Limit the number of edges can be added to a vertex in orientDB

Question

I am using orientDB 2.2.7 via Java API and have created the following vertexes:

Vertex Car
Vertex Driver
Edge Co-Owner

For each car it can only get a maximum of five owners, I have managed to do that by code in a trivial way, my question is there any mechanism in orientDB that can limit the number of edges of type co-owner can be added to vertex car?

Answer 1

I made this little test case using Dynamic Hooks, I hope is similar to yours.

create class Car extends V
create class Driver extends V
create class CoOwner extends E,OTriggered

ALTER CLASS CoOwner CUSTOM onBeforeCreate=createOwner

create property Car.ID string
create property Car.Model string
create property Car.Color string

create property Driver.Name string
create property Driver.Surname string
create property Driver.CF string

create index Car.ID UNIQUE_HASH_INDEX
create index Driver.CF UNIQUE_HASH_INDEX

---

create vertex Car set ID="AA666ZZ", Model="Fiat Panda", Color="Black"
create vertex Car set ID="BB222ZZ", Model="Ferrari 458 Italia", Color="Red"
create vertex Car set ID="CC954ZZ", Model="AlfaRomeo Giulietta", Color="Blue"

create vertex Driver set Name="Pino", Surname="Pasticcino", CF="PNOPSC1234567890"
create vertex Driver set Name="Giannaldo", Surname="Pippi", CF="GNLPIP1234567890"
create vertex Driver set Name="Pierromeo", Surname="Pasticcino", CF="PRMPSC1234567890"
create vertex Driver set Name="Adalbrigo", Surname="Brighi", CF="ALRBGH1234567890"
create vertex Driver set Name="Renfrancesco", Surname="Raldi", CF="RFCRLD1234567890"
create vertex Driver set Name="Caldanzio", Surname="Freddi", CF="CDZFRD1234567890"
create vertex Driver set Name="Roberdrigo", Surname="Brighi", CF="RBRBGH1234567890"
create vertex Driver set Name="Gorzorg", Surname="Il Distruggitore", CF="GRZIDG1234567890"

---

then you need to create a JS function with the following code:

var MAX_EDGES = 5;
var CUR_EDGES = doc.field('out').field('out_CoOwner').size();

print('\n--------------------------------------------------------------------');
print('\n\nMax Edges: ' + MAX_EDGES);
print('\nCoOwner edges: ' + CUR_EDGES);

if ( CUR_EDGES > MAX_EDGES ){
  throw new java.lang.RuntimeException("Maximum number of edges reached.");
}
else {
  print('OK!');
}

---

then you can test it by trying to add 6 edges.

create edge CoOwner from (select from Car where ID = "AA666ZZ") to (select from Driver where CF = "PNOPSC1234567890")
create edge CoOwner from (select from Car where ID = "AA666ZZ") to (select from Driver where CF = "RFCRLD1234567890")
create edge CoOwner from (select from Car where ID = "AA666ZZ") to (select from Driver where CF = "GNLPIP1234567890")
create edge CoOwner from (select from Car where ID = "AA666ZZ") to (select from Driver where CF = "CDZFRD1234567890")
create edge CoOwner from (select from Car where ID = "AA666ZZ") to (select from Driver where CF = "PRMPSC1234567890")
create edge CoOwner from (select from Car where ID = "AA666ZZ") to (select from Driver where CF = "RBRBGH1234567890")

console log:

--------------------------------------------------------------------


Max Edges: 5

CoOwner edges: 1
OK!

--------------------------------------------------------------------


Max Edges: 5

CoOwner edges: 2
OK!

--------------------------------------------------------------------


Max Edges: 5

CoOwner edges: 3
OK!

--------------------------------------------------------------------


Max Edges: 5

CoOwner edges: 4
OK!

--------------------------------------------------------------------


Max Edges: 5

CoOwner edges: 5
OK!

--------------------------------------------------------------------


Max Edges: 5

CoOwner edges: 6

2016-08-22 17:46:45:292 SEVER Internal server error:
com.orientechnologies.orient.core.command.script.OCommandScriptException: Error on parsing script at position #2: Error on execution of the script
Script: createOwner
-------^
    DB name="stack39062533"
--> javax.script.ScriptException: java.lang.RuntimeException: Maximum number of edges reached. in <eval> at line number 10 at column number 2
--> <eval>:10:2 java.lang.RuntimeException: Maximum number of edges reached.
--> java.lang.RuntimeException: Maximum number of edges reached. [ONetworkProtocolHttpDb]