map insert support return increment id

[FangSqing]

• Do only one thing

• Non breaking API changes

• Tested

What did this pull request do?

This pull request aims to support returning the primary key value, when using a map (or map list) to call GORM to insert record, in auto-increment primary key case.

If the primary key value is not set, the returned map or map list will be filled with a custom column "@id".

User Case Description

The following cases are all using auto-increment primary key
Case 1:
  Input: map or map list without primary key
  Output: map or map list will be filled with "@id"
Case 2:
  Input: map or map list with primary key
  Output: map or map list will be filled with "@id"

The following cases are all using non-auto-increment primary key
Case 1:
  Input: map or map list without primary key
  Output: error, the same as before.
Case 2:
  Input: map or map list with primary key
  Output: the same as before

Last but not least, it has no impact on non-auto-increment primary keys.

[jinzhu]

In some cases, the Dest might be a map value, but db.Statement.Schema is not nil, for example:

db.Model(&User{}).First(map[string]interface{}{})

[jinzhu]

btw, can you add some test cases for the feature, thank you.

[a631807682]

https://github.com/go-gorm/gorm/pull/6662/files#diff-7539aa7c170a85138fa67c7846b65fda95a51169bcf8637d5961ea570307d755R52

Since the detection of RETURNING does not support map, an error will occur if the driver only supports returning but not LastInsertId (the database usually only supports one).
We need to change the detection of RETURNING if we want to support this feat.

related to #6812

[sujit-baniya]

This PR creates bug for inserting rows (slice of map) in batches for Postgres

Error: LastInsertId is not supported by this driver

[FangSqing]

Sorry, I’ll check it and fix it with a new PR.

[thesiti92]

I also cannot update gorm because this breaks inserting a map of values in postgres. Thanks for working on a fix!

[sujit-baniya]

For the time being, till the issue is fixed, I've been checking for the error message.

master...sujit-baniya:gorm:master

[zh929]

if I use createForUpdate logic，and the same logic is executed simultaneously in multiple databases，if not set Model, just know the table name. the same map will add “@id”，causing some SQL statements to fail execution. For example:
`

    updateList := make([]map[string]interface{}, 0)  // the map will be add '@id'   

    columns := make([]clause.Column, 0)    

    updateColumns := make([]string, 0)  

 for _, v := range req.dbList {   
                   dbName := v

		db := global.GVA_DBList[dbName]  

		err := db.Table(req.table).Clauses(clause.OnConflict{  

			Columns:   columns,  
                            
			DoUpdates: clause.AssignmentColumns(updateColumns),   

		}).Create(&updateList).Error  
		if err != nil {  
			errDbList = append(errDbList, dbName)  
			isAllDone = false  
		}  
}  

`
Error Msg: Error 1054 (42S22): Unknown column '@id' in 'field list'