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			34 lines
		
	
	
		
			795 B
		
	
	
	
		
			Go
		
	
	
	
	
	
			
		
		
	
	
			34 lines
		
	
	
		
			795 B
		
	
	
	
		
			Go
		
	
	
	
	
	
| package conversion
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| 
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| import (
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| 	"fmt"
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| 
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| 	"gorm.io/gorm"
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| 	"gorm.io/gorm/schema"
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| )
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| 
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| func FindAndInsert[V2 any, V3 schema.Tabler](v2db *gorm.DB, v3db *gorm.DB, fn func(V2) V3) (string, error) {
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| 	var t V3
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| 	name := t.TableName()
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| 	if err := v3db.AutoMigrate(&t); err != nil {
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| 		return name, fmt.Errorf("auto migrate v3 %s failed %w", name, err)
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| 	}
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| 	const size = 100
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| 	for i := 0; ; i++ {
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| 		var v2s []V2
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| 		if err := v2db.Offset(i * size).Limit(size).Find(&v2s).Error; err != nil {
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| 			return name, fmt.Errorf("find v2 %s failed %w", name, err)
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| 		}
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| 		if len(v2s) == 0 {
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| 			return name, nil
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| 		}
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| 		v3s := make([]V3, 0, len(v2s))
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| 		for _, v := range v2s {
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| 			v3s = append(v3s, fn(v))
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| 		}
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| 		if err := v3db.Create(&v3s).Error; err != nil {
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| 			return name, fmt.Errorf("insert v3 %s failed %w", name, err)
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| 		}
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| 	}
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| }
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