VBA JSON Formatting Solutions for Office Automation

Visual Basic for Applications (VBA) remains a powerful tool for automating tasks within Microsoft Office applications like Excel, Word, and Access. However, modern workflows often involve interacting with web services and APIs, which predominantly use JSON (JavaScript Object Notation) as their data interchange format. This presents a challenge, as VBA lacks native built-in functions for parsing or formatting JSON.

The Core Problem: VBA's Missing JSON Support

Unlike many modern programming languages (Python, JavaScript, C#, etc.) that have standard libraries for JSON manipulation, VBA does not. If you receive a JSON string from a web request or need to generate a JSON string to send to an API, you cannot simply call a function like `JSON.parse()` or `JSON.stringify()` as you would in JavaScript. You need alternative strategies to work with this common data format.

Representing JSON Data in VBA

Before parsing or formatting, it's helpful to understand how JSON data structures map to VBA concepts:

• JSON Object ({} ): Key-value pairs. In VBA, this is best represented by a Dictionary object from theMicrosoft Scripting Runtime library. Keys are typically strings, and values can be any VBA data type, including other Dictionaries or Collections.
• JSON Array ([] ): An ordered list of values. In VBA, this can be represented by a Collection or, more efficiently, an ArrayList from theMicrosoft Scripting Runtime library. Elements can be of different types.
• JSON Values (String, Number, Boolean, Null): These map directly to VBA data types like String, Double(or Long), Boolean, and the special valueNull.

To use Dictionary and ArrayList, you need to add a reference in your VBA project (Tools > References) toMicrosoft Scripting Runtime.

Example: Mapping JSON to VBA Objects

Conceptually, a JSON object like {{ "name": "Alice", "age": 30 }}would become a VBA Dictionary:

' Requires reference: Microsoft Scripting Runtime
Dim personDict As New Scripting.Dictionary
personDict.Add "name", "Alice"
personDict.Add "age", 30

' Accessing data
Dim personName As String
personName = personDict("name") ' Access by key

' Similar for Arrays (using Collection or ArrayList)
Dim hobbiesList As New Collection ' Or Scripting.ArrayList
hobbiesList.Add "Reading"
hobbiesList.Add "Hiking"

' A more complex example (nested)
Dim complexObj As New Scripting.Dictionary
Dim addressDict As New Scripting.Dictionary
addressDict.Add "city", "London"
addressDict.Add "zip", "SW1A 0AA"
complexObj.Add "address", addressDict

' Accessing nested data
Dim city As String
city = complexObj("address")("city")

Building these structures manually in VBA is feasible but quickly becomes tedious for complex JSON. This is where parsing comes in.

Parsing JSON (String to VBA Objects)

Parsing involves taking a raw JSON string and converting it into a usable VBA data structure (like nested Dictionaries and Collections/ArrayLists). The most common and practical approaches involve using external VBA libraries.

Solution 1: Using an External VBA JSON Parser Library

Several developers have created open-source VBA projects specifically for JSON parsing and serialization. The most popular and well-regarded is often referred to as the "VBA-JSON" parser (available on GitHub, look for "VBA-JSON").

To use such a library, you typically download the provided .basor .cls files and import them into your VBA project. These libraries provide functions like JsonConverter.ParseJson.

' Assume JsonConverter module is imported
Dim jsonString As String
jsonString = "{ ""id"": 101, ""active"": True, ""tags"": [""api"", ""data""] }"

Dim parsedData As Object ' Can be Dictionary or Collection/ArrayList depending on root
Set parsedData = JsonConverter.ParseJson(jsonString)

' Accessing parsed data (requires knowing the structure)
Dim itemId As Long
itemId = parsedData("id")

Dim firstTag As String
' JsonConverter often uses Collections for arrays by default
firstTag = parsedData("tags")(1) ' Collections are 1-indexed

' Check boolean
Dim isActive As Boolean
isActive = parsedData("active")

Advantages: Relatively easy to use, handles complex structures, robust, widely tested.

Disadvantages: Requires importing external code into your project, potential dependency management (though usually just copying files).

Solution 2: Manual Parsing (Not Recommended for Complexity)

It is theoretically possible to write your own VBA code to parse JSON by iterating through the string, looking for ` , ` , `[` , `]` , `:` , `,` , quotes, etc., and building the `Dictionary`/`Collection` structures. However, this is extremely complex, error-prone, and difficult to maintain, especially when dealing with nested structures, escaped characters within strings, and various data types. For almost all practical purposes, using a dedicated library is preferred.

Serializing JSON (VBA Objects to String)

Serialization is the reverse process: taking VBA data (Dictionaries, Collections/ArrayLists, simple types) and converting it into a valid JSON string.

Solution 1: Using an External VBA JSON Parser Library

Libraries like "VBA-JSON" also provide functions for serialization, typically something like JsonConverter.ConvertToJson.

