Building a Custom API Connector for C# In this article you will learn how to integrate Custom API data in C# (live / bi-directional connection to Custom API). Read / write Custom API data in C# without coding.. Using Custom API Connector you will be able to connect, read, and write data from within C#. Follow the steps below to see how we would accomplish that. Download Documentation The driver mentioned above is part of ODBC PowerPack which is a collection of high-performance Drivers for various API data source (i.e. REST API, JSON, XML, CSV, Amazon S3 and many more). Using familiar SQL query language you can make live connections and read/write data from API sources or JSON / XML / CSV Files inside SQL Server (T-SQL) or your favorite Reporting (i.e. Power BI, Tableau, Qlik, SSRS, MicroStrategy, Excel, MS Access), ETL Tools (i.e. Informatica, Talend, Pentaho, SSIS). You can also call our drivers from programming languages such as JAVA, C#, Python, PowerShell etc. If you are new to ODBC and ZappySys ODBC PowerPack then check the following links to get started. ODBC PowerPack - System Requirements and Installation Getting Started - Using ODBC PowerPack ODBC API Driver Help File

Connect to Custom API Connector in other apps Custom API Connector for SSIS Custom API Connector for SQL Server Custom API Connector for Power BI Custom API Connector for SSRS Custom API Connector for Informatica Custom API Connector for MS Access Custom API Connector for MS Excel Custom API Connector for SSAS Custom API Connector for Python Custom API Connector for JAVA Custom API Connector for Tableau Custom API Connector for SAP Crystal Reports Custom API Connector for Azure Data Factory (Pipeline) Custom API Connector for Azure Data Factory (SSIS) Custom API Connector for Talend Studio Custom API Connector for UiPath Custom API Connector for PowerShell Custom API Connector for ODBC

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:

1. Install ZappySys ODBC PowerPack.

2. Open ODBC Data Sources (x64):
   

3. Create a User Data Source (User DSN) based on ZappySys JSON Driver

   ZappySys JSON Driver

   

4. 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:

   

5. 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.

6. Once the data source has been configured, you can preview data. Select the Preview tab and use settings similar to the following to preview data:
   

7. Click OK to finish creating the data source.

Video instructions

Read data in C#

Using ODBC DSN

1. Create a new Console project and use this code to read the data:
   

   "CustomApiConnectorDSN";

   

2. Press F5 to run the code and read the data:
   

3. Here is the code in text format:

   using System;
   using System.Data.Odbc;
   
   namespace ConsoleApp {
       class Program {
           static void Main() {
               var dsn = "CustomApiConnectorDSN";
               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:

1. Open ODBC data source configuration and click Copy settings:
   

   ZappySys JSON Driver - Custom API Connector

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

   CustomApiConnectorDSN

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

3. 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 JSON Driver};SomeProperty=12345;AnotherProperty=some_value;";
   
   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. It usually happens when API provider generates a very long Refresh Token when OAuth is at play. If it happens you use such API, you may get this error:

"Connection string exceeds maximum allowed length of 1024"

But there is a solution to this by storing the Refresh Token in a file instead of directly in ODBC connection string. Follow the steps below to achieve this.

1. Open your ODBC data source
2. Hit Advanced tab and enter a file path:
   

   ZappySys JSON Driver - Custom API Connector

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

   CustomApiConnectorDSN

   
   If you cannot find the Advanced tab, try looking for Click to Configure link in Properties tab, under URL text box. Click it, and then configure the file path in OAuth Grant Options tab.
3. Then click Copy settings button to copy a full connection string and paste it into your script.
4. Proceed by pasting the connection string into your C# code as an argument when calling the OdbcConnection object's constructor.
5. Remove long AccessToken and RefreshToken properties from the connection string, and leave RefreshTokenFile property intact together with all the other properties:

   var connectionString = "Driver={ZappySys JSON Driver};RefreshTokenFile=C:\Users\john\Documents\tokens.txt;SomeProperty=12345;AnotherProperty=some_value;[AllOtherProperties=...]";
       using (var conn = new OdbcConnection(connectionString))
       {
           // your code goes here
       }

   AccessToken and RefreshToken will be stored in C:\Users\john\Documents\tokens.txt, specified by RefreshTokenFile property.
6. Our troubles are over, now you should be able to execute the script with no problems.

Advanced topics

Create Custom Stored Procedure in ZappySys Driver

You can create procedures to encapsulate custom logic and then only pass handful parameters rather than long SQL to execute your API call.

