index: add composite id

[photon3108]

• Do only one thing
• Non breaking API changes
• Tested

What did this pull request do?

In the issue #3973, if a struct with any composite indexes, these indexes will be invalid when the struct is embedded more than once. Because a composite index must specify its name, embedding more than once results in the duplicated name in db. Also if the name of index is specified manually, NamingStrategy will not be applied. Take the example of #3973:

type Bar0 struct {
  Foo
}
type Bar1 struct {
  Foo
}

Both Bar0 and Bar1 will try to create an index of the same name my_idx. In this pull request, it provides a new field of index tag which is named to composite. It means the id of composite index. All fields which have the same composite id of the struct are put together to the same index, just like the original rule. But the improvement is it lets the most derived/embedding struct generates the name of index by NamingStrategy. For example:

type Foo struct {
  IndexA int `gorm:"index:,unique,composite:myname"`
  IndexB int `gorm:"index:,unique,composite:myname"`
}

If the table Foo is created, the name of composite index will be idx_foo_myname.

type Bar0 struct {
  Foo
}
type Bar1 struct {
  Foo
}

Respectively, the name of composite index are idx_bar0_myname and idx_bar1_myname.

composite only works if not specify the name of index, so it keeps the original API from being broken.

[jinzhu]

Hello,

@photon3108 can you add a test to index_test.go to test the composite logic.

Thank you.

[daheige]

To support this change, you still need to provide unit tests, which is more reliable.

…

------------------ Original ------------------ From: Jinzhu ***@***.***> Date: Sun,Apr 24,2022 9:31 AM To: go-gorm/gorm ***@***.***> Cc: heige ***@***.***>, Comment ***@***.***> Subject: Re: [go-gorm/gorm] index: add composite id (PR #5269) Hello, @photon3108 can you add a test to index_test.go to test the composite logic. Thank you. — Reply to this email directly, view it on GitHub, or unsubscribe. You are receiving this because you commented.Message ID: ***@***.***>