Created
May 21, 2020 19:31
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Automatic model migration for Postgres
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func migrate(db *pg.DB, tables ...[]T) chan error { | |
errfeed := make(chan error) | |
go func() { | |
for _, model := range tables { | |
err := db.CreateTable(model, &orm.CreateTableOptions{IfNotExists: true}) | |
if err != nil { | |
errfeed <- err | |
continue | |
} | |
table := orm.GetTable(reflect.TypeOf(model).Elem()) | |
columns := make([]string, 0, len(table.Fields)) | |
for _, field := range table.Fields { | |
columns = append(columns, `"`+field.SQLName+`" `+field.SQLType) | |
} | |
err = db.RunInTransaction(func(tx *pg.Tx) error { | |
for i, column := range columns { | |
query := fmt.Sprintf("ALTER TABLE %s ADD COLUMN IF NOT EXISTS %s", | |
table.Name, column) | |
defaultExpr := table.Fields[i].Default | |
if defaultExpr != "" { | |
query += " DEFAULT (" + string(defaultExpr) + ")" | |
} | |
if pgTag, ok := table.Fields[i].Field.Tag.Lookup("pg"); ok { | |
if strings.Contains(pgTag, "notnull") { | |
query += " NOT NULL" | |
} | |
} | |
_, err := tx.Exec(query) | |
if err != nil { | |
fmt.Println(query) | |
errfeed <- err | |
continue | |
} | |
} | |
return nil | |
}) | |
if err != nil { | |
errfeed <- err | |
} | |
} | |
close(errfeed) | |
}() | |
return errfeed | |
} |
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