8

我正在为 neo4j 使用 django 集成，并且在尝试创建节点时得到以下回溯。
我确实安装了 JPype，它可以被导入。

 p = Person.objects.create(first_name='omer', last_name='katz')
Traceback (most recent call last):
  File "<console>", line 1, in <module>
  File "/usr/local/lib/python2.7/dist-packages/django/db/models/manager.py", line 138, in create
    return self.get_query_set().create(**kwargs)
  File "/usr/local/lib/python2.7/dist-packages/Neo4j.py-0.1_SNAPSHOT-py2.7.egg/neo4j/model/django_model/__init__.py", line 362, in create
    obj.save(force_insert=True)
  File "/usr/local/lib/python2.7/dist-packages/django/db/models/base.py", line 460, in save
    self.save_base(using=using, force_insert=force_insert, force_update=force_update)
  File "/usr/local/lib/python2.7/dist-packages/Neo4j.py-0.1_SNAPSHOT-py2.7.egg/neo4j/_util.py", line 47, in __get__
    method, graphdb = self.descr_get(obj, cls)
  File "/usr/local/lib/python2.7/dist-packages/Neo4j.py-0.1_SNAPSHOT-py2.7.egg/neo4j/_util.py", line 41, in descr_get
    graphdb = self.accessor.__get__(obj, cls)
  File "/usr/local/lib/python2.7/dist-packages/Neo4j.py-0.1_SNAPSHOT-py2.7.egg/neo4j/model/django_model/__init__.py", line 58, in __get__
    return DjangoNeo.neo
  File "/usr/local/lib/python2.7/dist-packages/Neo4j.py-0.1_SNAPSHOT-py2.7.egg/neo4j/model/django_model/__init__.py", line 124, in neo
    return self.__setup_neo()
  File "/usr/local/lib/python2.7/dist-packages/Neo4j.py-0.1_SNAPSHOT-py2.7.egg/neo4j/model/django_model/__init__.py", line 136, in __setup_neo
    self.__neo = NeoService(resource_uri, **options)
  File "/usr/local/lib/python2.7/dist-packages/Neo4j.py-0.1_SNAPSHOT-py2.7.egg/neo4j/__init__.py", line 522, in __new__
    neo = core.load_neo(resource_uri, params)
  File "/usr/local/lib/python2.7/dist-packages/Neo4j.py-0.1_SNAPSHOT-py2.7.egg/neo4j/_core.py", line 180, in load_neo
    backend.initialize(**parameters)
  File "/usr/local/lib/python2.7/dist-packages/Neo4j.py-0.1_SNAPSHOT-py2.7.egg/neo4j/_backend/__init__.py", line 61, in initialize
    raise ImportError("No applicable backend found.")
ImportError: No applicable backend found.

编辑：
这里要求的是我的 neo4j 设置：

NEO4J_RESOURCE_URI = '/var/neo4j/neo4django'
# NEO4J_RESOURCE_URI should be the path to where
#    you want to store the Neo4j database.

NEO4J_OPTIONS = {
    # this is optional and can be used to specify
    # extra startup parameters for Neo4j, such as
    # the classpath to load Neo4j from.
}

