Grails GORM でツリーのような構造を作成したいと考えています。構造は他のオブジェクトのコンテナである必要があり、次の要件を完全に満たす必要があります。
- ノードには 0 から n 個の子が必要です
- ノードは 1 つの親ノードを持つ必要があります
- ノードには 0 から n 個の兄弟ノードが必要です
Grails GORM でそのような構造を定義するにはどうすればよいですか?
私は次のクラスを試しました：
Class TreeNode {
String name
TreeNode parent
static hasMany = [children: TreeNode]
//returns the root node, and by extension, the entire tree!
TreeNode getRootNode(){
if(parent){
//if parent is not null then by definition this node is a child node of the tree.
return parent.getRootNode()
}else{
//if parent is null then by definition it is the root node.
return this
}
}
//you might not need this function, but ill add it as it is common in tree structures
boolean isLeaf(){
//determines if this node is a leaf node. a leaf is a node with zero childrens
return children.isEmpty()
}
}
しかし、起動時に次のエラーが発生します。
ERROR context.ContextLoader - Context initialization failed
Message: Error creating bean with name 'pluginManager' defined in ServletContext resource [/WEB-INF/applicationContext.xml]: Invocation of init method failed; nested exception is org.codehaus.groovy.grails.exceptions.GrailsDomainException: Property [children] in class [class test.TreeNode] is a bidirectional one-to-many with two possible properties on the inverse side. Either name one of the properties on other side of the relationship [treeNode] or use the 'mappedBy' static to define the property that the relationship is mapped with. Example: static mappedBy = [children:'myprop']
Line | Method
->> 334 | innerRun in java.util.concurrent.FutureTask$Sync
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
| 166 | run in java.util.concurrent.FutureTask
| 1145 | runWorker in java.util.concurrent.ThreadPoolExecutor
| 615 | run in java.util.concurrent.ThreadPoolExecutor$Worker
^ 722 | run . . . in java.lang.Thread
Caused by GrailsDomainException: Property [children] in class [class test.TreeNode] is a bidirectional one-to-many with two possible properties on the inverse side. Either name one of the properties on other side of the relationship [treeNode] or use the 'mappedBy' static to define the property that the relationship is mapped with. Example: static mappedBy = [children:'myprop']
->> 334 | innerRun in java.util.concurrent.FutureTask$Sync
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
| 166 | run in java.util.concurrent.FutureTask
| 1145 | runWorker in java.util.concurrent.ThreadPoolExecutor
| 615 | run in java.util.concurrent.ThreadPoolExecutor$Worker
^ 722 | run . . . in java.lang.Thread
| Error 2013-10-04 17:36:00,730 [localhost-startStop-1] ERROR context.GrailsContextLoader - Error initializing the application: Error creating bean with name 'pluginManager' defined in ServletContext resource [/WEB-INF/applicationContext.xml]: Invocation of init method failed; nested exception is org.codehaus.groovy.grails.exceptions.GrailsDomainException: Property [children] in class [class test.TreeNode] is a bidirectional one-to-many with two possible properties on the inverse side. Either name one of the properties on other side of the relationship [treeNode] or use the 'mappedBy' static to define the property that the relationship is mapped with. Example: static mappedBy = [children:'myprop']
Message: Error creating bean with name 'pluginManager' defined in ServletContext resource [/WEB-INF/applicationContext.xml]: Invocation of init method failed; nested exception is org.codehaus.groovy.grails.exceptions.GrailsDomainException: Property [children] in class [class test.TreeNode] is a bidirectional one-to-many with two possible properties on the inverse side. Either name one of the properties on other side of the relationship [treeNode] or use the 'mappedBy' static to define the property that the relationship is mapped with. Example: static mappedBy = [children:'myprop']
Line | Method
->> 334 | innerRun in java.util.concurrent.FutureTask$Sync
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
| 166 | run in java.util.concurrent.FutureTask
| 1145 | runWorker in java.util.concurrent.ThreadPoolExecutor
| 615 | run in java.util.concurrent.ThreadPoolExecutor$Worker
^ 722 | run . . . in java.lang.Thread
Caused by GrailsDomainException: Property [children] in class [class test.TreeNode] is a bidirectional one-to-many with two possible properties on the inverse side. Either name one of the properties on other side of the relationship [treeNode] or use the 'mappedBy' static to define the property that the relationship is mapped with. Example: static mappedBy = [children:'myprop']
->> 334 | innerRun in java.util.concurrent.FutureTask$Sync
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
| 166 | run in java.util.concurrent.FutureTask
| 1145 | runWorker in java.util.concurrent.ThreadPoolExecutor
| 615 | run in java.util.concurrent.ThreadPoolExecutor$Worker
^ 722 | run . . . in java.lang.Thread