How to remove free form "tags" from domain-class?
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I've created 2 domain classes called Asset and Tag. Asset can have many Tags

    // Asset.groovy
    class Asset {
        static hasMany = [tags: Tag]
    }

    // Tag.groovy
    class Tag {
        static belongsTo = Asset
        String word
    }

The tags are entered into a textfield in the View, each separated by commas.

When the Asset form is submitted, the AssetController will use `Tag.findOrSaveWhere` to either create a new Tag or `Asset.addToTag`

    def tags_list = params?.tags?.split(",")
    tags_list.each {
        def tag = Tag.findOrSaveWhere(word: it.trim())
        assetInstance.addToTags(tag)
    }

All that works very well, but I'm trying to essentially remove Tags from an Asset if the user updates and deleted a Tag.

How can I remove Tags on update?