I am trying to get the following Cypher query written out in GraphClient:
START agency=node(12345)
MATCH agency
-[:AGENCY_HAS_PEOPLE]-()
-[:AGENCY_HAS_PERSON]-person
,person-[?:PERSON_IS_CARER]-carer
,person-[?:PERSON_IS_CLIENT]-client
WHERE (person.UniqueId! = 18989)
RETURN person, carer is not null as IsCarer, client is not null as IsClient
The query works fine in the console and returns the results I expect:
person IsCarer IsClient
Node(1545421) True False
When I try to write that query using Neo4jClient, it throws the following exception.
Expression of type System.Linq.Expressions.LogicalBinaryExpression is not supported.
It is mainly due to the expression in the return statement:
.Start(...)
.Match(...)
.Where(...)
.Return((person, client, carer) => new
{
Person = person.As<Person>(),
IsClient = client != null
IsCarer = carer != null
});
Is anyone already working on a solution for this?
Is there a workaround for it?
Is there any other way to write this query to get the same result?
If I were to implement a solution for this, is there anything related to the internals of Neo4jClient (limitation, pitfalls) that I should know before I begin?
Thanks..
It's a bug in https://github.com/Readify/Neo4jClient/blob/master/Neo4jClient/Cypher/CypherReturnExpressionBuilder.cs
Fork the project
Clone it locally
Write a failing test that demonstrates the problem, in https://github.com/Readify/Neo4jClient/blob/master/Test/Cypher/CypherFluentQueryReturnTests.cs
Fix the issue
Commit and push your fix
Open a pull request
When I'm happy with the quality of the solution, I'll accept and merge the pull request. The fix will then be published to NuGet within a few minutes.
Related
I am creating a service that aggregates data and will need to be able to read any unknown JSON document. I have the pipeline defined as follows:
private def pipeline = (
addHeader("Accept", "application/json")
~> sendReceive
~> unmarshal[JsObject] // Need this to work for JsObject or JsArray //
~> recover
)
This will work with a JsObject but not a JsArray. If I change it to a JsArray then it will not (of course) work with a JsObject. My recover method returns a JsObject.
I would love to be able to define this as a JsValue or enforce a Root format, but for JsValue I get the following compiler error:
could not find implicit value for evidence parameter of type spray.httpx.unmarshalling.FromResponseUnmarshaller[spray.json.JsValue]
And Root Formats also error.
I am not sure how to accomplish what I need, any help would be appreciated.
Use Either, Eric! :) If the response will be either JsObject or JsArray then Either is good solution.
private def pipeline =
addHeader("Accept", "application/json")
~> sendReceive
~> unmarshal[Either[JsObject, JsArray]]
~> recover
However, beware that unmarshal[Either[JsObject, JsArray]] tries to parse response as JsObject first and if it fails, tries to parse it as JsArray. This may lead some performance issues.
After reviewing #Mustafa's answer I created the following to avoid the potential performance hit. In the end, I really only need a JSON AST to pass on.
In the most simple terms, I simply created a function to handle it:
def unmarshalJSON(httpResponse: HttpResponse): JsValue = {
httpResponse.entity.asString.parseJson
}
and altered below:
private def pipeline = {
addHeader("Accept", "application/json")
~> sendReceive
~> unmarshalJSON
~> recover
}
I would of course want to beef this up a bit for production level code, but this could be another alternative and allows me to return a JsValue. #Mustafa I would be interested to hear your thoughts.
I am implementing traversal framework using neo4j java-rest-binding project.
Code is as follows:
RestAPI db = new RestAPIFacade("http://localhost:7474/db/data");
RestNode n21 = db.getNodeById(21);
Map<String,Object> traversalDesc = new HashMap<String, Object>();
traversalDesc.put("order", "breadth_first");
traversalDesc.put("uniqueness", "node_global");
traversalDesc.put("uniqueness", "relationship_global");
traversalDesc.put("returnType", "fullpath");
traversalDesc.put("max_depth", 2);
RestTraverser traverser = db.traverse(n21, traversalDesc);
Iterable<Node> nodes = traverser.nodes();
System.out.println("All Nodes:"); // First Task
for(Node n:nodes){
System.out.println(n.getId());
}
Iterable<Relationship> rels = traverser.relationships();
System.out.println("All Relations:"); // Second Task
for(Relationship r:rels){
System.out.println(r.getId());
}
Iterator<Path> paths = traverser.iterator(); // Third Task
while(paths.hasNext()){
System.out.println(paths.next());
}
I need to do 3 tasks as commented in the code:
Print all the node IDs related to node no. 21
Print all the relation IDs related to node no. 21
Traverse all the paths related to node no. 21
Tasks 1 & 2 are working fine.
But when I try to do traverser.iterator() in 3rd task it throws an Exception saying:
java.lang.IllegalAccessError: tried to access class org.neo4j.helpers.collection.WrappingResourceIterator from class org.neo4j.rest.graphdb.traversal.RestTraverser
Can anyone please check why this is happening or if I am doing wrong then what is the right method to do it.
Thanks in Advance.
I don't believe using the Neo4j Traversal Framework via the REST DB binding is properly supported, nor is it advisable. If you traverse via REST, each node and each relationship will be retrieved over the network as the traversal proceeds, incurring a tremendous overhead for the traversal.
