get doctype name statically

[KlausH09]

This pull request introduces a new static method, get_doctype_name, to the base Document class in Frappe. The goal of this enhancement is to facilitate type-safe interactions with documents, particularly when using the frappe.get_doc function. By implementing get_doctype_name, developers can retrieve the Doctype name directly from the class, improving maintainability and readability of the code that interacts with Frappe's ORM layer.

Questions for the Maintainers

Before finalizing this implementation, I'd like to verify if there's an existing method or pattern within Frappe that already addresses this requirement. If so, guidance on how to better integrate or utilize existing functionalities would be greatly appreciated.

Use Case

Currently, when developers need to dynamically fetch documents, they have to manually pass the Doctype name as a string, which can lead to errors if there are changes in the Doctype name or if the name is misspelled. This feature aims to eliminate such issues by allowing the following type-safe method of fetching documents:

from typing import TypeVar, Type
from frappe.model.document import Document

T = TypeVar("T", bound=Document)

def get_doc_typed(cls: Type[T], name: str) -> T:
    doctype_name = cls.get_doctype_name()
    return frappe.get_doc(doctype_name, name)


# example:
from frappe.core.doctype.user_group.user_group import UserGroup
my_group = get_doc_typed(UserGroup, "Example")  # type of my_group is UserGroup

[ankush]

Merging this might be better and more pythonic: #13223

from frappe.core.doctype.user_group.user_group import UserGroup
my_group = UserGroup("Example")

While I've given up on this being the default way to write code, offering it as an option seems fine 😄

[KlausH09]

Thank you @ankush for reviewing my pull request and for pointing out alternative #13223. I appreciate the suggestion to use object instantiation directly for loading doctypes. However, I have some concerns about adopting this approach as a standard practice, particularly around the use of the __init__ method for this purpose.

Using the __init__ method to load data from the database can potentially lead to less clear and predictable code. Typically, constructors (__init__ methods) are used for initializing new objects, not for fetching existing data from a database. Instead, a class method, like get_doc, that explicitly handles database operations, might provide clearer semantics.

But the primary intention behind my pull request was to offer developers a straightforward way to obtain the Doctype name, enhancing the flexibility in how they might choose to implement features like those proposed in #13223 or others.

If this approach aligns with the project's goals, I'm more than happy to assist further, perhaps by updating the auto-generated code for doctypes to include this new method. Please let me know if there's anything specific you would like me to address or any other contributions I can make to help integrate this feature into the codebase effectively.

[Mutantpenguin]

I am with @KlausH09 so as to not abuse the constructor for fetching data.

Let me throw another alternative into the ring:

UserGroup.get("id_here")
UserGroup.new()
UserGroup.delete("id_here")

[ankush]

Constructor already does this 😄 It's just that almost no one knows or uses it.

Try this:

from frappe.core.doctype.user.user import User
user = User("User", "Administrator")

[Mutantpenguin]

Oh boy. I don't think this should be further brought forward. ^^

[KlausH09]

The primary intention behind my pull request was to offer developers a straightforward way to obtain the Doctype name. Please take a look at the file changes!

I have only given theget_doc_typed function as an example of how to use this feature. And the proposed class methods from @Mutantpenguin are also just another use case. But this can all be discussed and implemented in a new PR.

So @ankush, is there anything I can do to get my PR accepted? For example, does it make sense for me to update the auto-generated code of the existing doctypes?

[ankush]

TBH I don't like this API as of now so I'll pass on this PR.

Importing a class and using another function to get typed document doesn't seem elegant to me. It should be done using the same class only.

Maybe another namespace is required like Django Class.objects.get(id=id)