: Is there an article about ThinkPHP's business model and controller instance?

Is there an article about ThinkPHP's business model and controller instance ?? For example, I searched a lot on the Internet, but they were all one-sided. the official documents seem to have no source code, I cannot figure out the relationship between the business model and the controller, or even I don't know how to write the business model... very depressing. can I provide some source code instances ?? To be complete, at least one complete class is required. how does the controller call the business model? I know for help: Is there an article about ThinkPHP's business model and controller instance ??
For example, I searched a lot on the Internet, but they were all one-sided. the official documents seem to have no source code, I cannot figure out the relationship between the business model and the controller, or even I don't know how to write the business model... very depressing. can I provide some source code instances ?? To be complete, at least one complete class is required. how does the controller call the business model? I know there is a M () and D (), but it seems that it cannot be called .....
In learning TP, thank you ....
It seems that there is very little information about the business model on the Internet, all of which is an excerpt from the official documentation... very depressing.

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Does he have Examples?
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Why can't M and D be called? This is the most basic usage
Is M ("user ").
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Go to the smarty Chinese manual. it's comprehensive!