Support custom aliases for aggregations

Author: nealarec

src/SQLProviders/SQLFunctions.php

@@ -21,10 +21,19 @@ class SQLFunctions
 
     final public static function validateArgument(string $argument): void
     {
+        $columnRegex = "/^(((_*)?([A-Za-z0-9]+))+|\*)$/";
+        if(strpos($argument, " as ")) {
+            [$argument, $alias] = explode(" as ", $argument);
+            if(!preg_match($columnRegex, $alias)) {
+                throw new JsonQueryBuilderException(
+                    "Invalid alias name: {$alias}."
+                ); 
+            }
+        }
+
         $split = explode(':', $argument);
         $column = array_pop($split);
-
-        if (!preg_match("/^[a-zA-Z_][a-zA-Z0-9_]*|\*$/", $column) || in_array($column, self::DB_FUNCTIONS)) {
+        if (!preg_match($columnRegex, $column) || in_array($column, self::DB_FUNCTIONS)) {
             throw new JsonQueryBuilderException(
                 "Invalid column name: {$column}."
             );

src/Traits/DatabaseFunctions.php

@@ -10,6 +10,7 @@
 trait DatabaseFunctions
 {
     public Builder $builder;
+    public $alias;
 
     protected array $providers = [
         'pgsql' => PgSQLFunctions::class,
@@ -28,13 +29,15 @@ private function applyAggregation(array $params): string
         $column = array_pop($params);
         $provider = $this->builder->getModel()->connection ?? config('database.default');
         $functions = $this->providers[$provider] ?? SQLFunctions::class;
+        if (strpos($column, " as ")) {
+            [$column, $this->alias] = explode(" as ", $column);
+        }
 
         return array_reduce(array_reverse($params), function ($query, $param) use (
             $column,
             $functions
         ) {
             $stat = $query ?? ('*' !== $column ? "\"$column\"" : $column);
-
             return $functions::$param($stat);
         });
     }
@@ -47,8 +50,9 @@ protected function prepareArguments(): void
             }
             $split = explode(':', $argument);
             $apply = $this->applyAggregation($split);
-            $alias = join('_', array_filter($split, fn ($s) => '*' !== $s));
 
+            if(last($split) === '*') array_pop($split);
+            $alias = $this->alias ?? join('_', $split);
             return DB::raw("{$apply} as {$alias}");
         }, $this->arguments);
     }

tests/Unit/SQLProviders/SQLFunctionsTest.php

@@ -1,6 +1,6 @@
 <?php
 
-declare(strict_types=1);
+declare (strict_types = 1);
 
 namespace Asseco\JsonQueryBuilder\Tests\Unit\SQLProviders;
 
@@ -26,27 +26,41 @@ public function test_it_returns_the_right_functions_query()
         }
     }
 
-    public function test_it_throws_an_exception_if_an_invalid_function_is_given()
-    {
-        $this->expectException(\Asseco\JsonQueryBuilder\Exceptions\JsonQueryBuilderException::class);
-        $this->functions::invalidFunction('id');
-    }
-
     public function test_it_validate_sql_functions()
     {
+        $this->expectNotToPerformAssertions();
         foreach (SQLFunctions::DB_FUNCTIONS as $fn) {
-            $this->assertNull($this->functions::validateArgument($fn . ':column'));
+            $this->functions::validateArgument($fn . ':column');
         }
     }
 
     public function test_it_validate_nested_functions_validation()
     {
-        $this->assertNull($this->functions::validateArgument('avg:year:column'));
+        $this->expectNotToPerformAssertions();
+        $this->functions::validateArgument('avg:year:column');
     }
 
     public function test_it_bypass_when_no_function_is_given()
     {
-        $this->assertNull($this->functions::validateArgument('column'));
+        $this->expectNotToPerformAssertions();
+        $this->functions::validateArgument('column');
+    }
+
+    public function test_it_validate_custom_aliases()
+    {
+        $this->expectNotToPerformAssertions();
+        $this->functions::validateArgument("avg:_column as my_avg");
+    }
+
+    public function test_it_throws_if_alias_is_not_valid() {
+        $this->expectException(\Asseco\JsonQueryBuilder\Exceptions\JsonQueryBuilderException::class);
+        $this->functions::validateArgument("avg:column as my_avg`ds");
+    }
+
+    public function test_it_throws_an_exception_if_an_invalid_function_is_given()
+    {
+        $this->expectException(\Asseco\JsonQueryBuilder\Exceptions\JsonQueryBuilderException::class);
+        $this->functions::invalidFunction('id');
     }
 
     public function test_it_throws_an_exception_if_an_invalid_argument_is_given()
@@ -58,7 +72,7 @@ public function test_it_throws_an_exception_if_an_invalid_argument_is_given()
     public function test_it_throws_an_exception_if_an_invalid_column_is_given()
     {
         $this->expectException(\Asseco\JsonQueryBuilder\Exceptions\JsonQueryBuilderException::class);
-        $this->functions::validateArgument("avg:'this--sql-scripting-is-invalid'");
+        $this->functions::validateArgument("avg:'this--sql-scripting-is-`invalid'");
     }
 
     public function test_it_throws_an_exception_if_no_column_is_given()

tests/Unit/Traits/DatabaseFunctionsTest.php

@@ -81,4 +81,11 @@ public function test_it_parses_right_count_all_query()
         $this->assertNull($parameter->run());
         $this->assertEquals('select count(*) as count', $this->builder->toSql());
     }
+
+    function test_it_should_use_the_right_alias_parameter()  {
+        app('config')->set('database.default', 'pgsql');
+        $parameter = new TestParameterClass(['avg:day:column as the_avg'], $this->builder, $this->modelConfig); 
+        $this->assertNull($parameter->run());
+        $this->assertEquals('select avg(EXTRACT(DAY FROM "column")) as the_avg', $this->builder->toSql());
+    }
 }