[RUBY] [Rails] first_or_initialize

Since we learned about first_or_initialize, we will output it.

What is first_or_initialize? How to use first_or_initialize?

Describe in the order of.

What is first_or_initialize?

If the record of the condition searched by where exists, an instance of that record is returned, and if it does not exist, a new instance is created.

It's hard to understand, right? I will explain in detail.

For example Suppose there is a table called student, and each of the 10 names is registered in the database there.

The first_or_initialize method If the student does not exist in the database → Register the student newly. on the other hand, If a student is already registered → Get information about that student.

Did you understand little by little?

That is, the feature of this method is "Avoid duplication of data".

So how do you use it?

How to use first_or_initialize

student = Student.where(name: "Sato").first_or_initialize

If it doesn't exist, define the object you want to create a new instance of, After that where (condition) .first_or_initialize Then it is completed.

In the above example If Mr. Sato is not in the database → Register the Sato newly. on the other hand, Mr. Sato If you have already registered → Get Mr. Sato's information (defined id, age, etc.).

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