Debugging

When working with the API, chances are you’ll stumble upon bugs, get stuck and start wondering how to continue. Nothing to actually worry about since Hydrogram provides some commodities to help you in this.


Caveman Debugging

The most effective debugging tool is still careful thought, coupled with judiciously placed print statements.

—Brian Kernighan, “Unix for Beginners” (1979)

Adding print() statements in crucial parts of your code is by far the most ancient, yet efficient technique for debugging programs, especially considering the concurrent nature of the framework itself. Hydrogram goodness in this respect comes with the fact that any object can be nicely printed just by calling print(obj), thus giving to you an insight of all its inner details.

Consider the following code:

me = await app.get_users("me")
print(me)  # User

This will show a JSON representation of the object returned by get_users(), which is a User instance, in this case. The output on your terminal will be something similar to this:

{
    "_": "User",
    "id": 123456789,
    "is_self": true,
    "is_contact": false,
    "is_mutual_contact": false,
    "is_deleted": false,
    "is_bot": false,
    "is_verified": false,
    "is_restricted": false,
    "is_support": false,
    "first_name": "Hydrogram",
    "photo": {
        "_": "ChatPhoto",
        "small_file_id": "AbCdE...EdCbA",
        "small_photo_unique_id": "VwXyZ...ZyXwV",
        "big_file_id": "AbCdE...EdCbA",
        "big_photo_unique_id": "VwXyZ...ZyXwV"
    }
}

As you’ve probably guessed already, Hydrogram objects can be nested. That’s how compound data are built, and nesting keeps going until we are left with base data types only, such as str, int, bool, etc.

Accessing Attributes

Even though you see a JSON output, it doesn’t mean we are dealing with dictionaries; in fact, all Hydrogram types are fully-fledged Python objects and the correct way to access any attribute of them is by using the dot notation .:

photo = me.photo
print(photo)  # ChatPhoto
{
    "_": "ChatPhoto",
    "small_file_id": "AbCdE...EdCbA",
    "small_photo_unique_id": "VwXyZ...ZyXwV",
    "big_file_id": "AbCdE...EdCbA",
    "big_photo_unique_id": "VwXyZ...ZyXwV"
}

Checking an Object’s Type

Another thing worth talking about is how to tell and check for an object’s type.

As you noticed already, when printing an object you’ll see the special attribute "_". This is just a visual thing useful to show humans the object type, but doesn’t really exist anywhere; any attempt in accessing it will lead to an error. The correct way to get the object type is by using the built-in function type():

status = me.status
print(type(status))
<class 'hydrogram.types.UserStatus'>

And to check if an object is an instance of a given class, you use the built-in function isinstance():

from hydrogram.types import UserStatus

status = me.status
print(isinstance(status, UserStatus))
True