' Assume JsonConverter module is imported and projectData is defined
Dim projectData As New Scripting.Dictionary
projectData.Add "name", "Office Report"
projectData.Add "version", 1.5
projectData.Add "isComplete", False

Dim authorsList As New Collection
authorsList.Add "Bob"
authorsList.Add "Charlie"
projectData.Add "authors", authorsList

' Convert VBA structure to JSON string
Dim jsonOutputString As String
Set jsonOutputString = JsonConverter.ConvertToJson(projectData)

' jsonOutputString will now contain:
' {"name":"Office Report","version":1.5,"isComplete":false,"authors":["Bob","Charlie"]}

Advantages: Handles nesting and data types correctly, simplifies the process significantly.

Disadvantages: Same as parsing - requires importing external code.

Solution 2: Manual Serialization (Complex)

Similar to parsing, you could write VBA code to manually iterate through Dictionaries and Collections, appending strings, managing commas, quotes, colons, brackets, and handling nested structures recursively. This is also very complex and error-prone, especially dealing with escaping special characters within strings. Use a library if possible.

Formatting / Pretty-Printing JSON

Sometimes you receive a compact JSON string with no indentation or line breaks, making it hard to read. "Formatting" or "Pretty-Printing" adds whitespace to make the structure clear.

Method 1: Using Library Options

Some JSON libraries (like "VBA-JSON") offer an optional argument during serialization to produce pretty-printed output.

' Assume JsonConverter module is imported and projectData is defined
Dim prettyJsonString As String
' Check library documentation for exact parameter name/value
Set prettyJsonString = JsonConverter.ConvertToJson(projectData, "", True) ' Assuming last param is 'Indent'

' prettyJsonString might now contain:
' {
'   "name": "Office Report",
'   "version": 1.5,
'   "isComplete": false,
'   "authors": [
'     "Bob",
'     "Charlie"
'   ]
' }

This is the easiest method if your chosen library supports it.

Method 2: Implementing a Basic Pretty-Printer in VBA

If you only need to format an existing JSON string and don't want a full parser library, or if your library doesn't support pretty-printing, you can write VBA code to do this. The core logic involves iterating through the string character by character, keeping track of the current indentation level.

Here's the basic algorithm concept:

1. Initialize an empty output string and an indent level counter (start at 0).
2. Initialize an indent string (e.g., 4 spaces or a tab).
3. Iterate through the input JSON string character by character.
4. Append the current character to the output string.
5. Handle special characters:
   • If you see { or [, increment the indent level. If the *next* character is not } or ], add a newline and append the current indent (indent level * indent string) to the output.
   • If you see } or ], decrement the indent level *before* appending the character. If the *previous* character was not { or [, add a newline *before* appending the character, then append the current indent.
   • If you see ',', append the comma, then add a newline and append the current indent.
   • Be careful inside strings (`"..."`) - don't apply formatting rules to characters within quotes. You need to track whether you are currently inside a string.
6. Manage the indent based on the level.

Implementing this correctly requires careful handling of states (inside string, after colon, etc.) and edge cases (empty objects/arrays, trailing commas - though trailing commas are not standard JSON). It's more involved than it might first appear, but simpler than full parsing/serialization.

Many examples of VBA JSON formatters can be found online if you search for "VBA JSON pretty print function".

Fetching JSON Data in VBA (HTTP Requests)

Often, the need for JSON formatting comes from fetching data from a web API. VBA can make HTTP requests using the MSXML2.XMLHTTP object.

' Requires reference: Microsoft XML, v6.0 (or similar)
Dim xmlHttp As MSXML2.XMLHTTP60 ' Use the highest version available
Dim apiUrl As String
Dim jsonResponse As String

apiUrl = "https://jsonplaceholder.typicode.com/posts/1" ' Example API endpoint

Set xmlHttp = New MSXML2.XMLHTTP60

xmlHttp.Open "GET", apiUrl, False ' False makes it synchronous
xmlHttp.send

If xmlHttp.status = 200 Then ' Check for successful HTTP status
    jsonResponse = xmlHttp.responseText
    MsgBox "Received JSON: " & jsonResponse
    ' Now you would pass jsonResponse to your JSON parser
Else
    MsgBox "Error fetching data: " & xmlHttp.status & " - " & xmlHttp.statusText
End If

Set xmlHttp = Nothing

After fetching the jsonResponse string, you would then use one of the parsing methods discussed earlier to convert it into a usable VBA data structure.

Choosing the Right Solution

• For complex JSON parsing or serialization: Use a robust external VBA JSON library like "VBA-JSON". This is by far the most efficient and reliable method.
• For simple structures or if external libraries are strictly forbidden:You might manually map using Dictionaries and Collections/ArrayLists, but avoid manual string parsing/serialization for anything but the most trivial cases.
• For just pretty-printing an existing string: Check if your chosen library has a pretty-print option. If not, a dedicated VBA pretty-printer function (search online for examples) is a reasonable alternative to a full parser library if you only need formatting.
• For fetching JSON from APIs: Use the MSXML2.XMLHTTPobject.

Conclusion

While VBA doesn't offer native JSON handling, integrating JSON into Office automation workflows is achievable and common. By leveraging the `Microsoft Scripting Runtime` for data representation and, most importantly, incorporating well-developed external VBA JSON libraries for parsing and serialization, developers can seamlessly exchange data between Office applications and modern web services. Understanding these solutions empowers you to build more dynamic and connected Office automation tools.