Filter by a field that's a foreign key - yii

Question

Using Yii2.
I have a table called 'calificacion' that has a foreign key 'alumno-id' that points to field id in table alumno.
The column defined in the GridView widget is:
[
'header' => 'Alumno',
'attribute' => 'alumno.id',
'value' => 'alumno.name'
],
And it's showing perfectly, but the filter, in the header of the column, is not appearing. I want to have a textbox for writing the name of the alumno and get filtered. How can I achieve that?
EDIT: Here're the files https://dl.dropboxusercontent.com/u/7059378/Desktop.zip

Answer 1

First declare an attribute in your SearchModel.
public $alumno_name;
In your search model's rule add:
[['alumno_name'], 'safe'],
Join with alumno relation in search method (supponsinbly there is a alumno relation in your Calificacion model):
$query = Calificacion::find()
->joinWith(['alumno alumno']);
To sort with $alumno_name add:
$dataProvider->sort = [
'attributes' => [
//Other attributes here
'alumno_name' => [
'asc' => ['alumno.name' => SORT_ASC],
'desc' => ['alumno.name' => SORT_DESC],
],
]
];
To filter this you have to add:
$query->andFilterWhere(['like', 'alumno.name', $this->alumno_name]);
Finally in your grid view add:
[
'attribute' => 'alumno_name',
'value' => 'alumno.name'
],
You can find more info here and here.
Also instead of header use 'label' => 'Alumno'.

Answer 2

You must first define a relation in Model of that table 'calificacion', like
public function getAlumno()
{
return $this->hasOne(Alumno::className(), ['id' => 'alumno_id']);
}
Than in the search model of Calificacion set that you are joining tables after validation, like
$query->joinWith('alumno');
Than set search like
$query->andFilterWhere([
'alumno.id' => $this.alumno_id
]);