add DateTime threshold filter

README.md

@@ -49,6 +49,7 @@ Documentation
   * [Filters](#filters)
     - [CallbackFilter](#callbackfilter)
     - [OffsetFilter](#offsetfilter)
+    - [DateTimeThresholdFilter](#datetimethresholdfilter)
     - [ValidatorFilter](#offsetfilter)
   * [Converters](#converters)
     - [Item converters](#item-converters)
@@ -733,6 +734,23 @@ $filter = new OffsetFilter(0, 3);
 $filter = new OffsetFilter(2, 5);
 ```
 
+#### DateTimeThresholdFilter
+
+This filter is useful if you want to do incremental imports. Specify a threshold
+`DateTime` instance, a column name (defaults to `updated_at`), and a
+`DateTimeValueConverter` that will be used to convert values read from the
+filtered items. The item strictly older than the threshold will be discarded.
+
+```php
+use Ddeboer\DataImport\Filter\DateTimeThresholdFilter;
+use Ddeboer\DataImport\ValueConverter\DateTimeValueConverter;
+
+new DateTimeThresholdFilter(
+    new DateTimeValueConverter(),
+    new \DateTime('yesterday')
+);
+```
+
 #### ValidatorFilter
 
 It’s a common use case to validate the data before you save it to the database.

src/Ddeboer/DataImport/Filter/DateTimeThresholdFilter.php

@@ -0,0 +1,80 @@
+<?php
+
+namespace Ddeboer\DataImport\Filter;
+
+use Ddeboer\DataImport\ValueConverter\DateTimeValueConverter;
+
+/**
+ * This filter can be used to filter out some items from a specific date. Useful
+ * to do incremental imports
+ */
+class DateTimeThresholdFilter implements FilterInterface
+{
+    /**
+     * @var DateTime threshold dates strictly before this date will be filtered out.
+     *               defaults to null
+     */
+    protected $threshold;
+
+    /**
+     * @var DateTimeValueConverter used to convert the values in the time column
+     */
+    protected $valueConverter;
+
+    /**
+     * @var string the name of the column that should contain the value the
+     *             filter will compare the threshold with. Defaults to "updated_at"
+     */
+    protected $timeColumnName;
+
+    /**
+     * @var int priority the filter priority. Defaults to 512.
+     */
+    protected $priority;
+
+    public function __construct(
+        DateTimeValueConverter $valueConverter,
+        \DateTime $threshold = null,
+        $timeColumnName = 'updated_at',
+        $priority = 512
+    ) {
+        $this->valueConverter = $valueConverter;
+        $this->threshold = $threshold;
+        $this->timeColumnName = $timeColumnName;
+        $this->priority = $priority;
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    public function filter(array $item)
+    {
+        if ($this->threshold == null) {
+            throw new \LogicException('Make sure you set a threshold');
+        }
+
+        return
+            $this->valueConverter->convert($item[$this->timeColumnName])
+            >=
+            $this->threshold;
+    }
+
+    /**
+     * Useful if you build a filter service, and want to set the threshold
+     * dynamically afterwards.
+     */
+    public function setThreshold(\DateTime $value)
+    {
+        $this->threshold = $value;
+
+        return $this;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function getPriority()
+    {
+        return $this->priority;
+    }
+}

tests/Ddeboer/DataImport/Tests/Filter/DateTimeFilterTest.php

@@ -0,0 +1,63 @@
+<?php
+
+namespace Ddeboer\DataImport\Filter;
+
+use Ddeboer\DataImport\Filter\DateTimeThresholdFilter;
+use Ddeboer\DataImport\ValueConverter\DateTimeValueConverter;
+
+class DateTimeFilterTest extends \PHPUnit_Framework_TestCase
+{
+    public function setUp()
+    {
+        $this->items = array(
+            'a' => array('updated_at' => '-3 day'),
+            'b' => array('updated_at' => '-2 day'),
+            'c' => array('updated_at' => '-1 day'),
+            'd' => array('updated_at' => 'today'),
+            'e' => array('updated_at' => 'now'),
+            'f' => array('updated_at' => '+1 day'),
+        );
+    }
+
+    private function applyFilter(DateTimeThresholdFilter $filter, array $items)
+    {
+        return array_filter($items, array($filter, 'filter'));
+    }
+
+    /**
+     * @expectedException \LogicException
+     * @expectedExceptionMessage Make sure you set a threshold
+     */
+    public function testDefaultFilter()
+    {
+        $resultItems = $this->applyFilter(
+            new DateTimeThresholdFilter(new DateTimeValueConverter()),
+            $this->items
+        );
+    }
+
+    public function testFilter()
+    {
+        $resultItems = $this->applyFilter(new DateTimeThresholdFilter(
+            new DateTimeValueConverter(),
+            new \DateTime('today')
+        ), $this->items);
+        $this->assertEquals(
+            array('d', 'e', 'f'),
+            array_keys($resultItems)
+        );
+    }
+
+    public function testSetter()
+    {
+        $filter = new DateTimeThresholdFilter(new DateTimeValueConverter());
+        $filter->setThreshold(new \DateTime('today'));
+        $resultItems = $this->applyFilter($filter, $this->items);
+
+
+        $this->assertEquals(
+            array('d', 'e', 'f'),
+            array_keys($resultItems)
+        );
+    }
+}