在 Robo3T 中，如何添加自定义功能

Question

I just installed Robo3T( previously named robomongo), which has a GUI for mongo db. I want to add a custom function to help me get the last N documents in normal order, the query statement is like this:

db.getCollection('i1801').find().skip(db.getCollection('i1801').count() - 1200)

And I found from stackoverflow( mongodb: how to get the last N records? ), this can be written as a function like this:

function last(N) {
    return db.collection.find().skip(db.collection.count() - N);
}

And I go back to my Robo3T, trying to add a custom function last() , but didn't work, nothing showed up under function tab.

I have attached some screen captures illustrating this issue:

After I clicked save button, nothing happened, still no functions under function tab. And the log shows function last created, and function tab being refreshed.

So, how can I add a last function here?

Answer 1

Tried the steps you listed, it worked for simple find statements. When I added the 'skip', the save failed. Even updating an existing function didn't work. Maybe an issue with Robo? I dont know.

Anyway, to add the function in Robo3t

1. Right click collection
2. Select Open Shell
3. On the shell type the following

 db.system.js.save( { _id: "last", value : function last(x) { return db.test.find().skip(db.test.count() - x); } } )

Lastly, Run the script and refresh Function folder.

Answer 2

For calling function:

db.loadServerScripts();
callyourfunction();

1. Right click on collection
   
2. Click on open shell
   https://i.stack.imgur.com/YTiGc.jpg
   
3. In shell run db.loadServerScripts();
   https://i.stack.imgur.com/BDTBT.jpg
   
4. call user function like: addTwo(2,5);
   https://i.stack.imgur.com/EujGo.jpg

NOTE :: For seen output, Make sure your function should be a return value