Magento: select from database

Question

I am working on my first module for magento version 1.3.2.3. I have created a simple table (not EAV, just a primary key and 2 columns) and some classes to access it, following Alan Storm's articles which helped me a lot, but I can't figure out how to make a simple select: Alan explains how to load with the primary key, but not selecting rows that match some value.

In normal MySQL I'd write:

SELECT *  
FROM my_table  
WHERE some_field = '" . $someValue . "'  

I've found a snippet which gives me the result I want:

$resource = new Mage_Core_Model_Resource();  
$read = $resource->getConnection('core_read');  
$select = $read->select()
               ->from('my_table')
               ->where('some_field = ?', $someValue);  
return $read->fetchAll($select);  

But there have to be an easier/prettier solution, using the model class I've created. The result will be a single row, not a collection.
I've tried everything I could think of, like:

return Mage::getModel('modulename/classname')->select()->where('some_field = ?', $comeValue);
return Mage::getModel('modulename/classname')->load()->where('some_field = ?', $comeValue);  
return Mage::getModel('modulename/classname')->load(array('some_field = ?', $comeValue));  

and more stuff, but no luck so far: what am I missing??

Answer 1

You probably want to use your model's Collection for that.

$collection = Mage::getModel('mygroup/mymodel')->getCollection();
$collection->addFieldToFilter('some_field',$some_value);

foreach($collection as $item)
{
    var_dump($item);
}

var_dump($collection->getFirstItem());
var_dump($collection->getLastItem());

Answer 2

Here's an example of how this is achieved in the CoreUrlRewrite Model class:

public function loadByIdPath($path)
{
    $this->setId(null)->load($path, 'id_path');
    return $this;
}

You can create similar methods in your model classes. You can also use the alternative form of the load method anywhere in your code:

$model = Mage::getModel('modulename/classname')->load($someValue, 'some_field');