Here's the `comments.py` file for the `app/api/v1/models/` directory in the `blog_app_igblf` FastAPI backend:

from sqlalchemy import Column, ForeignKey, Integer, String, Text
from sqlalchemy.orm import relationship

from app.db.base_class import Base

class Comment(Base):
    __tablename__ = "comments"

    id = Column(Integer, primary_key=True, index=True)
    text = Column(Text, nullable=False)
    user_id = Column(Integer, ForeignKey("users.id"), nullable=False)
    post_id = Column(Integer, ForeignKey("posts.id"), nullable=False)

    user = relationship("User", back_populates="comments")
    post = relationship("Post", back_populates="comments")

    def __repr__(self):
        return f"Comment(id={self.id}, text='{self.text[:20]}...', user_id={self.user_id}, post_id={self.post_id})"

Explanation:

1. We import the necessary modules from SQLAlchemy: `Column`, `ForeignKey`, `Integer`, `String`, `Text`, and `relationship`.
5. We define the columns for the `Comment` model:
   - `id`: an integer primary key and index column.
   - `text`: a text column for the comment content, which is required (`nullable=False`).
   - `user_id`: an integer foreign key column referring to the `users` table, which is required (`nullable=False`).
   - `post_id`: an integer foreign key column referring to the `posts` table, which is required (`nullable=False`).
6. We define the relationships between the `Comment` model and the `User` and `Post` models using the `relationship` function from SQLAlchemy:
   - `user`: a one-to-many relationship with the `User` model, using the `back_populates` parameter to enable bi-directional access.
   - `post`: a one-to-many relationship with the `Post` model, using the `back_populates` parameter to enable bi-directional access.