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我想使用服務器部分的Grails框架和Neo4j數據庫進行存儲的Web應用程序。我在Grails網站上發現了Neo4j GORM插件，但不幸的是經過多次嘗試後，我無法正常工作。如果我解決了一個錯誤，我得到更多，我甚至不能設置一個基本的應用程序工作。所以我想寫我自己的代碼來處理CRUD操作。我想重寫域類的默認CRUD操作。例如，當我保存一個Person實體時，我會使用Neo4j數據庫提供的REST API來存儲實體等。這是一個可接受的解決方案嗎？如果是，那麼我應該如何着手重寫域類的CRUD方法？不使用Neo4j GORM插件的Grails應用程序的Neo4j數據庫
問題我使用GORM插件：我遵循文檔中描述的步驟：http://projects.spring.io/grails-data-mapping/neo4j/manual/guide/gettingStarted.html。我創建了一個簡單的Grails網絡應用程序，包括Neo4j-GORM插件依賴項。應用程序已啓動。 
如果我嘗試訪問「org.grails.datastore.gorm.neo4j.Neo4jController」我得到一些奇怪的錯誤： 
下面是我在控制檯得到錯誤：
015-01-04 14:11:22,460 [http-bio-8080-exec-2] ERROR errors.GrailsExceptionResolver - NullPointerException occurred when processing request: [GET] /ANewHope/neo4j/node
Cannot invoke method getNodeById() on null object. Stacktrace follows:
Message: Cannot invoke method getNodeById() on null object
Line | Method
->> 30 | doCall in org.grails.datastore.gorm.neo4j.Neo4jController$_closure2
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
| 198 | doFilter in grails.plugin.cache.web.filter.PageFragmentCachingFilter
| 63 | doFilter in grails.plugin.cache.web.filter.AbstractFilter
| 1145 | runWorker in java.util.concurrent.ThreadPoolExecutor
| 615 | run . . . in java.util.concurrent.ThreadPoolExecutor$Worker
^ 745 | run in java.lang.Thread
這裏是我的BuildConfig.groovy：
grails.servlet.version = "3.0" // Change depending on target container compliance (2.5 or 3.0)
grails.project.class.dir = "target/classes"
grails.project.test.class.dir = "target/test-classes"
grails.project.test.reports.dir = "target/test-reports"
grails.project.work.dir = "target/work"
grails.project.target.level = 1.6
grails.project.source.level = 1.6
//grails.project.war.file = "target/${appName}-${appVersion}.war"
grails.project.fork = [
// configure settings for compilation JVM, note that if you alter the Groovy version forked compilation is required
// compile: [maxMemory: 256, minMemory: 64, debug: false, maxPerm: 256, daemon:true],
// configure settings for the test-app JVM, uses the daemon by default
test: [maxMemory: 768, minMemory: 64, debug: false, maxPerm: 256, daemon:true],
// configure settings for the run-app JVM
run: [maxMemory: 768, minMemory: 64, debug: false, maxPerm: 256, forkReserve:false],
// configure settings for the run-war JVM
war: [maxMemory: 768, minMemory: 64, debug: false, maxPerm: 256, forkReserve:false],
// configure settings for the Console UI JVM
console: [maxMemory: 768, minMemory: 64, debug: false, maxPerm: 256]
]
grails.project.dependency.resolver = "maven" // or ivy
grails.project.dependency.resolution = {
// inherit Grails' default dependencies
inherits("global") {
// specify dependency exclusions here; for example, uncomment this to disable ehcache:
// excludes 'ehcache'
}
log "error" // log level of Ivy resolver, either 'error', 'warn', 'info', 'debug' or 'verbose'
checksums true // Whether to verify checksums on resolve
legacyResolve false // whether to do a secondary resolve on plugin installation, not advised and here for backwards compatibility
repositories {
inherits true // Whether to inherit repository definitions from plugins
grailsPlugins()
grailsHome()
mavenLocal()
grailsCentral()
mavenCentral()
// uncomment these (or add new ones) to enable remote dependency resolution from public Maven repositories
//mavenRepo "http://repository.codehaus.org"
//mavenRepo "http://download.java.net/maven/2/"
//mavenRepo "http://repository.jboss.com/maven2/"
mavenRepo 'http://m2.neo4j.org/releases'
}
dependencies {
// specify dependencies here under either 'build', 'compile', 'runtime', 'test' or 'provided' scopes e.g.
