Help! shortestpath Query Structure?

Users Dgraph
1

Hello forums… thanks for any assistance you could provide.

I am attempting to build a query that produces the shortest path between a specific node Skill S and any other node of a specific type “Resource”. I’d also like to return the SUM(resistance) facet value for any given path: this is the criteria for minimization.

Here’s an example query between two individual nodes. Could anyone please help me to modify the DQL to produce a query that returns the paths between Skill S and any node of type Resource?

{

S as var(func: eq(XID, "Skill/NAICS/523930"))
R1 as var(func: eq(XID, "Resource/bob_smith"))

path as shortest(from: uid(S), to: uid(R1), numpaths: 1) {
  Skill.Skills @facets(resistance)
  Skill.Organizations @facets(resistance)
  Organization.Projects @facets(resistance)
  Project.ProjectRoles @facets(resistance)
  ProjectRole.Resource @facets(resistance)
}

path(func: uid(path)) {
  Name
}

}

2

Are they linked anyway? If so, they should appear in the result. But why so many edges?

3

Thank you for the reply, Michel.

A1: All the links seem to work well and I can execute the query perfectly between individual Skill and Resource nodes (see code block):

{

   S as var(func: eq(XID, "Skill/NAICS/54"))
   R1 as var(func: eq(XID, "Resource/bob/smith"))

   path as shortest(from: uid(S), to: uid(R1), numpaths: 1) {
      Skill.Skills @facets(resistance)
      Skill.Organizations @facets(resistance)
      Skill.Resources @facets(resistance)
      Organization.Projects @facets(resistance)
      Project.ProjectRoles @facets(resistance)
      ProjectRole.Resource @facets(resistance)
    }
  
  path(func: uid(path)) {
   dgraph.type
   Name
   XID
  }
}

A2: I’m traversing across many different types and predicates (see diagram below), though most the edges with resistance are purposefully one-directional.

skillgraph
skillgraph1784×995 102 KB

Here’s my question, now:
I’m attempting to return all Resource (0…N) nodes that can be related to a single Skill node, S. Here’s what I have so far and it’s not working. There’s something about DQL execution or syntax that I’m missing (see code block):

{
  S as var(func: eq(XID, "Skill/NAICS/54"))

var(func: eq(dgraph.type,"Resource")) {
    uid
    path as shortest(from: uid(S), to: uid, numpaths: 1) { 
      Skill.Skills @facets(resistance)
      Skill.Resources @facets(resistance)
      Skill.Organizations @facets(resistance)
      Organization.Projects @facets(resistance)
      Project.ProjectRoles @facets(resistance)
      ProjectRole.Resource @facets(resistance)
    }
    
    path(func: uid(path)) {
     Name
     XID
    } 
  }
}

This query results in an error message: “line 8 column 30: Expecting argument name. Got: lex.Item [11] “(” at 8:30”, which appears to be in the shortest function line of code.

Thank you again for any advice you could offer.
JK

4

Okay, I think I see a problem with my query: there is no single uid passing into shortest since the context is still all Resource nodes.

Seems like this is a good example of requiring foreach functionality, which to my understanding does not yet exist in DQL.

Is there any other query approach other than:

  1. Query all Resources;
  2. Outside of DQL iterate through all Resources;
  3. Iteratively Call the shortest path query for each Resource?
5

For now only Lambda is available. Not sure if we gonna implement loops(e.g. foreach), time will tell.

BTW, I’ll still check your response. I didn’t have time to focus and analyze it.

6

This block is wrong. There’s no such a syntax in DQL. You have two roots params applied. They should be two different blocks. Something like

{

  S as var(func: eq(XID, "Skill/NAICS/54"))
  T as var(func: eq(dgraph.type,"Resource"))

    

  path as shortest(from: uid(S), to: uid(T), numpaths: 1) { 
      Skill.Skills @facets(resistance)
      Skill.Resources @facets(resistance)
      Skill.Organizations @facets(resistance)
      Organization.Projects @facets(resistance)
      Project.ProjectRoles @facets(resistance)
      ProjectRole.Resource @facets(resistance)
    }
    
    path(func: uid(path)) {
     Name
     XID
    } 
  
}

But I don’t think it is possible to do a shortest path for many possible resources nodes.