编辑：
遵循 thobe 的建议后，当我尝试导入自己的模型时，我得到以下信息： 

    ERROR:root:Importing native backends failed.
    Traceback (most recent call last):
      File "/usr/local/lib/python2.7/dist-packages/Neo4j.py-0.1_SNAPSHOT-py2.7.egg/neo4j/_backend/__init__.py", line 51, in initialize
        embedded, remote = implementation.initialize(classpath, params)
      File "/usr/local/lib/python2.7/dist-packages/Neo4j.py-0.1_SNAPSHOT-py2.7.egg/neo4j/_backend/reflection.py", line 44, in initialize
        jvm = jpype.getDefaultJVMPath()
      File "/usr/local/lib/python2.7/dist-packages/jpype/_core.py", line 96, in getDefaultJVMPath
        return _linux.getDefaultJVMPath()
      File "/usr/local/lib/python2.7/dist-packages/jpype/_linux.py", line 36, in getDefaultJVMPath
        jvm = _getJVMFromJavaHome()
      File "/usr/local/lib/python2.7/dist-packages/jpype/_linux.py", line 55, in _getJVMFromJavaHome
        if os.path.exists(java_home+"/bin/javac") :
    TypeError: unsupported operand type(s) for +: 'NoneType' and 'str'
    ERROR:root:Importing native backends failed.
    Traceback (most recent call last):
      FERROR:root:Importing native backends failed.
    Traceback (most recent call last):
      File "/usr/local/lib/python2.7/dist-packages/Neo4j.py-0.1_SNAPSHOT-py2.7.egg/neo4j/_backend/__init__.py", line 51, in initialize
        embedded, remote = implementation.initialize(classpath, params)
      File "/usr/local/lib/python2.7/dist-packages/Neo4j.py-0.1_SNAPSHOT-py2.7.egg/neo4j/_backend/reflection.py", line 44, in initialize
        jvm = jpype.getDefaultJVMPath()
      File "/usr/local/lib/python2.7/dist-packages/jpype/_core.py", line 96, in getDefaultJVMPath
        return _linux.getDefaultJVMPath()
      File "/usr/local/lib/python2.7/dist-packages/jpype/_linux.py", line 36, in getDefaultJVMPath
        jvm = _getJVMFromJavaHome()
      File "/usr/local/lib/python2.7/dist-packages/jpype/_linux.py", line 55, in _getJVMFromJavaHome
        if os.path.exists(java_home+"/bin/javac") :
    TypeError: unsupported operand type(s) for +: 'NoneType' and 'str'
    ERROR:root:Importing native backends failed.
    Traceback (most recent call last):
      File "/usr/local/lib/python2.7/dist-packages/Neo4j.py-0.1_SNAPSHOT-py2.7.egg/neo4j/_backend/__init__.py", line 51, in initialize
        embedded, remote = implementation.initialize(classpath, params)
      File "/usr/local/lib/python2.7/dist-packages/Neo4j.py-0.1_SNAPSHOT-py2.7.egg/neo4j/_backend/reflection.py", line 44, in initialize
        jvm = jpype.getDefaultJVMPath()
      File "/usr/local/lib/python2.7/dist-packages/jpype/_core.py", line 96, in getDefaultJVMPath
        return _linux.getDefaultJVMPath()
      File "/usr/local/lib/python2.7/dist-packages/jpype/_linux.py", line 36, in getDefaultJVMPath
        jvm = _getJVMFromJavaHome()
      File "/usr/local/lib/python2.7/dist-packages/jpype/_linux.py", line 55, in _getJVMFromJavaHome
        if os.path.exists(java_home+"/bin/javac") :
    TypeError: unsupported operand type(s) for +: 'NoneType' and 'str'
    ERROR:root:Importing native backends failed.
    Traceback (most recent call last):
      File "/usr/local/lib/python2.7/dist-packages/Neo4j.py-0.1_SNAPSHOT-py2.7.egg/neo4j/_backend/__init__.py", line 51, in initialize
        embedded, remote = implementation.initialize(classpath, params)
      File "/usr/local/lib/python2.7/dist-packages/Neo4j.py-0.1_SNAPSHOT-py2.7.egg/neo4j/_backend/reflection.py", line 44, in initialize
        jvm = jpype.getDefaultJVMPath()
      File "/usr/local/lib/python2.7/dist-packages/jpype/_core.py", line 96, in getDefaultJVMPath
        return _linux.getDefaultJVMPath()
      File "/usr/local/lib/python2.7/dist-packages/jpype/_linux.py", line 36, in getDefaultJVMPath
        jvm = _getJVMFromJavaHome()
      File "/usr/local/lib/python2.7/dist-packages/jpype/_linux.py", line 55, in _getJVMFromJavaHome
        if os.path.exists(java_home+"/bin/javac") :
    TypeError: unsupported operand type(s) for +: 'NoneType' and 'str'
    ERROR:root:Importing native backends failed.
    Traceback (most recent call last):
      File "/usr/local/lib/python2.7/dist-packages/Neo4j.py-0.1_SNAPSHOT-py2.7.egg/neo4j/_backend/__init__.py", line 51, in initialize
        embedded, remote = implementation.initialize(classpath, params)
      File "/usr/local/lib/python2.7/dist-packages/Neo4j.py-0.1_SNAPSHOT-py2.7.egg/neo4j/_backend/reflection.py", line 44, in initialize
        jvm = jpype.getDefaultJVMPath()
      File "/usr/local/lib/python2.7/dist-packages/jpype/_core.py", line 96, in getDefaultJVMPath
        return _linux.getDefaultJVMPath()
      File "/usr/local/lib/python2.7/dist-packages/jpype/_linux.py", line 36, in getDefaultJVMPath
        jvm = _getJVMFromJavaHome()
      File "/usr/local/lib/python2.7/dist-packages/jpype/_linux.py", line 55, in _getJVMFromJavaHome
        if os.path.exists(java_home+"/bin/javac") :
    TypeError: unsupported operand type(s) for +: 'NoneType' and 'str'
    ERROR:root:Importing native backends failed.
    Traceback (most recent call last):
      File "/usr/local/lib/python2.7/dist-packages/Neo4j.py-0.1_SNAPSHOT-py2.7.egg/neo4j/_backend/__init__.py", line 51, in initialize
        embedded, remote = implementation.initialize(classpath, params)
      File "/usr/local/lib/python2.7/dist-packages/Neo4j.py-0.1_SNAPSHOT-py2.7.egg/neo4j/_backend/reflection.py", line 44, in initialize
        jvm = jpype.getDefaultJVMPath()
      File "/usr/local/lib/python2.7/dist-packages/jpype/_core.py", line 96, in getDefaultJVMPath
        return _linux.getDefaultJVMPath()
      File "/usr/local/lib/python2.7/dist-packages/jpype/_linux.py", line 36, in getDefaultJVMPath
        jvm = _getJVMFromJavaHome()
      File "/usr/local/lib/python2.7/dist-packages/jpype/_linux.py", line 55, in _getJVMFromJavaHome
        if os.path.exists(java_home+"/bin/javac") :
    TypeError: unsupported operand type(s) for +: 'NoneType' and 'str'

