Cosmos DB Connector for C#

Connect to your Azure Cosmos DB databases to read, query, create, update, and delete documents and more!

In this article you will learn how to quickly and efficiently integrate Cosmos DB data in C#. We will use high-performance Cosmos DB Connector to easily connect to Cosmos DB and then access the data inside C#.

Let's follow the steps below to see how we can accomplish that!

Download Documentation

Cosmos DB Connector for C# is based on ZappySys API Driver which is part of ODBC PowerPack. It is a collection of high-performance ODBC drivers that enable you to integrate data in SQL Server, SSIS, a programming language, or any other ODBC-compatible application. ODBC PowerPack supports various file formats, sources and destinations, including REST/SOAP API, SFTP/FTP, storage services, and plain files, to mention a few.

Create ODBC Data Source (DSN) based on ZappySys API Driver

Step-by-step instructions

To get data from Cosmos DB using C# we first need to create a DSN (Data Source) which will access data from Cosmos DB. We will later be able to read data using C#. Perform these steps:

Download and install ODBC PowerPack.
Open ODBC Data Sources (x64):
Create a User data source (User DSN) based on ZappySys API Driver:

ZappySys API Driver
- Create and use User DSN if the client application is run under a User Account. This is an ideal option in design-time, when developing a solution, e.g. in Visual Studio 2019. Use it for both type of applications - 64-bit and 32-bit.
- Create and use System DSN if the client application is launched under a System Account, e.g. as a Windows Service. Usually, this is an ideal option to use in a production environment. Use ODBC Data Source Administrator (32-bit), instead of 64-bit version, if Windows Service is a 32-bit application.
When the Configuration window appears give your data source a name if you haven't done that already, then select "Cosmos DB" from the list of Popular Connectors. If "Cosmos DB" is not present in the list, then click "Search Online" and download it. Then set the path to the location where you downloaded it. Finally, click Continue >> to proceed with configuring the DSN:

CosmosDbDSN

Cosmos DB

Now it's time to configure the Connection Manager. Select Authentication Type, e.g. Token Authentication. Then select API Base URL (in most cases, the default one is the right one). More info is available in the Authentication section.

API Key

Cosmos DB authentication

Connecting to your Azure Cosmos DB data requires you to authenticate your REST API access. Follow the instructions below:

Go to your Azure portal homepage: https://portal.azure.com/.
In the search bar at the top of the homepage, enter Azure Cosmos DB. In the dropdown that appears, select Azure Cosmos DB.
Click on the name of the database account you want to connect to (also copy and paste the name of the database account for later use).
On the next page where you can see all of the database account information, look along the left side and select Keys:
On the Keys page, you will have two tabs: Read-write Keys and Read-only Keys. If you are going to write data to your database, you need to remain on the Read-write Keys tab. If you are only going to read data from your database, you should select the Read-only Keys tab.
On the Keys page, copy the PRIMARY KEY value and paste it somewhere for later use (the SECONDARY KEY value may also be copied and used).
Now go to SSIS package or ODBC data source and use this PRIMARY KEY in API Key authentication configuration.
Enter the primary or secondary key you recorded in step 6 into the Primary or Secondary Key field.
Then enter the database account you recorded in step 3 into the Database Account field.
Next, enter or select the default database you want to connect to using the Defualt Database field.
Continue by entering or selecting the default table (i.e. container/collection) you want to connect to using the Default Table (Container/Collection) field.
Select the Test Connection button at the bottom of the window to verify proper connectivity with your Azure Devops account.
If the connection test succeeds, select OK.
Done! Now you are ready to use Asana Connector!

API Connection Manager configuration

Just perform these simple steps to finish authentication configuration:

Set Authentication Type to API Key [Http]
Optional step. Modify API Base URL if needed (in most cases default will work).
Fill in all the required parameters and set optional parameters if needed.
Finally, hit OK button:

CosmosDbDSN

Cosmos DB

API Key [Http]

https://[$Account$].documents.azure.com

Required Parameters
Primary or Secondary Key	Fill-in the parameter...
Account Name (Case-Sensitive)	Fill-in the parameter...
Database Name (keep blank to use default) Case-Sensitive	Fill-in the parameter...
API Version	Fill-in the parameter...
Optional Parameters
Default Table (needed to invoke #DirectSQL)

Once the data source connection has been configured, it's time to configure the SQL query. Select the Preview tab and then click Query Builder button to configure the SQL query:

ZappySys API Driver - Cosmos DB

Connect to your Azure Cosmos DB databases to read, query, create, update, and delete documents and more!