Edit: The above is not true, the REST traverser is smarter than I thought.
In general, it will be faster to use Cypher, and access the Neo4j Server using JDBC. Read more about JDBC here: https://github.com/neo4j-contrib/neo4j-jdbc
If you really want to use the Traversal Framework, you should use Server Extensions, which allow you to design a traversal to run on the server itself, and then only move the result of the traversal over the network. Read more about server extensions here: http://docs.neo4j.org/chunked/stable/server-unmanaged-extensions.html
I am trying to filter data from a table using sql as follows:
$select= new \Zend\Db\Sql\Select ;
$select->from('questions');
$select->where(array('questions.id'=>$value));
$select->columns(array('user_id','description'));
$select->join('users', "users.id = questions.user_id", array('username','password'), 'left');
echo $select->getSqlString();
$resultSet = $this->tableGateway->selectWith($select);
return $resultSet;
Without the $select->where(array('questions.id'=>$value)); the query executes okay and i can get all database values. Otherwise if i add the statement i get this error:
Attempting to quote a value without specific driver level support
can introduce security vulnerabilities in a production environment.
How can i rectify this for the where clause to work?
You'll probably find that it's echoing the SQL string which is generating that error. Assuming you only did that for debugging, removing that line should fix it. Alternatively you can pass the platform object to the function with something like:
echo $select->getSqlString($this->tableGateway->getAdapter()->getPlatform());
In a controller I have this finder
User.findByEmail('test#test.com')
And works.
Works even if I write
User.findByEmail(null)
But if i write
User.findByEmail(session.email)
and session.email is not defined (ergo is null) it throw exception
groovy.lang.MissingMethodException: No signature of method: myapp.User.findByEmail() is applicable for argument types: () values: []
Is this behavior right?
If i evaluate "session.email" it give me null so I think it must work as it do when I write
User.findByEmail(null)
Even more strange....
If I run this code in groovy console:
import myapp.User
User.findByEmail(null)
It return a user that has null email but if I run the same code a second time it return
groovy.lang.MissingMethodException: No signature of method: myapp.User.findByEmail() is applicable for argument types: () values: []
You can't use standard findBySomething dynamic finders to search for null values, you need to use the findBySomethingIsNull version instead. Try
def user = (session.email ? User.findByEmail(session.email)
: User.findByEmailIsNull())
Note that even if User.findByEmail(null) worked correctly every time, it would not necessarily give you the correct results on all databases as a findBySomething(null) would translate to
WHERE something = null
in the underlying SQL query, and according to the SQL spec null is not equal to anything else (not even to null). You have to use something is null in SQL to match null values, which is what findBySomethingIsNull() translates to.
You could write a static utility method in the User class to gather this check into one place
public static User byOptEmail(val) {
if(val == null) {
return User.findByEmailIsNull()
}
User.findByEmail(val)
}
and then use User.byOptEmail(session.email) in your controllers.
Jeff Brown from grails nabble forum has identified my problem. It's a GORM bug. see jira
More info on this thread
This jira too
I tried with debugger and it looks it should be working, as you write. Maybe the groovy itself is a little bit confused here, try to help it this way:
User.findByEmail( session['email'] )
I am using the findAll() SQL-like method:
MyDomainClass.findAll("firstname='George' and lastname='kuo' and username='kjlop'"),
but I have got problem:
when value starts with number(for example,when age='2poj') it throws an exception
I use grails 1.3.2 and gorm-hbase 0.2.4 plugin and in my domain classes fields have String type.
Here is the Stack Trace:
expecting token in range: '0'..'9', found 'p'
at org.grails.hbase.ghql.LexerRules.nextToken(LexerRules.java:125)
at org.grails.hbase.finders.QueryStringTokenizer.tokenize(QueryStringTokenizer.groovy:59)
at org.grails.hbase.finders.TokenizerStrategy$tokenize.call(Unknown Source)
//---------
I wonder is there any way in groovy change findAll() method work ?
If anybody know solution please help.
Thanks in advance.
You should be able to run a dynamic finder method on the domain object to achieve what you need.
Example:
MyDomainClass.findAllByFirstnameAndAge('Dan', 25)
This works for all data types and enums.
You can try like the Grails example:
MyDomainClass.findAll("from DomainTable as b where b.firstname=:firstname and b.age=:age", [firstname:'Dan Brown', age: 25]
Notice: I don't know if you mistype it, but '25' is a string, so that it can't be age='25'
EDIT:
I don't know how this doesn't work, but in case you want to find with multiple properties, you should use createCriteria().
def c = MyDomainClass.createCriteria()
def results = c.list {
like("firstName", "George%")
like("age", "25");
}
EDIT2: Sorry, createCriteria is not supported by hbase plugin. Based on your condition, I think it's suitable to try DynamicFinderFilter (with approriate import).
// all books written by Dan Brown or J K Rowling
DynamicFinderFilter filterList = new FinderFilterList(Operator.OR)
DynamicFinderFilter filter1 = new Filter('author', 'Dan Brown')
filterList.addFilter(filter1)
DynamicFinderFilter filter2 = new Filter('author', 'J K Rowling')
filterList.addFilter(filter12)
results = Book.findAll(filterList)
The complete example can be find in the plugin page.