How To Call Rest Api From Vba Using Vba

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How to Call REST API from VBA using VBA

Calling a REST API from VBA (Visual Basic for Applications) can be a useful feature when automating tasks or integrating different systems. Here’s a step-by-step guide with detailed explanations and examples:

Step 1: Enable Microsoft XML, v6.0 (MSXML2) Library

In order to make HTTP requests and handle XML or JSON responses, you need to enable the Microsoft XML, v6.0 library in your VBA project. To do this, follow these steps:

  1. Open the Visual Basic for Applications editor in your application (e.g., Microsoft Excel).
  2. Click on the “Tools” menu and select “References”.
  3. In the References dialog, find and check the “Microsoft XML, v6.0” option.
  4. Click “OK” to save the changes and close the dialog.

Step 2: Create a Function for Making HTTP GET Requests

To call a REST API endpoint using VBA, you can create a function that makes an HTTP GET request. Here’s an example of such a function:

Function CallRestApi(url As String) As String
    Dim xmlHttp As Object
    Set xmlHttp = CreateObject("MSXML2.XMLHTTP")

    ' Make the HTTP request
    xmlHttp.Open "GET", url, False
    xmlHttp.setRequestHeader "Content-Type", "application/json"
    xmlHttp.send

    ' Get the response from the API
    CallRestApi = xmlHttp.responseText
End Function

In this example, the function takes the URL of the REST API endpoint as an input parameter. It creates an instance of the XMLHTTP object and makes an HTTP GET request to the specified URL. The response from the API is returned as a string.

Step 3: Call the Function with the API Endpoint URL

Once you have the function defined, you can call it with the URL of the REST API endpoint you want to access. Here’s an example of calling the function and printing the response:

Sub AccessRestApi()
    Dim apiUrl As String
    Dim response As String
    
    ' Set the API endpoint URL
    apiUrl = "https://api.example.com/users"
    
    ' Call the REST API function
    response = CallRestApi(apiUrl)

    ' Print the response
    Debug.Print response
End Sub

In this example, the “AccessRestApi” subroutine sets the API endpoint URL, calls the “CallRestApi” function with the URL, and prints the response to the debugging console.

Step 4: Handle the API Response

Depending on the specific API you are calling, the response can be in XML or JSON format. You can use VBA’s built-in functions or libraries like JSONConverter to parse and extract the required data from the response. Here’s an example of handling a JSON response using the VBA-JSON library:

Sub HandleApiResponse()
    Dim apiUrl As String
    Dim response As String
    Dim json As Object
    
    ' Set the API endpoint URL
    apiUrl = "https://api.example.com/users"
    
    ' Call the REST API function
    response = CallRestApi(apiUrl)

    ' Parse the JSON response
    Set json = JsonConverter.ParseJson(response)

    ' Extract data from the JSON response
    Debug.Print json("name")
    Debug.Print json("email")
End Sub

In this example, the “HandleApiResponse” subroutine sets the API endpoint URL, calls the “CallRestApi” function to get the response, and uses the JsonConverter library to parse the JSON response. It then extracts and prints the values of the “name” and “email” fields from the JSON.

Conclusion

By following these steps and examples, you can easily call a REST API from VBA using VBA. Remember to enable the necessary library, create a function for making HTTP requests, call the function with the API endpoint URL, and handle the API response based on the format (XML or JSON).

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