CODEWITHSUNDEEP
pythonsqlalchemyfastapi
Satvir Singh
Satvir Singh

Reputation: 121

FastAPI 'put' and 'patch' methods not working and is giving error 500

I am new to FastAPI and I am stuck at fastapi's put method. I am following a certain tutorial. Here is the code:

@app.put("/blog/{blog_id}", status_code=status.HTTP_202_ACCEPTED)
def update(blog_id: int, request: schemas.Blog,
           db: Session = Depends(get_db)):
    blog = db.query(models.Blog).filter(models.Blog.id == blog_id)
    if blog.first() is None:
        raise HTTPException(status_code=status.HTTP_404_NOT_FOUND,
                            detail="Blog not found")
    blog.update(request, synchronize_session=False)
    db.commit()
    return 'Blog updated'


@app.patch("/blog/{blog_id}", status_code=status.HTTP_202_ACCEPTED)
def partial_update(blog_id: int, request: schemas.Blog,
                   db: Session = Depends(get_db)):
    blog = db.query(models.Blog).filter(models.Blog.id == blog_id)
    if blog.first() is None:
        raise HTTPException(status_code=status.HTTP_404_NOT_FOUND,
                            detail="Blog not found")
    blog.update(request, synchronize_session=False)
    db.commit()
    return 'Blog updated'

but the thing it is not updating the contents and is giving error 500 if I try to update it. In console following error is shown:

File "/home/satvir/Documents/dev/FastApi_Tutorial/.env/lib/python3.9/site-packages/starlette/middleware/errors.py", line 159, in __call__
    await self.app(scope, receive, _send)
  File "/home/satvir/Documents/dev/FastApi_Tutorial/.env/lib/python3.9/site-packages/starlette/exceptions.py", line 82, in __call__
    raise exc from None
  File "/home/satvir/Documents/dev/FastApi_Tutorial/.env/lib/python3.9/site-packages/starlette/exceptions.py", line 71, in __call__
    await self.app(scope, receive, sender)
  File "/home/satvir/Documents/dev/FastApi_Tutorial/.env/lib/python3.9/site-packages/starlette/routing.py", line 566, in __call__
    await route.handle(scope, receive, send)
  File "/home/satvir/Documents/dev/FastApi_Tutorial/.env/lib/python3.9/site-packages/starlette/routing.py", line 227, in handle
    await self.app(scope, receive, send)
  File "/home/satvir/Documents/dev/FastApi_Tutorial/.env/lib/python3.9/site-packages/starlette/routing.py", line 41, in app
    response = await func(request)
  File "/home/satvir/Documents/dev/FastApi_Tutorial/.env/lib/python3.9/site-packages/fastapi/routing.py", line 201, in app
    raw_response = await run_endpoint_function(
  File "/home/satvir/Documents/dev/FastApi_Tutorial/.env/lib/python3.9/site-packages/fastapi/routing.py", line 150, in run_endpoint_function
    return await run_in_threadpool(dependant.call, **values)
  File "/home/satvir/Documents/dev/FastApi_Tutorial/.env/lib/python3.9/site-packages/starlette/concurrency.py", line 34, in run_in_threadpool
    return await loop.run_in_executor(None, func, *args)
  File "/usr/lib/python3.9/concurrent/futures/thread.py", line 52, in run
    result = self.fn(*self.args, **self.kwargs)
  File "/home/satvir/Documents/dev/FastApi_Tutorial/./Blog/main.py", line 64, in update
    blog.update(request, synchronize_session=False)
  File "/home/satvir/Documents/dev/FastApi_Tutorial/.env/lib/python3.9/site-packages/sqlalchemy/orm/query.py", line 3204, in update
    upd = upd.values(values)
  File "<string>", line 2, in values
  File "/home/satvir/Documents/dev/FastApi_Tutorial/.env/lib/python3.9/site-packages/sqlalchemy/sql/base.py", line 106, in _generative
    x = fn(self, *args, **kw)
  File "<string>", line 2, in values
  File "/home/satvir/Documents/dev/FastApi_Tutorial/.env/lib/python3.9/site-packages/sqlalchemy/sql/base.py", line 135, in check
    return fn(self, *args, **kw)
  File "/home/satvir/Documents/dev/FastApi_Tutorial/.env/lib/python3.9/site-packages/sqlalchemy/sql/dml.py", line 701, in values
    for k, v in arg.items()
AttributeError: 'Blog' object has no attribute 'items'

schemas.Blog:

class Blog(BaseModel):
    title: str
    content: str

models.Blog:

class Blog(Base):
    __tablename__ = "blogs"

    id = Column(Integer, primary_key=True, index=True)
    title = Column(String)
    description = Column(String)

Everything else: creating, retrieving, deleting methods are working fine. Please help me what to do??

Upvotes: 1

Views: 1440

Answers (1)

Toluwalemi
Toluwalemi

Reputation: 414

The solution is to change blog.update(request, synchronize_session=False) in your update function to :

blog.update(request.__dict__, synchronize_session=False)

I'll explain why.

From the error message provided, sqlalchemy is attempting to loop over a dictionary, hence it gives that error message when it cannot find a dict type.

The request parameter in blog.update() method is of type Class. To confirm, add this line of code after your if statement:

print(type(request))

You should get an output similar to:

<class 'blog.schemas.Blog'>

Hence, the error. Now do this: print(type(request.__dict__)). Your output should be similar to this: <class 'dict'> which solves the problem.

Upvotes: 1

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