How to add, edit, check existence of LINK in LINKSET ?

[Gaurav Dhiman]

How to add, edit and check an existence of LINK in LINKSET ?

Considering below case for document based database, can some on give me code example for add, edit and check existence cases.

Lets say

company.employees is LINKSET (array of links to employee objects)

employee.company is LINK (reverse link to company object)

While adding employee, I need to do two way linking (company to employee and employee to company), how to do it ?

var emp = db.getInstance("employee");

emp.field("name", "John");

emp.field("age", "35");

emp.filed("company", "#2:4");     // Linked from employee to company

company.field("employees", ?????);   // How to create link from company to employee ?

Regards,

Gaurav

[Gaurav Dhiman]

I mean add, delete (not edit) and check existence.

Best Regards,

Gaurav

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[Arve Knudsen]

Gaurav, regarding adding to a linkset, you may remember my question on StackOverflow about saving document links with a document. My answer to that question shows how to do this, and it looks like it would solve your example.

Hope this helps,

Arve

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[Gaurav Dhiman]

Thanks Arve for response, but I am still not clear.

My queries are simple. I am using OrientDB Javascript functions:

Just for example, if my company.employees = [#4:1, #4:5, #4:3]

1. How can I add #4:6 to linkset ? After addition it should be [#4:1, #4:5, #4:3, #4:6]

2. How can I delete #4:5 from linkset ? After deletion it should be [#4:1, #4:3, #4:6]

3. If I add #4:1 again to linkset, will it check for duplicate and return error or do I need to check problematically before adding to linset ? If I need to do it, how to do it ?

I am sure there must be some methods to add, delete and check existence on linkset & linkmap, I am not just aware of those.

Any pointers will be helpful.

Thanks once again !

Regards,

Gaurav

[Gaurav Dhiman]

Can anyone share code example (JavaScript) to do this ?

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[Luca Garulli]

Look at the answer to your question on StackOverflow: http://stackoverflow.com/questions/22715353/how-to-add-delete-and-check-existence-with-linkset-in-orientdb/22734521#22734521

Lvc@

[Gaurav Dhiman]

Thanks Luca, it helped me.

Are there some methods of ODocument object also that can be used to add, delete objects from collections (LINKSET / LINKMAP). Something like below:

comp = db.query("select from company #9:0");

comp = comp[0];

comp.add("employees", #10:4); OR comp.add("employees", emp);  // emp being object / record not @rid

comp.remove("employees", #10:2); OR comp.remove("employees", emp);   // emp being object / record not @rid

comp.save();

db.commit();

Regards,

Gaurav

[Nhat Nguyen]

Is there a java example to crud link/linkset/linklist/linkmap into a record<ODocument>?

Regards,

Nhat

[Arve Knudsen]

Nhat, my answer on StackOverflow shows how to create an ODocument with a linkset, in Scala. Scala is so close to Java, that you should be able to figure it out. My advice apart from this is to declare in the database schema that your properties are link/linkset etc., so that you'll get an error if you supply the wrong type from Java.

Hth,

Arve

[Gaurav Dhiman]

As suggested by Arve, its advisable to define the property as LINK or LINKSET or LINKMAP (whatever). If you do so, simple assignment of one ODocument to property will LINK it, as internally OrientDB seems to understand that its linking in embedding.

Example:

comp = db.getInstance("Company");

comp.field("name","Company name");

comp.save();

db.commit();

for (i= 0; i<5; i++) {

   emp = db.getInstance("Employee");

   emp.field("name", "Employee name");

   emp.field("company", comp);      // saving LINK

   emp.save();

   emps[i] = emp;

}

db.commit();

comp.field("employees", emps);      // saving LINKSET / LINKMAP

comp.save();

db.commit();

Hope it helps.

Best Regards,

Gaurav

http://www.linkedin.com/in/gauravdhiman

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[Nhat Nguyen]

Hey,

great thanks. I am a bit curious couldn´t you have just done one "db.commit()" at the end? 

Maybe i missed something.

[Kevin Daly]

Is there a way of doing this efficiently with the Document Java API?

I am looking at a possibility to have 180,000,000 links stored in a linkset so not sure if using .field would work.