Support $count on navigation properties in $filter (#871)

src/Drivers/MongoEntitySet.php

@@ -419,6 +419,10 @@ protected function evaluateFilter(?Node $node)
             case $node instanceof Node\Literal:
                 return $node->getValue()->get();
 
+            case $node instanceof Node\Property\Navigation\Count:
+                $node->notImplemented();
+
+            // no break
             case $node instanceof Node\Property:
                 return '$'.$node->getValue()->getName();
         }

src/Drivers/SQL/SQLExpression.php

@@ -103,6 +103,10 @@ public function evaluate(Node $node): void
                 $this->lambdaExpression($node);
                 break;
 
+            case $node instanceof Node\Property\Navigation\Count:
+                $this->navigationPropertyCountExpression($node);
+                break;
+
             case $node instanceof Property:
                 $this->propertyExpression($node);
                 break;
@@ -1289,6 +1293,56 @@ protected function literalExpression(Literal $node): void
      * @param  Lambda  $node  Node
      * @return void
      */
+    /**
+     * Expand a navigation property count expression into a correlated COUNT subquery
+     * @param  Node\Property\Navigation\Count  $node  Node
+     * @return void
+     */
+    protected function navigationPropertyCountExpression(Node\Property\Navigation\Count $node): void
+    {
+        /** @var NavigationProperty $navigationProperty */
+        $navigationProperty = $node->getValue();
+
+        /** @var NavigationBinding $navigationBinding */
+        $navigationBinding = $this->entitySet->getBindingByNavigationProperty($navigationProperty);
+
+        /** @var SQLEntitySet $targetSet */
+        $targetSet = $navigationBinding->getTarget();
+
+        /** @var ReferentialConstraint[] $constraints */
+        $constraints = $navigationBinding->getPath()->getConstraints()->all();
+
+        if (!$constraints) {
+            $node->notImplemented();
+        }
+
+        $this->pushStatement(
+            sprintf(
+                '( SELECT COUNT(*) FROM %s WHERE',
+                $targetSet->quoteSingleIdentifier($targetSet->getTable())
+            )
+        );
+
+        $first = true;
+
+        foreach ($constraints as $constraint) {
+            if (!$first) {
+                $this->pushStatement('AND');
+            }
+
+            $first = false;
+
+            $referencedField = $targetSet->propertyToExpression($constraint->getReferencedProperty());
+            $localField = $this->entitySet->propertyToExpression($constraint->getProperty());
+
+            $this->pushStatement(sprintf('%s = %s', $referencedField->getStatement(), $localField->getStatement()));
+            $this->pushParameters($referencedField->getParameters());
+            $this->pushParameters($localField->getParameters());
+        }
+
+        $this->pushStatement(')');
+    }
+
     protected function lambdaExpression(Lambda $node): void
     {
         $driver = $this->entitySet->getDriver();

src/Expression/Node/Property/Navigation/Count.php

@@ -0,0 +1,19 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Flat3\Lodata\Expression\Node\Property\Navigation;
+
+use Flat3\Lodata\Expression\Node\Property\Navigation;
+
+/**
+ * Navigation property count
+ *
+ * Represents `$count` applied to a collection-valued navigation property within an
+ * expression, for example `passengers/$count` in a `$filter`. The node carries the
+ * navigation property it counts and is evaluated to the number of related entities.
+ * @package Flat3\Lodata\Expression\Node\Property\Navigation
+ */
+class Count extends Navigation
+{
+}

src/Expression/Parser.php

@@ -616,6 +616,42 @@ public function tokenizeTimeOfDay(): bool
         return true;
     }
 