CosmosDbDSN
Start by selecting the Table or Endpoint you are interested in and then configure the parameters. This will generate a query that we will use in C# to retrieve data from Cosmos DB. Hit OK button to use this query in the next step.
```
#DirectSQL SELECT * FROM root where root.id !=null order by root._ts desc
```
Some parameters configured in this window will be passed to the Cosmos DB API, e.g. filtering parameters. It means that filtering will be done on the server side (instead of the client side), enabling you to get only the meaningful data much faster.
Now hit Preview Data button to preview the data using the generated SQL query. If you are satisfied with the result, use this query in C#:
ZappySys API Driver - Cosmos DB

Connect to your Azure Cosmos DB databases to read, query, create, update, and delete documents and more!

CosmosDbDSN
```
#DirectSQL SELECT * FROM root where root.id !=null order by root._ts desc
```
You can also access data quickly from the tables dropdown by selecting <Select table>.

A WHERE clause, LIMIT keyword will be performed on the client side, meaning that the whole result set will be retrieved from the Cosmos DB API first, and only then the filtering will be applied to the data. If possible, it is recommended to use parameters in Query Builder to filter the data on the server side (in Cosmos DB servers).
Click OK to finish creating the data source.

Video Tutorial

Read data in C#

Using ODBC DSN

Use this code snippet to read the data using CosmosDbDSN data source:

"CosmosDbDSN" ;
Press F5 to run the code and read the data:

Here is the code in text format:

using System;
using System.Data.Odbc;

namespace ConsoleApp {
    class Program {
        static void Main() {
            var dsn = "CosmosDbDSN";
            using (var conn = new OdbcConnection(String.Format("DSN={0}", dsn)))
            {
                conn.Open();
                var cmd = new OdbcCommand("SELECT * FROM Products", conn);
                
                //Increase the timeout duration from the default 30 seconds, which may be insufficient in certain scenarios
                cmd.CommandTimeout=600; // 600-Seconds
                
                var rdr = cmd.ExecuteReader();
                while (rdr.Read())
                {
                    for (int i = 0; i < rdr.FieldCount; i++)
                    {
                            Console.Write("{0}\t", rdr[i]);
                    }
                    Console.WriteLine();
                }
            }
            Console.ReadKey();
        }
    }
}

Using a full ODBC connection string

If you want to avoid being dependent on a DSN and creating multiple DSNs for each platform (x86, x64), then you can use a fully qualified connection string. Simply go to your DSN and copy the Connection String:

Open ODBC data source configuration and click Copy settings:

ZappySys API Driver - Configuration [Version: 2.0.1.10418]

ZappySys API Driver - Cosmos DB

Connect to your Azure Cosmos DB databases to read, query, create, update, and delete documents and more!

CosmosDbDSN
The window opens, telling us the connection string was successfully copied to the clipboard:

Then in your C# code, pass the connection string as an argument when calling the OdbcConnection object's constructor, for example:

var connectionString = @"DRIVER={ZappySys API Driver};ServiceUrl=https://[$Account$].documents.azure.com;CredentialType=HashSignature;HashSignatureFormat=[$http-method$]-lc[$lf$][$url-part-regex-(/(?<resourcetype>dbs|colls|docs|users|permissions|sprocs|attachments|pkranges)(/([\w\d-\$\.=])+)?$){{0,resourcetype}}$]-lc[$lf$][$url-part-regex-(?<id>dbs/([\w \d-+=.]+)$)|((?<id>dbs/(.*?))/(colls|docs|users|attachments|permissions||pkranges)$)|(?<id>dbs/(.*)/(colls|docs|users|attachments|permissions)/[\w \d-+.=]+$){{0,id}}$][$lf$][$timestamp$]-lc[$lf$][$lf$];ExtraHeaders=x-ms-date: [$timestamp$]||x-ms-version: [$ApiVersion$]||Authorization:type%3dmaster%26ver%3d1.0%26sig%3d[$signature$]-enc;HashTimestampFormat=r;";

using (var conn = new OdbcConnection(connectionString))
{
    // your code goes here
}

