public Optional<Foo> getFoo() {
return Optional.of(new Foo());
}
}

class Foo {
private Bar bar;
public Optional<Bar> getBar() {
return Optional.ofNullable(bar);
}
}

class Bar {
private String name = "test";
public String getName() {
return name;
}
}
""")

expect:
expr == null
}

void "test multi-level context property access safe navigation with optionals - success"() {
given:
Object expr = evaluateAgainstContext("#{ foo?.bar?.name }",
"""
import java.util.Optional;

@jakarta.inject.Singleton
class Context {
public Optional<Foo> getFoo() {
return Optional.of(new Foo());
}
}

class Foo {
private Bar bar = new Bar();
public Optional<Bar> getBar() {
return Optional.ofNullable(bar);
}
}

class Bar {
private String name = "test";
public String getName() {
return name;
}
}
""")

expect:
expr == "test"
}


void "test multi-level context property access non-safe navigation"() {
when:
Object expr = evaluateAgainstContext("#{ foo.bar.name }",
Expand Down
2 changes: 2 additions & 0 deletions src/main/docs/guide/config/evaluatedExpressions.adoc
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Expand Up @@ -210,6 +210,8 @@ You can also use the safe dereference operator `?.` to navigate paths in a null
#{ foo?.bar?.name == "Fred" }
----

TIP: When used, the safe dereference operator will also automatically unwrap Java's `Optional` type.

=== Type References

A predefined syntax construct `T(...)` can be used to reference a class. The value inside brackets should be fully
Expand Down