In RethinkDB, what is the easiest way to check if a database or a table exists?

Question

One way I know I can do it is by listing throughdbList() and tableList() and then looking for what I want in the results.

Is there an easier way?

EDIT

My goal is to create a table in case it doesn't exist.

for example you can try to create table, if it's already exists, you will see error: RqlRuntimeError: Table already exists — Suvitruf - Andrei Apanasik, Jul 25 '15 at 11:43
What are you trying to achieve? Do you want to create a database if it doesn't exist, or simply check if it exists? — Tholle, Jul 25 '15 at 18:31
@Suvitruf, thanks for the reply. I wasn't really interested in throwing an error.. I just wanted to check whether it existed. — André Pena, Jul 26 '15 at 02:57
@Tholle, yes. I want to create a table in case it doesn't exist. — André Pena, Jul 26 '15 at 02:57

Tholle · Accepted Answer · 2016-04-24T08:39:53.677

If you want to create a database if it does not exists, or get a value like "database already exists" if it does exist, you could do something like the following:

r.dbList().contains('example_database')
  .do(function(databaseExists) {
    return r.branch(
      databaseExists,
      { dbs_created: 0 },
      r.dbCreate('example_database')
    );
  }).run();

It will return the following if it is created:

{
  "config_changes": [
    {
      "new_val": {
        "id": "1ee7ddb4-6e2c-43bb-a0f5-64ef6a6211a8",
        "name": "example_database"
      },
      "old_val": null
    }
  ],
  "dbs_created": 1
}

And this if it already exists:

{
  "dbs_created": 0
}

@Tholle why so complicated? my version with python: `for table in self.tables: if not rdb.db(self.db).table_list().contains(table).run(): rdb.db(self.db).table_create(table).run()` — holms, Jun 11 '16 at 23:51

xyztdanid4 · Answer 2 · 2016-10-02T13:07:02.850

For the table existing checking I have found the following solution:

r.tableList().run(connection); //['people']

this will give you back an array of the tables which are defined on the default DB for example: ['people']. (if you want to set it do this: connection.use('test');)

then we can check if the array is containing our table name to create.

_.some(tableNames, tableName)

put it all together:

  if (!_.isNil(tableName) && _.isString(tableName) && !_.isNil(connection)) {
    r.tableList().run(connection).then(function(tableNames) {
      if (_.includes(tableNames, tableName)) {
        return r.tableCreate(tableName).run(connection);
      } else {
        return;
        }
    });
  }

score 2 · Answer 3 · answered Nov 29 '17 at 18:20

2

In JavaScript, given an array of table names, the shortest way is

const tables = ['table1Name', 'table2Name', ...]
const db = 'myDb'

r(tables)
    .difference(r.db(db).tableList())
    .forEach(table => r.db(db).tableCreate(table))
    .run(connection)

answered Nov 29 '17 at 18:20

vbranden

4,758
1
18
12

Don't you need a `run()` after `r.db(db).tableList()` ? – Théo Champion Sep 21 '18 at 08:36
No you only need to call run at the end of your entire query – vbranden Sep 21 '18 at 18:28

score 0 · Answer 4 · answered May 17 '21 at 15:41

For anyone coming from VB.net then solution would be like this.. one liner

Dim RDBDatabase as String = "dbName" 
Dim RDBTable as String = "tableName"  
   
Dim CheckDB = R.DbList().Contains(RDBDatabase).Do_(Function(databaseExists) R.Branch(databaseExists, "db done", R.DbCreate(RDBDatabase))).And(R.Db(RDBDatabase).TableList().Contains(RDBTable).Do_(Function(tableExists) R.Branch(tableExists, "tb done", R.Db(RDBDatabase).TableCreate(RDBTable)))).Run(conn)

This will create DB if it doesn't exists and will create the table if it doesn't exist

If neither exists then it will return values from the last created which is the table

{{
  "config_changes": [
    {
      "new_val": {
        "db": "dbName",
        "durability": "hard",
        "id": "0f72a570-7998-49f7-affc-96cbdd1ea086",
        "indexes": [],
        "name": "tableName",
        "primary_key": "id",
        "shards": [
          {
            "nonvoting_replicas": [],
            "primary_replica": "replicasssss_iu1",
            "replicas": [
              "replicasssss_iu1"
            ]
          }
        ],
        "write_acks": "majority"
      },
      "old_val": null
    }
  ],
  "tables_created": 1
}}

In RethinkDB, what is the easiest way to check if a database or a table exists?

4 Answers4

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