+    /**
+     * Tokenize a navigation property count (e.g. `passengers/$count`)
+     * @return bool
+     */
+    public function tokenizeNavigationPropertyCount(): bool
+    {
+        $currentResource = $this->getCurrentResource();
+
+        if (!$currentResource) {
+            return false;
+        }
+
+        $navigationProperties = $currentResource->getType()->getNavigationProperties();
+
+        $token = $this->lexer->with(function () use ($navigationProperties) {
+            $identifier = $this->lexer->identifier();
+            $this->lexer->char(Lexer::pathSeparator);
+            $this->lexer->literal('$count');
+
+            return $navigationProperties->get($identifier) ? $identifier : null;
+        });
+
+        if (!$token) {
+            return false;
+        }
+
+        $property = $navigationProperties->get($token);
+
+        $operand = new Node\Property\Navigation\Count($this);
+        $operand->setValue($property);
+        $this->operandStack[] = $operand;
+        $this->tokens[] = $operand;
+
+        return true;
+    }
+
     /**
      * Tokenize a navigation property path
      * @return bool

src/Expression/Parser/Common.php

@@ -85,6 +85,12 @@ public static function evaluate(Node $node, ?Entity $entity = null): ?Primitive
         }
 
         switch (true) {
+            case $node instanceof Node\Property\Navigation\Count:
+                throw new NotImplementedException(
+                    'unsupported_expression',
+                    'This entity set does not support counting a navigation property within an expression'
+                );
+
             // Deserialization
             case $node instanceof Node\Property:
                 $propertyValue = $entity[$node->getValue()];

src/Expression/Parser/Filter.php

@@ -113,6 +113,7 @@ protected function findToken(): bool
             $this->tokenizeDeclaredProperty() ||
             $this->tokenizeComputedProperty() ||
             $this->tokenizeOperator() ||
+            $this->tokenizeNavigationPropertyCount() ||
             $this->tokenizeNavigationPropertyPath();
     }
 

tests/Filter/Database.php

@@ -94,4 +94,31 @@ public function test_filter_all()
                 ->expand('MyPets')
         );
     }
+
+    public function test_filter_navigation_count_eq()
+    {
+        $this->assertJsonResponseSnapshot(
+            (new Request)
+                ->path($this->entitySet)
+                ->filter('MyPets/$count eq 0')
+        );
+    }
+
+    public function test_filter_navigation_count_gt()
+    {
+        $this->assertJsonResponseSnapshot(
+            (new Request)
+                ->path($this->entitySet)
+                ->filter('MyPets/$count gt 1')
+        );
+    }
+
+    public function test_filter_navigation_count_combined()
+    {
+        $this->assertJsonResponseSnapshot(
+            (new Request)
+                ->path($this->entitySet)
+                ->filter('MyPets/$count gt 1 or id eq 2')
+        );
+    }
 }

tests/Filter/MongoTest.php

@@ -29,4 +29,19 @@ public function test_path_query_filter_search()
     {
         $this->markTestSkipped();
     }
+
+    public function test_filter_navigation_count_eq()
+    {
+        $this->markTestSkipped();
+    }
+
+    public function test_filter_navigation_count_gt()
+    {
+        $this->markTestSkipped();
+    }
+
+    public function test_filter_navigation_count_combined()
+    {
+        $this->markTestSkipped();
+    }
 }

tests/Parser/Handlers/LoopbackEntitySet.php

@@ -170,6 +170,10 @@ public function commonExpression(Node $node): void
                 ));
                 return;
 
+            case $node instanceof Node\Property\Navigation\Count:
+                $this->addCommon(sprintf('%s/$count', $node->getValue()));
+                return;
+
             case $node instanceof Node\Property:
                 $this->addCommon($node->getValue());
                 return;

tests/Parser/LambdaTest.php

@@ -28,4 +28,19 @@ public function test_5g()
     {
         $this->assertLambda("airports/any(d:d/name eq 'hello') and 1 eq 2 or airports/all(d:d/name eq 'hello')");
     }
+
+    public function test_count_single_constraint()
+    {
+        $this->assertLambda('da/$count eq 1');
+    }
+
+    public function test_count_multiple_constraints()
+    {
+        $this->assertLambda('airports/$count gt 0');
+    }
+
+    public function test_count_logical_combination()
+    {
+        $this->assertLambda('da/$count ge 2 or airports/$count eq 0');
+    }
 }

tests/__snapshots__/Filter/EloquentTest__test_filter_navigation_count_combined__1.json