ile "/usr/local/lib/python2.7/dist-packages/Neo4j.py-0.1_SNAPSHOT-py2.7.egg/neo4j/_backend/__init__.py", line 51, in initialize
    embedded, remote = implementation.initialize(classpath, params)
  File "/usr/local/lib/python2.7/dist-packages/Neo4j.py-0.1_SNAPSHOT-py2.7.egg/neo4j/_backend/reflection.py", line 44, in initialize
    jvm = jpype.getDefaultJVMPath()
  File "/usr/local/lib/python2.7/dist-packages/jpype/_core.py", line 96, in getDefaultJVMPath
    return _linux.getDefaultJVMPath()
  File "/usr/local/lib/python2.7/dist-packages/jpype/_linux.py", line 36, in getDefaultJVMPath
    jvm = _getJVMFromJavaHome()
  File "/usr/local/lib/python2.7/dist-packages/jpype/_linux.py", line 55, in _getJVMFromJavaHome
    if os.path.exists(java_home+"/bin/javac") :
TypeError: unsupported operand type(s) for +: 'NoneType' and 'str'
ERROR:root:Importing native backends failed.
Traceback (most recent call last):
  File "/usr/local/lib/python2.7/dist-packages/Neo4j.py-0.1_SNAPSHOT-py2.7.egg/neo4j/_backend/__init__.py", line 51, in initialize
    embedded, remote = implementation.initialize(classpath, params)
  File "/usr/local/lib/python2.7/dist-packages/Neo4j.py-0.1_SNAPSHOT-py2.7.egg/neo4j/_backend/reflection.py", line 44, in initialize
    jvm = jpype.getDefaultJVMPath()
  File "/usr/local/lib/python2.7/dist-packages/jpype/_core.py", line 96, in getDefaultJVMPath
    return _linux.getDefaultJVMPath()
  File "/usr/local/lib/python2.7/dist-packages/jpype/_linux.py", line 36, in getDefaultJVMPath
    jvm = _getJVMFromJavaHome()
  File "/usr/local/lib/python2.7/dist-packages/jpype/_linux.py", line 55, in _getJVMFromJavaHome
    if os.path.exists(java_home+"/bin/javac") :
TypeError: unsupported operand type(s) for +: 'NoneType' and 'str'
ERROR:root:Importing native backends failed.
Traceback (most recent call last):
  File "/usr/local/lib/python2.7/dist-packages/Neo4j.py-0.1_SNAPSHOT-py2.7.egg/neo4j/_backend/__init__.py", line 51, in initialize
    embedded, remote = implementation.initialize(classpath, params)
  File "/usr/local/lib/python2.7/dist-packages/Neo4j.py-0.1_SNAPSHOT-py2.7.egg/neo4j/_backend/reflection.py", line 44, in initialize
    jvm = jpype.getDefaultJVMPath()
  File "/usr/local/lib/python2.7/dist-packages/jpype/_core.py", line 96, in getDefaultJVMPath
    return _linux.getDefaultJVMPath()
  File "/usr/local/lib/python2.7/dist-packages/jpype/_linux.py", line 36, in getDefaultJVMPath
    jvm = _getJVMFromJavaHome()
  File "/usr/local/lib/python2.7/dist-packages/jpype/_linux.py", line 55, in _getJVMFromJavaHome
    if os.path.exists(java_home+"/bin/javac") :
TypeError: unsupported operand type(s) for +: 'NoneType' and 'str'
ERROR:root:Importing native backends failed.
Traceback (most recent call last):
  File "/usr/local/lib/python2.7/dist-packages/Neo4j.py-0.1_SNAPSHOT-py2.7.egg/neo4j/_backend/__init__.py", line 51, in initialize
    embedded, remote = implementation.initialize(classpath, params)
  File "/usr/local/lib/python2.7/dist-packages/Neo4j.py-0.1_SNAPSHOT-py2.7.egg/neo4j/_backend/reflection.py", line 44, in initialize
    jvm = jpype.getDefaultJVMPath()
  File "/usr/local/lib/python2.7/dist-packages/jpype/_core.py", line 96, in getDefaultJVMPath
    return _linux.getDefaultJVMPath()
  File "/usr/local/lib/python2.7/dist-packages/jpype/_linux.py", line 36, in getDefaultJVMPath
    jvm = _getJVMFromJavaHome()
  File "/usr/local/lib/python2.7/dist-packages/jpype/_linux.py", line 55, in _getJVMFromJavaHome
    if os.path.exists(java_home+"/bin/javac") :
TypeError: unsupported operand type(s) for +: 'NoneType' and 'str'
4

