Querying with Select

The following example shows how to retrieve the _id and address.zipCode fields from all documents in a store using an OJAI query.

/*
 * Copyright (c) 2018 MapR, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

const { ConnectionManager } = require('node-maprdb');

const connectionString = 'localhost:5678?' +
  'auth=basic;' +
  'user=mapr;' +
  'password=mapr;' +
  'ssl=true;' +
  'sslCA=/opt/mapr/conf/ssl_truststore.pem;' +
  'sslTargetNameOverride=node1.mapr.com';

let connection;

// Create a connection to data access server
ConnectionManager.getConnection(connectionString)
  .then((conn) => {
    connection = conn;
    // Get a store
    return connection.getStore('/demo_table');
  })
  .then((store) => {
    // Create an OJAI query
    const query = {"$select": ["_id", "address.zipCode"]};
    // fetch OJAI Documents by query
    return store.find(query);
  })
  .then((queryResult) => {
    queryResult.on('data', (document) => {
      // Print OJAI Documents from document stream
      console.log(document);
    });
    queryResult.on('end', () => {
      // close the OJAI connection
      connection.close();
    });
  });

The following example shows how to retrieve the _id and address.zipCode fields from all documents in a store using an OJAI query.

from mapr.ojai.storage.ConnectionFactory import ConnectionFactory

# Create a connection to data access server
connection_str = "localhost:5678?auth=basic;user=mapr;password=mapr;" \
          "ssl=true;" \
          "sslCA=/opt/mapr/conf/ssl_truststore.pem;" \
          "sslTargetNameOverride=node1.mapr.com"
connection = ConnectionFactory.get_connection(connection_str=connection_str)

# Get a store and assign it as a DocumentStore object
store = connection.get_store('/demo_table')

# Create an OJAI query
query = {"$select": ["_id", "address.zipCode"]}

# options for find request
options = {
    'ojai.mapr.query.result-as-document': True
    }

# fetch OJAI Documents by query
query_result = store.find(query, options=options)

# Print OJAI Documents from document stream
for doc in query_result:
    print(doc.as_dictionary())

# close the OJAI connection
connection.close()

The following two dbshell commands are equivalent to the code examples. See dbshell find or findbyid for more details about the syntax dbshell provides.

# mapr dbshell
maprdb root:> find /demo_table --query {"$select":["_id","address.zipcode"]}

maprdb root:> find /demo_table --fields _id,address.zipcode 

The following example shows how to retrieve the _id and address.zipCode fields from all documents in a store using an OJAI query.

using System;
using MapRDB.Driver;
using MapRDB.Driver.Ojai;

public class FindQueryWithSelect
{
	public async void FindQueryWithSelect()
	{
        // Create a connection to data access server
        var connectionStr = $"localhost:5678?auth=basic;" +
            $"user=mapr;" +
            $"password=mapr;" +
            $"ssl=true;" +
            $"sslCA=/opt/mapr/conf/ssl_truststore.pem;" +
            $"sslTargetNameOverride=node1.mapr.com";
        var connection = ConnectionFactory.CreateConnection(connectionStr);

        // Get a store and assign it as a DocumentStore object
        var store = connection.GetStore("/demo_table");

        //Create an OJAI query
        var query = connection.NewQuery().Select("_id", "address.zipCode").Build();

        // Options for find request
        var options = new QueryOptions(1000, true);

        // Fetch OJAI Documents by query
        var queryResult = store.Find(query, options);

        var documentStream = await queryResult.GetDocumentAsyncStream().GetAllDocuments();
        // Print OJAI Documents from document stream
        foreach (var document in documentStream)
        {
            Console.WriteLine(document.ToDictionary());
        }

        // Close the OJAI connection
        connection.Close();
    }
}

The following example shows how to retrieve the _id and address.zipCode fields from all documents in a store using an OJAI query.

package main

import (
	"fmt"
	client "github.com/mapr/private-maprdb-go-client"
)

func main() {
	// Create connection string
	connectionString := "192.168.33.11:5678?" +
		"auth=basic;" +
		"user=mapr;" +
		"password=mapr;" +
		"ssl=true;" +
		"sslCA=/opt/mapr/conf/ssl_truststore.pem;" +
		"sslTargetNameOverride=node1.cluster.com"

	storeName := "/demo_table"

	// Create a connection to DAG
	connection, err := client.MakeConnection(connectionString)
	if err != nil {
		panic(err)
	}

	// Get a store and assign it as a DocumentStore struct
	store, err := connection.GetStore(storeName)
	if err != nil {
		panic(err)
	}

	// Options for find request
	options := &client.FindOptions{ResultAsDocument: true}

	// Create an OJAI query
	query := map[string]interface{}{"$select": []interface{}{"_id", "address.zipCode"}}

	// Fetch all OJAI Documents from table
	findResult, err := store.FindQueryMap(query, options)

	// Print OJAI Documents from document stream
	for _, doc := range findResult.DocumentList() {
		fmt.Println(doc)
	}

	// Close connection
	connection.Close()
}