@@ -0,0 +1,52 @@
+{
+    "@context": "http://localhost/odata/$metadata#Passengers",
+    "value": [
+        {
+            "id": 1,
+            "flight_id": 1,
+            "name": "Alpha",
+            "dob": "2000-01-01T04:04:04+00:00",
+            "age": 4,
+            "chips": true,
+            "dq": "2000-01-01",
+            "in_role": "P1DT0S",
+            "open_time": "05:05:05.000000",
+            "colour": "Green",
+            "sock_colours": "Green,Blue",
+            "emails": [
+                "alpha@example.com",
+                "alpha@beta.com"
+            ]
+        },
+        {
+            "id": 2,
+            "flight_id": null,
+            "name": "Beta",
+            "dob": "2001-02-02T05:05:05+00:00",
+            "age": 3,
+            "chips": false,
+            "dq": "2001-02-02",
+            "in_role": "P2DT5H5M5.2999999999884S",
+            "open_time": null,
+            "colour": null,
+            "sock_colours": null,
+            "emails": []
+        },
+        {
+            "id": 3,
+            "flight_id": 1,
+            "name": "Gamma",
+            "dob": "2002-03-03T06:06:06+00:00",
+            "age": 2,
+            "chips": true,
+            "dq": "2002-03-03",
+            "in_role": "P4DT32M41S",
+            "open_time": "07:07:07.000000",
+            "colour": "Blue",
+            "sock_colours": "Red,Green,Blue",
+            "emails": [
+                "gamma@example.com"
+            ]
+        }
+    ]
+}

tests/__snapshots__/Filter/EloquentTest__test_filter_navigation_count_eq__1.json

@@ -0,0 +1,47 @@
+{
+    "@context": "http://localhost/odata/$metadata#Passengers",
+    "value": [
+        {
+            "id": 2,
+            "flight_id": null,
+            "name": "Beta",
+            "dob": "2001-02-02T05:05:05+00:00",
+            "age": 3,
+            "chips": false,
+            "dq": "2001-02-02",
+            "in_role": "P2DT5H5M5.2999999999884S",
+            "open_time": null,
+            "colour": null,
+            "sock_colours": null,
+            "emails": []
+        },
+        {
+            "id": 4,
+            "flight_id": null,
+            "name": "Delta",
+            "dob": null,
+            "age": null,
+            "chips": null,
+            "dq": null,
+            "in_role": "PT2M7S",
+            "open_time": null,
+            "colour": null,
+            "sock_colours": null,
+            "emails": []
+        },
+        {
+            "id": 5,
+            "flight_id": null,
+            "name": "Epsilon",
+            "dob": "2003-04-04T07:07:07+00:00",
+            "age": 2.4,
+            "chips": null,
+            "dq": "2003-04-04",
+            "in_role": "PT14M48.9S",
+            "open_time": "23:11:33.000000",
+            "colour": null,
+            "sock_colours": null,
+            "emails": []
+        }
+    ]
+}

tests/__snapshots__/Filter/EloquentTest__test_filter_navigation_count_gt__1.json

@@ -0,0 +1,38 @@
+{
+    "@context": "http://localhost/odata/$metadata#Passengers",
+    "value": [
+        {
+            "id": 1,
+            "flight_id": 1,
+            "name": "Alpha",
+            "dob": "2000-01-01T04:04:04+00:00",
+            "age": 4,
+            "chips": true,
+            "dq": "2000-01-01",
+            "in_role": "P1DT0S",
+            "open_time": "05:05:05.000000",
+            "colour": "Green",
+            "sock_colours": "Green,Blue",
+            "emails": [
+                "alpha@example.com",
+                "alpha@beta.com"
+            ]
+        },
+        {
+            "id": 3,
+            "flight_id": 1,
+            "name": "Gamma",
+            "dob": "2002-03-03T06:06:06+00:00",
+            "age": 2,
+            "chips": true,
+            "dq": "2002-03-03",
+            "in_role": "P4DT32M41S",
+            "open_time": "07:07:07.000000",
+            "colour": "Blue",
+            "sock_colours": "Red,Green,Blue",
+            "emails": [
+                "gamma@example.com"
+            ]
+        }
+    ]
+}