// runtime 'mysql:mysql-connector-java:5.1.29'
// runtime 'org.postgresql:postgresql:9.3-1101-jdbc41'
test "org.grails:grails-datastore-test-support:1.0.2-grails-2.4"
}
plugins {
// plugins for the build system only
build ":tomcat:7.0.55"
// plugins for the compile step
compile ":neo4j:2.0.0-M02"
compile ":scaffolding:2.1.2"
compile ':cache:1.1.8'
compile ":asset-pipeline:1.9.9"
// plugins needed at runtime but not for compilation
// runtime ":hibernate4:4.3.6.1" // or ":hibernate:3.6.10.18"
//runtime ":database-migration:1.4.0"
runtime ":jquery:1.11.1"
// Uncomment these to enable additional asset-pipeline capabilities
//compile ":sass-asset-pipeline:1.9.0"
//compile ":less-asset-pipeline:1.10.0"
//compile ":coffee-asset-pipeline:1.8.0"
//compile ":handlebars-asset-pipeline:1.3.0.3"
}
}
這裏是DataSource.groov Y：
dataSource {
pooled = true
jmxExport = true
driverClassName = "org.h2.Driver"
username = "sa"
password = ""
}
//hibernate {
// cache.use_second_level_cache = true
// cache.use_query_cache = false
//// cache.region.factory_class = 'net.sf.ehcache.hibernate.EhCacheRegionFactory' // Hibernate 3
// cache.region.factory_class = 'org.hibernate.cache.ehcache.EhCacheRegionFactory' // Hibernate 4
// singleSession = true // configure OSIV singleSession mode
// flush.mode = 'manual' // OSIV session flush mode outside of transactional context
//}
//grails {
// neo4j {
// type = "embedded"
// location = "C:\\data\\neo4j"
// params = []
// }
//}
// environment specific settings
environments {
development {
dataSource {
dbCreate = "create-drop" // one of 'create', 'create-drop', 'update', 'validate', ''
url = "jdbc:h2:mem:devDb;MVCC=TRUE;LOCK_TIMEOUT=10000;DB_CLOSE_ON_EXIT=FALSE"
}
}
test {
dataSource {
dbCreate = "update"
url = "jdbc:h2:mem:testDb;MVCC=TRUE;LOCK_TIMEOUT=10000;DB_CLOSE_ON_EXIT=FALSE"
}
}
production {
dataSource {
dbCreate = "update"
url = "jdbc:h2:prodDb;MVCC=TRUE;LOCK_TIMEOUT=10000;DB_CLOSE_ON_EXIT=FALSE"
properties {
// See http://grails.org/doc/latest/guide/conf.html#dataSource for documentation
jmxEnabled = true
initialSize = 5
maxActive = 50
minIdle = 5
maxIdle = 25
maxWait = 10000
maxAge = 10 * 60000
timeBetweenEvictionRunsMillis = 5000
minEvictableIdleTimeMillis = 60000
validationQuery = "SELECT 1"
validationQueryTimeout = 3
validationInterval = 15000
testOnBorrow = true
testWhileIdle = true
testOnReturn = false
jdbcInterceptors = "ConnectionState"
defaultTransactionIsolation = java.sql.Connection.TRANSACTION_READ_COMMITTED
}
}
}
}
在此之後我試圖指定的位置，如文檔中建議，並添加以下到DataSource.groovy的：
grails {
neo4j {
type = "embedded"
location = "C:\\data\\neo4j"
params = []
}
}
的結果是一樣的。嘗試失敗後，我決定嘗試其他解決方案。 我想爲我的學士論文項目使用Neo4j，我的教授建議我將它與Grails一起使用。我喜歡Neo4j和Grails，但不幸的是，當我嘗試將它們一起使用時，我遇到了這個問題。
什麼不適合你？使用GORM插件？作者肯定會喜歡你的反饋。 –