Steps to create Custom Stored Procedure in ZappySys Driver. You can insert Placeholders anywhere inside Procedure Body. Read more about placeholders here

1. Go to Custom Objects Tab and Click on Add button and Select Add Procedure:
   

2. Enter the desired Procedure name and click on OK:
   

3. Select the created Stored Procedure and write the your desired stored procedure and Save it and it will create the custom stored procedure in the ZappySys Driver:
   Here is an example stored procedure for ZappySys Driver. You can insert Placeholders anywhere inside Procedure Body. Read more about placeholders here
   

   CREATE PROCEDURE [usp_get_orders]
       @fromdate = '<<yyyy-MM-dd,FUN_TODAY>>'
    AS
       SELECT * FROM Orders where OrderDate >= '<@fromdate>';
   

   
   

4. That's it now go to Preview Tab and Execute your Stored Procedure using Exec Command. In this example it will extract the orders from the date 1996-01-01:
   

   Exec usp_get_orders '1996-01-01';

   
   

5. Let's generate the SQL Server Query Code to make the API call using stored procedure. Go to Code Generator Tab, select language as SQL Server and click on Generate button the generate the code.
   As we already created the linked server for this Data Source, in that you just need to copy the Select Query and need to use the linked server name which we have apply on the place of [MY_API_SERVICE] placeholder.
   

   SELECT * FROM OPENQUERY([MY_API_SERVICE], 'EXEC usp_get_orders @fromdate=''1996-07-30''')

   
   

6. Now go to SQL served and execute that query and it will make the API call using stored procedure and provide you the response.
   

Create Custom Virtual Table in ZappySys Driver

ZappySys API Drivers support flexible Query language so you can override Default Properties you configured on Data Source such as URL, Body. This way you don't have to create multiple Data Sources if you like to read data from multiple EndPoints. However not every application support supplying custom SQL to driver so you can only select Table from list returned from driver.

If you're dealing with Microsoft Access and need to import data from an SQL query, it's important to note that Access doesn't allow direct import of SQL queries. Instead, you can create custom objects (Virtual Tables) to handle the import process.

Many applications like MS Access, Informatica Designer wont give you option to specify custom SQL when you import Objects. In such case Virtual Table is very useful. You can create many Virtual Tables on the same Data Source (e.g. If you have 50 URLs with slight variations you can create virtual tables with just URL as Parameter setting.

1. Go to Custom Objects Tab and Click on Add button and Select Add Table:
   

2. Enter the desired Table name and click on OK:
   

3. And it will open the New Query Window Click on Cancel to close that window and go to Custom Objects Tab.

4. Select the created table, Select Text Type AS SQL and write the your desired SQL Query and Save it and it will create the custom table in the ZappySys Driver:
   Here is an example SQL query for ZappySys Driver. You can insert Placeholders also. Read more about placeholders here
   

   SELECT
     "ShipCountry",
     "OrderID",
     "CustomerID",
     "EmployeeID",
     "OrderDate",
     "RequiredDate",
     "ShippedDate",
     "ShipVia",
     "Freight",
     "ShipName",
     "ShipAddress",
     "ShipCity",
     "ShipRegion",
     "ShipPostalCode"
   FROM "Orders"
   Where "ShipCountry"='USA'

   
   

5. That's it now go to Preview Tab and Execute your custom virtual table query. In this example it will extract the orders for the USA Shipping Country only:
   

   SELECT * FROM "vt__usa_orders_only"

   
   

6. Let's generate the SQL Server Query Code to make the API call using stored procedure. Go to Code Generator Tab, select language as SQL Server and click on Generate button the generate the code.
   As we already created the linked server for this Data Source, in that you just need to copy the Select Query and need to use the linked server name which we have apply on the place of [MY_API_SERVICE] placeholder.
   

   SELECT * FROM OPENQUERY([MY_API_SERVICE], 'EXEC [usp_get_orders] ''1996-01-01''')

   
   

7. Now go to SQL served and execute that query and it will make the API call using stored procedure and provide you the response.
   

Conclusion

In this article we discussed how to connect to Custom API in C# and integrate data without any coding. Click here to Download Custom API Connector for C# and try yourself see how easy it is. If you still have any question(s) then ask here or simply click on live chat icon below and ask our expert (see bottom-right corner of this page).

Download Custom API Connector for C# Documentation 

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Build your own Custom API Connector

Download Custom API Connector for C# Documentation

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