Arangosh Details

Interaction

You can paste multiple lines into Arangosh, given the first line ends with anopening brace:

arangosh> for (var i = 0; i < 10; i ++) {
........>         require("@arangodb").print("Hello world " + i + "!\n");
........> }

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Hello world 0!
 
Hello world 1!
 
Hello world 2!
 
Hello world 3!
 
Hello world 4!
 
Hello world 5!
 
Hello world 6!
 
Hello world 7!
 
Hello world 8!
 
Hello world 9!

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To load your own JavaScript code into the current JavaScript interpreter context,use the load command:

require("internal").load("/tmp/test.js")     // <- Linux / macOS
require("internal").load("c:\\tmp\\test.js") // <- Windows

Exiting arangosh can be done using the key combination <CTRL> + D or bytyping quit<CR>

Shell Output

The ArangoDB shell will print the output of the last evaluated expressionby default:

arangosh> 42 * 23

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966

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In order to prevent printing the result of the last evaluated expression,the expression result can be captured in a variable, e.g.

arangosh> var calculationResult = 42 * 23

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There is also the print function to explicitly print out values in theArangoDB shell:

arangosh> print({ a: "123", b: [1,2,3], c: "test" });

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{ 
  "a" : "123", 
  "b" : [ 
    1, 
    2, 
    3 
  ], 
  "c" : "test" 
}

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By default, the ArangoDB shell uses a pretty printer when JSON documents areprinted. This ensures documents are printed in a human-readable way:

arangosh> db._create("five")
arangosh> for (i = 0; i < 5; i++) db.five.save({value:i})
arangosh> db.five.toArray()

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[ArangoCollection 87549, "five" (type document, status loaded)]
[ 
  { 
    "_key" : "87554", 
    "_id" : "five/87554", 
    "_rev" : "_ZP4PZl6---", 
    "value" : 0 
  }, 
  { 
    "_key" : "87556", 
    "_id" : "five/87556", 
    "_rev" : "_ZP4PZm----", 
    "value" : 1 
  }, 
  { 
    "_key" : "87558", 
    "_id" : "five/87558", 
    "_rev" : "_ZP4PZm---A", 
    "value" : 2 
  }, 
  { 
    "_key" : "87560", 
    "_id" : "five/87560", 
    "_rev" : "_ZP4PZmC---", 
    "value" : 3 
  }, 
  { 
    "_key" : "87562", 
    "_id" : "five/87562", 
    "_rev" : "_ZP4PZmC--A", 
    "value" : 4 
  } 
]

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While the pretty-printer produces nice looking results, it will need a lot ofscreen space for each document. Sometimes a more dense output might be better.In this case, the pretty printer can be turned off using the commandstop_pretty_print().

To turn on pretty printing again, use the start_pretty_print() command.

Escaping

In AQL, escaping is done traditionally with the backslash character: \.As seen above, this leads to double backslashes when specifying Windows paths.Arangosh requires another level of escaping, also with the backslash character.It adds up to four backslashes that need to be written in Arangosh for a singleliteral backslash (c:\tmp\test.js):

db._query('RETURN "c:\\\\tmp\\\\test.js"')

You can use bind variables tomitigate this:

var somepath = "c:\\tmp\\test.js"
db._query(aql`RETURN ${somepath}`)

Database Wrappers

Arangosh provides the db object by default, and this object canbe used for switching to a different database and managing collections inside thecurrent database.

For a list of available methods for the db object, type

arangosh> db._help(); 

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--------------------------- ArangoDatabase (db) help ---------------------------
Administration Functions:                                                 
  _help()                               this help                         
  _flushCache()                         flush and refill collection cache 
 
Collection Functions:                                                     
  _collections()                        list all collections              
  _collection(<name>)                   get collection by identifier/name 
  _create(<name>, <properties>)         creates a new collection          
  _createEdgeCollection(<name>)         creates a new edge collection     
  _drop(<name>)                         delete a collection               
 
Document Functions:                                                       
  _document(<id>)                       get document by handle (_id)      
  _replace(<id>, <data>, <overwrite>)   overwrite document                
  _update(<id>, <data>, <overwrite>,    partially update document         
          <keepNull>)                                                     
  _remove(<id>)                         delete document                   
  _exists(<id>)                         checks whether a document exists  
  _truncate()                           delete all documents              
 
Database Management Functions:                                            
  _createDatabase(<name>)               creates a new database            
  _dropDatabase(<name>)                 drops an existing database        
  _useDatabase(<name>)                  switches into an existing database
  _drop(<name>)                         delete a collection               
  _name()                               name of the current database      
 
Query / Transaction Functions:                                            
  _executeTransaction(<transaction>)    execute transaction               
  _query(<query>)                       execute AQL query                 
  _createStatement(<data>)              create and return AQL query       
 
View Functions:                                                           
  _views()                              list all views                    
  _view(<name>)                         get view by name                  
  _createView(<name>, <type>,           creates a new view                
              <properties>)                                               
  _dropView(<name>)                     delete a view

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The db object is available in arangosh_as well as on _arangod i.e. if you’re using Foxx. While itsinterface is persistent between the arangosh and the arangod implementations,its underpinning is not. The arangod implementation are JavaScript wrappersaround ArangoDB’s native C++ implementation, whereas the arangosh implementationwraps HTTP accesses to ArangoDB’s RESTfull API.

So while this code may produce similar results when executed in arangosh andarangod, the CPU usage and time required will be really different since thearangosh version will be doing around 100k HTTP requests, and thearangod version will directly write to the database:

for (i = 0; i < 100000; i++) {
    db.test.save({ name: { first: "Jan" }, count: i});
}

Using arangosh via unix shebang mechanisms

In unix operating systems you can start scripts by specifying the interpreter in the first line of the script.This is commonly called shebang or hash bang. You can also do that with arangosh, i.e. create ~/test.js:

#!/usr/bin/arangosh --javascript.execute 
require("internal").print("hello world")
db._query("FOR x IN test RETURN x").toArray()

Note that the first line has to end with a blank in order to make it work.Mark it executable to the OS:

#> chmod a+x ~/test.js

and finaly try it out:

#> ~/test.js

Shell Configuration

arangosh will look for a user-defined startup script named .arangosh.rc in theuser’s home directory on startup. The home directory will likely be /home/<username>/on Unix/Linux, and is determined on Windows by peeking into the environment variables%HOMEDRIVE% and %HOMEPATH%.

If the file .arangosh.rc is present in the home directory, arangosh will executethe contents of this file inside the global scope.

You can use this to define your own extra variables and functions that you need often.For example, you could put the following into the .arangosh.rc file in your homedirectory:

// "var" keyword avoided intentionally...
// otherwise "timed" would not survive the scope of this script
global.timed = function (cb) {
  console.time("callback");
  cb();
  console.timeEnd("callback");
};

This will make a function named timed available in arangosh in the global scope.

You can now start arangosh and invoke the function like this:

timed(function () { 
  for (var i = 0; i < 1000; ++i) {
    db.test.save({ value: i }); 
  }
});

Please keep in mind that, if present, the .arangosh.rc file needs to contain validJavaScript code. If you want any variables in the global scope to survive you need toomit the var keyword for them. Otherwise the variables will only be visible insidethe script itself, but not outside.