where is the document about gremlin with step?
https://tinkerpop.apache.org/docs/current/reference/#with-step
https://tinkerpop.apache.org/javadocs/current/full/org/apache/tinkerpop/gremlin/process/computer/traversal/step/map/ShortestPath.html
there is no example I can use.
I want to know all with-step option(like ShortestPath.edges-Direction.OUT) for shortestPath().
I found below
g.withComputer().V(xxx).shortestPath().with(ShortestPath.edges, Direction.OUT).with(ShortestPath.distance, 'cost').with(ShortestPath.target, hasId(bbb))
I want to know all option I can use
The with()-step is not really a "step". It is a step modulator. Its context is bound to the step that it is modifying and therefore you won't find "all the with() configurations" in one place. You can only find them in the documentation related to the steps that they modulate. Using shortestPath() as an example, note that if you look at the shortestPath() step documentation all of the options are present.
You may also need to consult the documentation of your graph provider as they may provide their own configuration keys for certain steps which can help optimize or otherwise modify traversal operations.
Related
In argparse you provide help alongside the definition of the argument. This helps keep the doc up-to-date with the args.
Is there an option to do something similar in Hydra? Or some other preferred way for documenting the options, without having to list them manually within the hydra/help message?
Edit: this becomes an even greater problem when using call/instantiate and the config options depend on the code.
Right now we recommend using hydra/help. We do have a feature request, feel free to follow/contribute to the discussions here https://github.com/facebookresearch/hydra/issues/633.
Thanks!
In something like SQL, when I create a table I can create type constraints (String with certain lengths, booleans, etc).
How do I do that in gremlin? I am using a javascript implementation, and I know I can switch to typescript and add a lot of type enforcement on that side, but ideally I would also like to have type constraints on the database side too.
I know I can switch to typescript and add a lot of type enforcement on that side
There is an open issue for Typescript at TINKERPOP-2027 and while there was some activity there, no one has really picked up the work.
I would also like to have type constraints on the database side too.
Constraints in the database are not a feature of TinkerPop. For 3.x we long ago committed to allowing graph providers who implement TinkerPop interfaces to provide their own functionality for doing so. There are a lot of historical reasons for that which I won't bother to detail, but the basic answer to your question is that if you want such functionality you need to choose a graph that has that sort of thing. Perhaps take a look at JanusGraph or DS Graph as both have a fairly robust schema language.
I am trying to add basic read/write authorization in gremlin-server, I want to know if there is a way by which I can identify if this query is read-only query or write query.
There is no API call you can make to determine that, but you can get inspiration for how to detect it from ReadOnlyStrategy here. The key is to cycle the Traversal object and look for a Step that implements the Mutating interface. If you find one of those in there, you could classify the traversal as a write query.
Of course, for Gremlin, classifying a query and read or write isn't so binary as it could easily be a mix of read and write. It's also possible that at runtime the write might never execute depending on the flow of the traversal, so it could be "runtime readonly". Hopefully, detecting the Mutating interface is a good-enough solution for you.
I'm not sure where you intend to implement this authorization function but I sense it would be best done as a TraversalStrategy that would then fire on traversal execution. I don't know if that's too late for your authorization process, but it would be the easiest way I can envision. The problem is that if you are accepting scripts then with that approach you could get a partial execution of that script up to the point where authorization was not allowed. If you needed to disallow an entire script based on one write traversal then you might need to look at a custom sandbox. Of course, it is better to avoid scripts altogether and simply use bytecode based requests only. If you are only concerned with bytecode then TraversalStrategy should work pretty well for the authorization use case.
The line: g.V('1').out('knows').hasId('2').hasNext()
This exact line works in the Gremlin console.
I have not read in the documentation that hasNext does not exist in Gremlin.NET. Am I missing something, or is there simply another way to do this in Gremlin.NET?
This method is really missing in Gremlin.Net right now. While this is not explicitly stated in the documentation, the documentation does list all terminal steps implemented by Gremlin.Net:
ITraversal.Next()
ITraversal.NextTraverser()
ITraversal.ToList()
ITraversal.ToSet()
ITraversal.Iterate()
hasNext is also such a terminal step but as you can see it is missing in this list.
The only workaround I can think of for situations like this is to use the count step and then check in your application whether the returned count is greater than zero:
var count = g.V("1").Out("knows").HasId("2").Count().Next();
var exists = count > 0;
In some cases it could also make sense to limit the number of vertices going into the Count step as you aren't interested in the exact count but only want to know whether at least one vertex exists:
g.V("1").Out("knows").HasId("2").Limit<Vertex>(1).Count().Next();
This is also the proposed workaround in the ticket for this feature: TINKERPOP-1921.
It does not exist yet:
https://issues.apache.org/jira/browse/TINKERPOP-1921
The main reason is related to the fact that hasNext() is a Java Iterator semantic that was not applied to .NET. Gremlin Language Variants (GLVs) like .NET are given some latitude in terms of how they interpret the language so as to provide the most at-home feel for developers using it. In other words, if you are using the .NET GLV you shouldn't feel as though you are coding in Java, but should instead feel write at home with the standard .NET semantics.
That said, it could be argued, as it is in the issue I've referenced above, that something like hasNext() is a common form of Gremlin as a query language and should thus be available in all GLVs. So, we will consider those options as we come across them.
For .NET I guess you would try to check Current as discussed here.
Can I know how an experienced OCaml developer debugs his code?
What I am doing is just using Printf.printf. It is too troublesome as I have to comment them all out when I need a clean output.
How should I better control this debugging process? special annotation to switch those logging on or off?
thanks
You can use bolt for this purpose. It's a syntax extension.
Btw. Ocaml has a real debugger.
There is a feature of the OCaml debugger that you may not be aware of which is not commonly found with stateful programming and is called time travel. See section 16.4.4. Basically since all of the information from step to step is kept on the stack, by keeping the changes associated with each step saved during processing, one can move through the changes in time to see the values during that step. Think of it as running the program once logging all of the values at each step into a data store then indexing into that data store based on a step number to see the values at that step.
You can also use ocp-ppx-debug which will add a printf with the good location instead of adding them manually.
https://github.com/OCamlPro-Couderc/ocp-ppx-debug