grails addTo 为 hasMan 关系输入重复数据
我有一个非常简单的 hasMany 关系，其中“产品”有许多“包”。我正在运行一个脚本来尝试填充数据，第一次运行时效果很好。然而，在第二次运行时，它开始输入重复项，我认为这对于 hasMany 来说是不可能的。
package = Package.findBySourceId(packageId) ?: new Package(name:packageName, price:packagePrice, sourceId:packageId).save(flush:true)
product = Product.findBySourceId(productId)
product.addToPackages(package)
product.save(flush:true)
当我打开 sql 日志记录时，我可以看到有时应该在 addToPackages 调用上运行的选择没有运行。它只是执行选择来查找产品，然后直接插入到连接表中。
由于工作原因，我不想添加确切的查询，但基本上就像这样
Select -> for the initial package which it finds
Select -> for product which it finds by the product id
Insert -> insert into the join table without even a select to check if an entry exists
，但是有时它会运行选择并找到匹配项，而不是插入，并且该过程将重新开始。不知道这里 grails 背后的逻辑。请记住，我正在运行一个脚本，该脚本正在提取数千行数据，这是否是会话问题？
I have a pretty simple hasMany relationship where a "product" hasMany "packages". I'm running a script to try and fill in the data, which works fine on the first run. However on the second run, it starts inputing duplicates, which I though was not possible for a hasMany
package = Package.findBySourceId(packageId) ?: new Package(name:packageName, price:packagePrice, sourceId:packageId).save(flush:true)
product = Product.findBySourceId(productId)
product.addToPackages(package)
product.save(flush:true)
When I put on sql logging on, I can see that sometimes the select that should run on the addToPackages call is not run. It just does the select to find the product and then a straight insert into the join table.
I don't want to add the exact queries because of work but basically its like
Select -> for the initial package which it finds
Select -> for product which it finds by the product id
Insert -> insert into the join table without even a select to check if an entry exists
However sometimes instead of that insert it will run a select and find the match and the process will start over. No idea on the logic going on behind grails here. Keep in mind, I have a script running that's pulling the data with thousands of line, is this a session issue somehow?
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您是否在一对多的“多”方面使用过 List 或 Set 来进行集合？默认值是一个 Set，它应该限制重复。如果您使用列表映射集合，那么您可能已经造成了问题。
或者，验证身份属性“package”对于 equals() 和 hashCode() 是否具有正确的行为。
Have you used a List or Set for your collection on the "many" side of your one-to-many? The default is a Set, which should constrain against duplicates. If you've mapped the collection using a List, then you may have created the problem.
Alternatively, verify that the identity property "package" has the correct behaviors for equals() and hashCode().
看
使用列表的 Domain hasMany 关联在保存父项时添加重复项
See
Domain hasMany association using a List is adding duplicate items when the parent is saved