ArangoDB: exists: Check whether document exists or not

‘collection.exists(object)’ method determines whether a document exists in the collection or not.

 

Signature

collection.exists(object_id)

collection.exists(object_key)

 

Let’s experiment with an example.

127.0.0.1:8529@abc_org> db.user.toArray()
[ 
  { 
    "_key" : "17089", 
    "_id" : "user/17089", 
    "_rev" : "_cRe1GKq---", 
    "id" : 1, 
    "firstName" : "Sailu", 
    "lastName" : "Ptr", 
    "age" : 32 
  }, 
  { 
    "_key" : "17091", 
    "_id" : "user/17091", 
    "_rev" : "_cRe1GKu---", 
    "id" : 2, 
    "firstName" : "Gopi", 
    "lastName" : "Battu", 
    "age" : 33 
  }, 
  { 
    "_key" : "17093", 
    "_id" : "user/17093", 
    "_rev" : "_cRe1GKy---", 
    "id" : 3, 
    "firstName" : "Krishna", 
    "lastName" : "Gurram", 
    "age" : 32 
  }, 
  { 
    "_key" : "17095", 
    "_id" : "user/17095", 
    "_rev" : "_cRe1H-6---", 
    "id" : 4, 
    "firstName" : "Venkat", 
    "lastName" : "Ptr", 
    "age" : 35 
  } 
]

 

Check for the existence by _id

127.0.0.1:8529@abc_org> db.user.exists("user/17095")
{ 
  "_id" : "user/17095", 
  "_key" : "17095", 
  "_rev" : "_cRe1H-6---" 
}

 

Check for the existence by _key

127.0.0.1:8529@abc_org> db.user.exists("17095")
{ 
  "_id" : "user/17095", 
  "_key" : "17095", 
  "_rev" : "_cRe1H-6---" 
}

You can even pass a json object as an argument to exists method.

 

db.user.exists({"_key" : "17095"})

db.user.exists({"_id" : "user/17095"})

127.0.0.1:8529@abc_org> db.user.exists({"_key" : "17095"})
{ 
  "_id" : "user/17095", 
  "_key" : "17095", 
  "_rev" : "_cRe1H-6---" 
}

127.0.0.1:8529@abc_org> db.user.exists({"_id" : "user/17095"})
{ 
  "_id" : "user/17095", 
  "_key" : "17095", 
  "_rev" : "_cRe1H-6---" 
}

This method throws a conflict when _rev is specified but the document found has a different revision already.

 

Document with correct revision

127.0.0.1:8529@abc_org> db.user.exists({"_id" : "user/17095", "_rev" : "_cRe1H-6---"})
{ 
  "_id" : "user/17095", 
  "_key" : "17095", 
  "_rev" : "_cRe1H-6---" 
}

Document with other revision

127.0.0.1:8529@abc_org> db.user.exists({"_id" : "user/17095", "_rev" : "_cRe1H-6"})
JavaScript exception in file '/usr/local/Cellar/arangodb/3.7.11_1/share/arangodb3/js/client/modules/@arangodb/arangosh.js' at 99,7: ArangoError 1200: conflict
!      throw error;
!      ^
stacktrace: ArangoError: conflict
    at Object.exports.checkRequestResult (/usr/local/Cellar/arangodb/3.7.11_1/share/arangodb3/js/client/modules/@arangodb/arangosh.js:97:21)
    at ArangoCollection.exists (/usr/local/Cellar/arangodb/3.7.11_1/share/arangodb3/js/client/modules/@arangodb/arango-collection.js:811:12)
    at <shell command>:1:9

 

 

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