Gremlin: The provided traverser does not map to a value - database

g.V()
.has('atom', '_value', 'red').fold()
.coalesce(unfold(), addV('atom').property('_value', 'red')).as('atom')
.out('view').has('view', '_name', 'color').fold()
.coalesce(unfold(), addE('view').from('atom').to(addV('view').property('_name', 'color')))
Gives me an error:
The provided traverser does not map to a value: []->[SelectOneStep(last,atom)] (597)
What does it mean?

Adding to this in case someone else comes across this.
This specific error occurs when you use the id as a string in from() instead of the vertex object.
To see what I mean, as a simple test run the following gremlin query:
g.addE('view').from('atom').to(addV('view').property('_name', 'color'))
then run this query:
g.addE('view').from(V('atom')).to(addV('view').property('_name', 'color'))
The first query will give you the error stated above, the second one will not.

So it looks like when as() is followed by fold() it deletes the variable set in the as() step. I used aggregate() instead as follows:
g.V()
.has('atom', '_value', 'red')
.fold().coalesce(
unfold(),
addV('atom').property('_value', 'red')
)
.aggregate('atom')
.out('view').has('view', '_name', 'color')
.fold().coalesce(
unfold(),
addE('view')
.from(select('atom').unfold())
.to(addV('view').property('_name', 'color'))
.inV()
)

The as() step is what is known as a reducing barrier step. With reducing barrier steps any path history of a query (such as applying a label via as()) is lost. In reducing barrier steps many paths are reduced down to a single path. After that step there would be no way to know which of the many original labeled vertices would be the correct one to retrieve.

Related

Use content of a tuple as variable session

I extracted from a previous response an Object of tuple with the following regex :
.check(regex(""""idSc":(.{1,8}),"pasTemps":."codePasTemps":(.),"""").ofType[(String,String)].findAll.saveAs ("OBJECTS1"))
So I get my object :
OBJECTS1 -> List((1657751,2), (1658105,2), (4557378,2), (1657750,1), (916,1), (917,2), (1658068,1), (1658069,2), (4557379,2), (1658082,1), (4557367,1), (4557368,1), (1660865,2), (1660866,2), (1658122,1), (921,1), (922,2), (923,2), (1660875,1), (1660876,2), (1660877,2), (1658300,1), (1658301,1), (1658302,1), (1658309,1), (1658310,1), (2996562,1), (4638455,1))
After that I did a Foreach and need to extract every couple to add them in next requests So we tried :
.foreach("${OBJECTS1}", "couple") {
exec(http("request_foreach47"
.get("/ctr/web/api/seriegraph/bydates/${couple(0)}/${couple(1)}/1552863600000/1554191743799")
.headers(headers_27))
}
But I get the message : named 'couple' does not support index access
I also though that to use 2 regex on the couple to extract both part could work but I haven't found any way to use a regex on a session variable. (Even if its not needed for this case but possible im really interessed to learn how as it could be usefull)
If would be really thankfull if you could provided me help. (Im using Gatling 2 but can,'t use a more recent version as its for work and others scripts have been develloped with Gatling2)
each "couple" is a scala tuple which can't be indexed into like a collection. Fortunately the gatling EL has a function that handles tuples.
so instead of
.get("/ctr/web/api/seriegraph/bydates/${couple(0)}/${couple(1)}/1552863600000/1554191743799")
you can use
.get("/ctr/web/api/seriegraph/bydates/${couple._1}/${couple._2}/1552863600000/1554191743799")

Document each element of an array using spring-restdocs

I'm having a response which is an json array. Each element has it's meaning and I would be able to describe it.
My array:
["1525032694","300","true"]
I've found an example in the documentation that describes an array and each element which is the same:
https://docs.spring.io/spring-restdocs/docs/current/reference/html5/#documenting-your-api-request-response-payloads-fields-reusing-field-descriptors
But I would like to know how I can describe each of it as:
current timestamp, seconds to next measurement, should perform fota
My current test:
webTestClient.post().uri("/api//measurement/${SampleData.deviceId}")
.syncBody(SampleData.sampleMeasurement())
.exchange()
.expectStatus()
.isOk
.expectBody()
.consumeWith(document("add-measurement", responseFields(
fieldWithPath("[]")
.description("An array of device settings"))
))
Ok, it turns that be fairly easy:
responseFields(
fieldWithPath("[0]").description("Current timestamp"),
fieldWithPath("[1]").description("Device mode"),
fieldWithPath("[2]").description("Device parameter")
),

SWIFT OS X - multiple statements inside a closure statement, a debugging tool?

