cJson Code Examples

This document contains detailed example code for various practical usage scenarios.

Table of Contents

1. Basic Examples
2. HTTP API Interaction
3. File Operations
4. Complex Data Structures
5. Real Business Scenarios

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Basic Examples

Example 1: Creating a User Info Object

Private Sub CreateUserInfo()
    With New VBMANLIB.cJson
        .Item("username") = "admin"
        .Item("password") = "123456"
        .Item("age") = 40
        .Item("name") = "Deng Wei"

        'Formatted output, display Chinese
        Debug.Print .Encode(, 2, True)
    End With
End Sub

Output:

{
  "username": "admin",
  "password": "123456",
  "age": 40,
  "name": "Deng Wei"
}

Example 2: Creating JSON with an Array

Private Sub CreateWithArray()
    With New VBMANLIB.cJson
        .Item("code") = 200
        .Item("msg") = "Success"

        'Create plain value array
        With .NewItems("hobbies")
            .Items(0) = "Reading"
            .Items(0) = "Swimming"
            .Items(0) = "Coding"
        End With

        Debug.Print .Encode(, 2, True)
    End With
End Sub

Output:

{
  "code": 200,
  "msg": "Success",
  "hobbies": ["Reading", "Swimming", "Coding"]
}

Example 3: Parsing and Reading JSON

Private Sub ParseAndRead()
    Dim JsonText As String
    JsonText = "{""servicesn"":""0001"",""userid"":""admin"",""token"":"""",""argcounts"":2}"

    With New VBMANLIB.cJson
        .Decode JsonText

        'Read fields using Root (recommended approach)
        Debug.Print "Service SN: " & .Root("servicesn")
        Debug.Print "User ID: " & .Root("userid")
        Debug.Print "Token: " & .Root("token")
        Debug.Print "Arg Counts: " & .Root("argcounts")
    End With
End Sub

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HTTP API Interaction

Example 4: Constructing a POST Request Body

Method 1: Using an independent cJson instance (recommended for complex structures)

Private Sub BuildPostBody()
    Dim Body As String

    'Create independent JSON object
    With New cJson
        .Item("sysStuffCode") = "TEST001"
        .Item("quantity") = 2

        'Construct array
        With .NewItems("detailList")
            Dim i As Long
            For i = 0 To 3
                With .NewItem()
                    .Item("test") = 123
                    .Item("time") = Now()
                End With
            Next
        End With

        Body = .Encode()
    End With

    'Send request
    With New cHttpClient
        .RequestHeaders.Add "Content-Type", "application/json"
        .Fetch ReqPost, "https://api.example.com/submit", Body
        Debug.Print .ReturnText()
    End With
End Sub

Method 2: Using HttpClient's built-in RequestDataJson object (concise approach)

Private Sub BuildPostBodySimple()
    With VBMAN.HttpClient
        'Use built-in RequestDataJson object to construct request body
        With .RequestDataJson
            .Clear  'Clear previous data
            .Item("sysStuffCode") = "TEST001"
            .Item("quantity") = 2

            With .NewItems("detailList")
                Dim i As Long
                For i = 0 To 3
                    With .NewItem()
                        .Item("test") = 123
                        .Item("time") = Now()
                    End With
                Next
            End With
        End With

        'Set request type and send (ContentType=Json auto-uses RequestDataJson)
        .SetRequestContentType JsonString
        .SendPost "https://api.example.com/submit"  'Body parameter can be omitted, auto-uses RequestDataJson

        Debug.Print .ReturnText()
    End With
End Sub

Example 5: Handling API Response

Private Sub HandleApiResponse()
    Const API_BASE As String = "https://api.example.com"
    Const API_PULL_WAYBILL As String = API_BASE & "/api/pullWaybill"

    'Construct request data
    Dim Body As String
    With New cJson
        .Item("wayBillId") = "46349936"
        .Item("clientId") = "CLIENT001"
        .Item("token") = "cbe84888-9f48-4c00-aae6-3170bf5951cd"
        Body = .Encode()
    End With