3 回答 3

2

您可以通过将其添加到 NEO4J_OPTIONS 来获取有关为什么找不到后端的更多详细信息：

NEO4J_OPTIONS = {
    log: True,
}

该日志记录的输出将更容易诊断实际问题并提出修复建议。

于 2011-06-27T12:43:28.530 回答
1

你的 settings.py 看起来不错..

您是否安装了 java SDK 并将 JAVA_HOME 环境变量设置为您的 JDK？（java JRE 还不够）

来自 Neo4j.py 文档：

在某些情况下，JPype 编译过程可能不会与适当的 JNI 标头链接，从而导致编译错误。首先要注意的是，JPype 需要来自 JDK 的 JNI 标头才能构建，在构建 JPype 时仅安装 JRE 是不够的。如果在构建 JPype 时未设置 JAVA_HOME 环境变量，则 JPype 的构建脚本 (setup.py) 可能无法找到相应的 JNI 标头。如果您使用 sudo python setup.py install 构建 JPype，您可能不会将 JAVA_HOME 环境变量继承到 sudo 环境中，一个简单的解决方法是在安装之前运行 python setup.py bdist。

于 2011-06-22T20:13:42.690 回答
1

我遇到了同样的问题。无论我做了什么（在 Debian 上），Python 都找不到 JAVA_HOME 环境变量。修复它的最简单方法，我认为你可以在 Django 中的某个地方添加它，是添加这些行 -

java_home = os.getenv("JAVA_HOME")
if(java_home == None):
    os.environ["JAVA_HOME"] = "/usr/lib/jvm/java-6-openjdk"

其中路径是您要使用的 JDK 的位置（它后面应该有文件夹 /bin 以及 java 和 javac 程序）

我还尝试将位置添加到 /etc/bash.bashrc。这对我不起作用，但可能对你有用。

JAVA_HOME=/usr/lib/jvm/java-6-openjdk
export JAVA_HOME
PATH=$PATH:$JAVA_HOME/bin
export PATH

无论如何，这应该让你朝着正确的方向开始。但是现在我有另一个相关的问题，我被困了一个星期没有答案:(

于 2011-07-27T06:11:28.187 回答