Building a Custom API Connector for C#

Read / write Custom API data in C# without coding.

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

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

Download Documentation

Building a Custom API 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 Custom API Connector

First of all, you will have to create your own API connector. For demonstration purposes, in this section we will create a simple Hello-World API connector that calls ZappySys Sandbox World API endpoint https://sandbox.zappysys.com/api/world/hello. When developing your Custom API Connector, just replace it with your real API method/endpoint. Let's dive in and follow these steps:

Open ODBC Data Sources (x64):
Create a User data source (User DSN) based on ZappySys JSON Driver:

ZappySys JSON Driver
Once the data source configuration window opens, enter this URL into the text box:

https://sandbox.zappysys.com/api/world/hello
Then go to the Preview tab and try to say "Hello!" to the World!
Since the test is successful, you are ready to create the Hello-World Connector:
The API Connector File Wizard opens, click Next:
Leave the default option, and click Next again:
Just click Next in the next window:
Let's give our new custom connector a name it deserves:
Then just click Next in the Connection Types window:
Let's name the hello endpoint (it deserves a name too!):
When the next window opens, delete the default table (we won't need it for now):
Finally, specify a path, where you want to save the newly created API Connector:

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

Step-by-step instructions

To get data from Custom API using C# we first need to create a DSN (Data Source) which will access data from Custom API. 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
When the Configuration window appears give your data source a name if you haven't done that already. Then set the path to your created Custom API Connector (in the example below, we use Hello-World Connector). Finally, click Continue >> to proceed:
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). Check your Custom API reference for more information on how to authenticate.
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 - Custom API

Read / write Custom API data in C# without coding.

CustomApiDSN
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 Custom API. Hit OK button to use this query in the next step.
```
SELECT * FROM Orders
```
Some parameters configured in this window will be passed to the Custom 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 - Custom API

Read / write Custom API data in C# without coding.

CustomApiDSN
```
SELECT * FROM Orders
```
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 Custom 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 Custom API 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 CustomApiDSN data source:

"CustomApiDSN" ;
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 = "CustomApiDSN";
            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 - Custom API

Read / write Custom API data in C# without coding.

CustomApiDSN
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://sandbox.zappysys.com/api/world;CredentialType=Basic;";

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 Custom API 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 Custom API, and to create an ODBC data source to connect to Data Gateway in C#.

Let's not wait and get going!

Creating Custom API data source in Gateway

In this section we will create a data source for Custom API 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
CustomApiDSN

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 CustomApiDSN (the one we used in Data Gateway):

CustomApiDSN
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 Custom API 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 Custom API 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.