Limitations of using a full connection string

Despite using a full ODBC connection string may be very convenient it comes with a limitation: it's length is limited to 1024 symbols (or sometimes more). It usually happens when API provider generates a very long Refresh Token when OAuth is at play. If you are using such a long ODBC connection string, you may get this error:

"Connection string exceeds maximum allowed length of 1024"

But there is a solution to this by storing the full connection string in a file. Follow the steps below to achieve this:

Open your ODBC data source.
Click Copy settings button to copy a full connection string (see the previous section on how to accomplish that).
Then create a new file, let's say, in C:\temp\odbc-connection-string.txt.
Continue by pasting the copied connection string into a newly created file and save it.
Finally, the last step! Just construct a shorter ODBC connection string using this format:
```
DRIVER={ZappySys API Driver};SettingsFile=C:\temp\odbc-connection-string.txt
```
Our troubles are over! Now you should be able to use this connection string in C# with no problems.

This feature requires ODBC PowerPack v1.9.0 or later.

Centralized data access via Data Gateway

In some situations, you may need to provide Cosmos DB data access to multiple users or services. Configuring the data source on a Data Gateway creates a single, centralized connection point for this purpose.

This configuration provides two primary advantages:

Centralized data access
The data source is configured once on the gateway, eliminating the need to set it up individually on each user's machine or application. This significantly simplifies the management process.
Centralized access control
Since all connections route through the gateway, access can be governed or revoked from a single location for all users.

	Data Gateway	Local ODBC data source
Simple configuration
Installation	Single machine	Per machine
Connectivity	Local and remote	Local only
Connections limit	Limited by License	Unlimited
Central data access
Central access control
More flexible cost

If you need any of these requirements, you will have to create a data source in Data Gateway to connect to Cosmos DB, and to create an ODBC data source to connect to Data Gateway in C#.

Let's not wait and get going!

Creating Cosmos DB data source in Gateway

In this section we will create a data source for Cosmos DB in Data Gateway. Let's follow these steps to accomplish that:

Search for gateway in Windows Start Menu and open ZappySys Data Gateway Configuration:
Go to Users tab and follow these steps to add a Data Gateway user:
- Click Add button
- In Login field enter username, e.g., john
- Then enter a Password
- Check Is Administrator checkbox
- Click OK to save
Now we are ready to add a data source:
- Click Add button
- Give Datasource a name (have it handy for later)
- Then select Native - ZappySys API Driver
- Finally, click OK
CosmosDbDSN

ZappySys API Driver
When the ZappySys API Driver configuration window opens, configure the Data Source the same way you configured it in ODBC Data Sources (64-bit), in the beginning of this article.
Very important step. Now, after creating or modifying the data source make sure you:
- Click the Save button to persist your changes.
- Hit Yes, once asked if you want to restart the Data Gateway service.
This will ensure all changes are properly applied:

Skipping this step may result in the new settings not taking effect and, therefore you will not be able to connect to the data source.

Creating ODBC data source for Data Gateway

In this part we will create ODBC data source to connect to Data Gateway from C#. To achieve that, let's perform these steps:

Open ODBC Data Sources (x64):
Create a User data source (User DSN) based on ODBC Driver 17 for SQL Server:

ODBC Driver 17 for SQL Server

If you don't see ODBC Driver 17 for SQL Server driver in the list, choose a similar version driver.
Then set a Name of the data source (e.g. Gateway) and the address of the Data Gateway:

GatewayDSN

localhost,5000

Make sure you separate the hostname and port with a comma, e.g. localhost,5000.
Proceed with authentication part:
- Select SQL Server authentication
- In Login ID field enter the user name you used in Data Gateway, e.g., john
- Set Password to the one you configured in Data Gateway
Then set the default database property to CosmosDbDSN (the one we used in Data Gateway):

CosmosDbDSN
Continue by checking Trust server certificate option:
Once you do that, test the connection:
If connection is successful, everything is good:
Done!

We are ready to move to the final step. Let's do it!

Accessing data in C# via Data Gateway

Finally, we are ready to read data from Cosmos DB in C# via Data Gateway. Follow these final steps:

Go back to C#.
Use this code snippet to read the data using GatewayDSN data source:

"GatewayDSN" ;
Read the data the same way we discussed at the beginning of this article.
That's it!

Now you can connect to Cosmos DB data in C# via the Data Gateway.

If you are asked for authentication details, use Database authentication or SQL Authentication option and enter credentials you used when configuring Data Gateway, e.g. john and your password.