feat: constant columns

Author: yajra

README.md

@@ -143,9 +143,10 @@ $loader->into('employees', ['name', 'dept_id']);
 Using `withHeaders` will skip the first row of the CSV file. 
 
 > **IMPORTANT** 
-> This method assumes that the headers are the same as the columns.
-> If the headers are different from the columns, you should define the `columns` in the `into` method.
-> This works well with the Eloquent Collection as the data source and saving it to a CSV file for bulk import.
+> 1. `withHeaders` must be called before the `into` method.
+> 2. This method assumes that the headers are the same as the columns. 
+> 3. If the headers are different from the columns, you should define the `columns` in the `into` method. 
+> 4. This works well with the Eloquent Collection as the data source and saving it to a CSV file for bulk import.
 
 #### Building a CSV File from Eloquent Collection
 
@@ -197,6 +198,23 @@ John Doe,1
 Jane Doe,2
 ```
 
+### Constants
+
+In some cases, we need to insert constant values to the table. You can use the `constants` method to set the constant value.
+
+> **IMPORTANT**
+>`constants` must be called before the `into` method.
+
+```php
+$loader->withHeaders()
+    ->constants([
+        'file_id CONSTANT 1',
+        'created_at EXPRESSION "current_timestamp(3)"',
+        'updated_at EXPRESSION "current_timestamp(3)"',
+    ])
+    ->into('users');
+```
+
 ### Connection
 
 You can set the connection name to use for the SQL*Loader command using the `connection` method.

src/SQLLoader.php

@@ -32,6 +32,8 @@ class SQLLoader
 
     protected array $defaultColumns = [];
 
+    public array $constants = [];
+
     protected ?string $disk = null;
 
     protected ?string $logPath = null;
@@ -83,6 +85,8 @@ public function into(
             ];
         }
 
+        $columns = array_merge($columns, $this->constants);
+
         $this->tables[] = new TableDefinition(
             $table, $columns, $terminatedBy, $enclosedBy, $trailing, $formatOptions, $when
         );
@@ -470,4 +474,11 @@ public function dateFormat(string $format): static
 
         return $this;
     }
+
+    public function constants(array $constants): static
+    {
+        $this->constants = $constants;
+
+        return $this;
+    }
 }

tests/Feature/SQLLoaderTest.php

@@ -230,3 +230,30 @@
         ->toContain("TIMESTAMP WITH TIME ZONE 'YYYY-MM-DD'\n")
         ->toContain("TIMESTAMP WITH LOCAL TIME ZONE 'YYYY-MM-DD'\n");
 });
+
+test('it can process constants columns', function () {
+    Process::fake();
+
+    $loader = new SQLLoader();
+    $loader->inFile(__DIR__.'/../data/users.dat')
+        ->as('users.ctl')
+        ->withHeaders()
+        ->constants([
+            'created_by CONSTANT 1',
+            'created_at EXPRESSION "current_timestamp(3)"',
+            'updated_by CONSTANT 1',
+            'updated_at EXPRESSION "current_timestamp(3)"',
+        ])
+        ->into('users')
+        ->execute();
+
+    $controlFile = $loader->buildControlFile();
+
+    expect($controlFile)->toBeString()
+        ->toContain("\"NAME\",\n")
+        ->toContain("\"EMAIL\",\n")
+        ->toContain("created_by CONSTANT 1,\n")
+        ->toContain("created_at EXPRESSION \"current_timestamp(3)\",\n")
+        ->toContain("updated_by CONSTANT 1,\n")
+        ->toContain("updated_at EXPRESSION \"current_timestamp(3)\"\n");
+});