I am using the following code to filter a large array:
var arrayOfSelectedRowDetails = self.projectRowDetails.filter(
{ $0.projectNumber == self.projectNumberArray[selectedRow] }
)
Normally the code runs fine and I have no issues. But in one scenario (after I have deleted some management objects from the persistent store) and then rerun the code I am getting a EXC_BAD_ACCESS (code = 1, address=0x0) error at runtime.
I have set a break and stepped through the runtime of this statement. It is a large array built from a core data entity (using a fetch statement) - and therefore takes a long time. When I step through the code over the first dozen or so indexes the code runs ok - when i remove the break and let it run it then presents the error.
Is it possible to println() from within the closure statement to assist with debugging? I have tried a number of different syntaxes and cannot get it to work.
Alternatively, is it possible to set an error capture statement within the closure so that the code ceases through a break or an abort() statement?
Fundamentally i am trying to identify the index of the array at the point that the error occurs so that I can get sufficient information to debug the delete function (which is where I think the error is). I do not seem to be able to ascertain the index from the info available to me when the error occurs.
This is the first time I have tried programming in Swift and making use of closures so I am learning as I go. Apologies if I am asking fundamental questions. I have not been able to find a similar question elsewhere here with an answer that works.
You can set an exception breakpoint in Xcode (for an example see here).
Also, I suggest that you move the access to self.projectNumberArray out of the closure:
let pn = self.projectNumberArray[selectedRow]
var arrayOfSelectedRowDetails = self.projectRowDetails.filter(
{ $0.projectNumber == pn }
)
The change might not solve the issue, but it will at least help the debugging.
Lastly, if you want to print the index, the following approach will probably work:
let pn = self.projectNumberArray[selectedRow]
var index = 0
var arrayOfSelectedRowDetails = self.projectRowDetails.filter(
{ println(index++); return $0.projectNumber == pn }
)

Select random item from an array with certain probabilities and add it to the stage

Its quite a big task but ill try to explain.
I have an array with a list of 200 strings and I want to be able to randomly select one and add it to the stage using code. I have movieclips exported for actionscript with the same class name as the strings in the array. Also, if it is possible, would I be able to select the strings with predictability such as the first has a 0.7 chance the second a 0.1 etc. Here is what i have currently
var nameList:Array=["Jimmy","Bob","Fred"]
var instance:DisplayObject = createRandom(nameList);
addChild(instance);
function createRandom(typeArray:Array):*
{
// Select random String from typeArray.
var selection:String = typeArray[ int(Math.random() * typeArray.length) ];
// Create instance of relevant class.
var Type:Class = getDefinitionByName(selection) as Class;
// Return created instance.
return new Type();
}
All this throws me this error
ReferenceError: Error #1065: Variable [class Jimmy] is not defined.
Ive searched for other threads similar but none combine the three specific tasks of randomisation, predictability and addChild().
I think that you've got two problems: a language problem and a logic problem. In the .fla connected to your code above, in the Library find each symbol representing a name and write into the 'AS linkage' column for that symbol the associated name -- e.g., 'Bob,' 'Fred' -- just the name, no punctuation.
Now getDefinitionByName() will find your 'Class'
If you put a different graphic into each MovieClip -- say, a piece of fruit or a picture of Bob,Jim, Fred -- and run your program you'll get a random something on stage each time.
That should solve your language problem. But the logic problem is a little harder, no?
That's why I pointed you to Mr. Kelly's solution (the first one, which for me is easier to grasp).

Perl -- DBI selectall_arrayref when querying getting Not Hash Reference

I am very new to perl (but from a c# background) and I am trying to move some scripts to a windows box.
Due to some modules not working easily with windows I have changed the way it connects to the DB.
I have an sqlserver DB and I had a loop reading each row in a table, and then within this loop another query was sent to select different info.
I was the error where two statements can't be executed at once within the same connection.
As my connection object is global I couldn't see an easy way round this, so decided to store the first set of data in an array using:
my $query = shift;
my $aryref = $dbh->selectall_arrayref($query) || die "Could not select to array\n";
return($aryref);
(this is in a module file that is called)
I then do a foreach loop (where #$s_study is the $aryref returned above)
foreach my $r_study ( #$s_study ) {
~~~
my $surveyId=$r_study->{surveyid}; <-------error this line
~~~~
};
When I run this I get an error "Not a hash reference". I don't understand?!
Can anyone help!
Bex
You need to provide the { Slice => {} } parameter to selectall_arrayref if you want each row to be stored as a hash:
my $aryref = $dbh->selectall_arrayref($query, { Slice => {} });
By default, it returns a reference to an array containing a reference to an array for each row of data fetched.
$r_study->{surveyid} is a hashref
$r_study->[0] is an arrayref
this is your error.
You should use the second one
If you have a problem with a method, then a good first step is to read the documentation for that method. Here's a link to the documentation for selectall_arrayref. It says:
This utility method combines
"prepare", "execute" and
"fetchall_arrayref" into a single
call. It returns a reference to an
array containing a reference to an
array (or hash, see below) for each
row of data fetched.
So the default behaviour is to return a reference to an array which contains an array reference for each row. That explains your error. You're getting an array reference and you're trying to treat it as a hash reference. I'm not sure that the error could be much clearer.
There is, however, that interesting bit where it says "or hash, see below". Reading on, we find:
You may often want to fetch an array
of rows where each row is stored as a
hash. That can be done simple using:
my $emps = $dbh->selectall_arrayref(
"SELECT ename FROM emp ORDER BY ename",
{ Slice => {} }
);
foreach my $emp ( #$emps ) {
print "Employee: $emp->{ename}\n";
}
So you have two options. Either switch your code to use an array ref rather than a hash ref. Or add the "{ Slice => {} }" option to the call, which will return a hash ref.
The documentation is clear. It's well worth reading it.
When you encounter something like "Not a hash reference" or "Not an array reference" or similar you can always take Data::Dumper to just dump out your variable and you will quickly see what data you are dealing with: arrays of arrayrefs, hashes of something etc.
And concerning reading the data, this { Slice => {} } is most valuable addition.

Resources