ArangoDB异常

Question

在本教程中运行命令时，我注意到不断收到异常，而这些异常似乎不是shell正常操作的一部分。

命令

arangosh [_system]> db._update(doc, { someValue: 42 });

输出

JavaScript exception in file 'c:/Program Files/ArangoDB 2.5.4/share/arangodb/js/
client/modules/org/arangodb/arango-database.js' at 789,11: [ArangoError 1200: pr
econdition failed]

!    throw new ArangoError(requestResult);
!          ^
stacktrace: Error
    at ArangoDatabase._update (c:/Program Files/ArangoDB 2.5.4/share/arangodb/js
/client/modules/org/arangodb/arango-database.js:789:11)

    at <shell command>:1:4

Answer 1

如果您尝试更新已更新的文档的修订版本，则通常会发生这种情况。

例如：

arangosh [_system]> d1 = db.test.save({ value: 1 })
{ 
  "_id" : "test/41839385817", 
  "_rev" : "41839385817", 
  "_key" : "41839385817" 
}

创建新文档。

arangosh [_system]> d2 = db._update(d1, { value: 2 })
{ 
  "_id" : "test/41839385817", 
  "_rev" : "41840762073", 
  "_key" : "41839385817" 
}

如果现在尝试更新文档的原始版本，则会出现错误：

arangosh [_system]> db._update(d1, { value: 3 })
JavaScript exception in file '/usr/local/Cellar/arangodb/HEAD/share/arangodb/js/client/modules/org/arangodb/arango-database.js' at 790,11: [ArangoError 1200: precondition failed]
!    throw new ArangoError(requestResult);
!          ^
stacktrace: Error
    at ArangoDatabase._update (/usr/local/Cellar/arangodb/HEAD/share/arangodb/js/client/modules/org/arangodb/arango-database.js:790:11)
    at <shell command>:1:4

因为该文档的修订版本不再有效。