from django.db import models

class CurrentTranslation(models.ForeignObject):

    """

    Creates virtual relation to the translation with model cache enabled.

    """

    # Avoid validation

    requires_unique_target = False

    def __init__(self, to, on_delete, from_fields, to_fields, **kwargs):

        # Disable reverse relation

        kwargs["related_name"] = "+"

        # Set unique to enable model cache.

        kwargs["unique"] = True

        super().__init__(to, on_delete, from_fields, to_fields, **kwargs)

class ArticleTranslation(models.Model):

    article = models.ForeignKey("indexes.Article", models.CASCADE)

    article_no_constraint = models.ForeignKey(

        "indexes.Article", models.CASCADE, db_constraint=False, related_name="+"

    )

    language = models.CharField(max_length=10, unique=True)

    content = models.TextField()

class Article(models.Model):

    headline = models.CharField(max_length=100)

    pub_date = models.DateTimeField()

    published = models.BooleanField(default=False)

    # Add virtual relation to the ArticleTranslation model.

    translation = CurrentTranslation(

        ArticleTranslation, models.CASCADE, ["id"], ["article"]

    )

    class Meta:

        index_together = [

            ["headline", "pub_date"],

        ]

# Model for index_together being used only with single list

class IndexTogetherSingleList(models.Model):

    headline = models.CharField(max_length=100)

    pub_date = models.DateTimeField()

    class Meta:

        index_together = ["headline", "pub_date"]

class IndexedArticle(models.Model):

    headline = models.CharField(max_length=100, db_index=True)

    body = models.TextField(db_index=True)

    slug = models.CharField(max_length=40, unique=True)

    class Meta:

        required_db_features = {"supports_index_on_text_field"}

class IndexedArticle2(models.Model):

    headline = models.CharField(max_length=100)

    body = models.TextField()