    'Send request and handle response
    On Error GoTo ErrorHandler

    With VBMAN.HttpClient
        .SetRequestContentType JsonString
        .SendPost API_PULL_WAYBILL, Body

        With .ReturnJson()
            'Display full response
            Text2.Text = .Encode(, 2, True)

            'Check business status
            If .Root("success") = True Then
                MsgBox "Cargo Name: " & .Root("data")("cargoName"), , "Waybill No: " & .Root("data")("wayBillId")
            Else
                MsgBox .Root("message"), , "Request Failed"
            End If
        End With
    End With

    Exit Sub

ErrorHandler:
    Debug.Print VBMAN.HttpClient.DebugInfo.Encode(, 2, True)
End Sub

Example 6: Fetching Data with Query Parameters

Private Sub FetchWithQuery()
    Const API_BASE As String = "https://api.example.com"
    Const API_SALE_PLAN As String = API_BASE & "/api/salePlan/selectByVehicleNo"

    On Error Resume Next

    'Use built-in query builder (auto URL-encode)
    VBMAN.HttpClient.RequestDataQuery.Add "vehicleNo", "鲁B70AP0"

    With VBMAN.HttpClient.Fetch(ReqGet, API_SALE_PLAN).ReturnJson()
        'Display formatted result
        Text1.Text = .Encode(, 2, True)

        'Check return status (using Root access)
        If .Root("code") = 200 Then
            'Loop through array
            Dim x As Variant
            For Each x In .Root("data")
                List1.AddItem x("planCode")
                List1.AddItem x("warehouseName")
            Next

            'Directly get specific array object (using Root chained access)
            With .Root("data")(1)
                List1.AddItem .Root("planCode")
                List1.AddItem .Root("warehouseName")
            End With
        Else
            MsgBox .Root("message")
        End If
    End With
End Sub

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File Operations

Example 7: Saving Configuration to a JSON File

Private Sub SaveConfig()
    With VBMAN.Json
        'Clear previous data
        .Clear

        .Item("appName") = "MyApplication"
        .Item("version") = "1.0.0"
        .Item("debug") = True

        'Nested config object
        With .NewItem("database")
            .Item("host") = "localhost"
            .Item("port") = 3306
            .Item("username") = "root"
            .Item("password") = "secret"
        End With

        'Save to file
        .SaveTo App.Path & "\config.json", "UTF-8", 2, True
        MsgBox "Configuration saved"
    End With
End Sub

Example 8: Loading Configuration from a JSON File

Private Sub LoadConfig()
    Dim ConfigPath As String
    ConfigPath = App.Path & "\config.json"

    'Check if file exists
    If Dir(ConfigPath) = "" Then
        MsgBox "Configuration file does not exist"
        Exit Sub
    End If

    With New VBMANLIB.cJson
        .LoadFrom ConfigPath

        'Read configuration
        Dim AppName As String
        Dim DbHost As String
        Dim DbPort As Long

        AppName = .Root("appName")
        DbHost = .Root("database")("host")
        DbPort = .Root("database")("port")

        MsgBox "App: " & AppName & vbCrLf & _
               "Database: " & DbHost & ":" & DbPort
    End With
End Sub

Example 9: Loading from File and Modifying

Private Sub ModifyJsonFile()
    Dim FilePath As String
    FilePath = "C:\tmp\data.json"

    With New VBMANLIB.cJson
        .LoadFrom FilePath

        'Modify data
        .Item("name") = "New Name"
        .Item("updated") = Now()

        'Save back to file
        .SaveTo FilePath, "UTF-8", 2, True
    End With
End Sub

---

Complex Data Structures

Example 10: Unlimited Level Nesting

Private Sub NestedStructure()
    With New VBMANLIB.cJson
        .Item("a") = 1
        .Item("b") = "dengwei"

        With .NewItems("c")
            Dim i As Long
            For i = 0 To 3
                With .NewItem()
                    .Item("d") = Now()
                    .Item("e") = 34 + i
                    .Item("f") = "Data: " & i

                    'Create deeper nesting
                    With .NewItem("g")
                        .Item("g1") = 123
                        .Item("g2") = 456
                    End With

                    With .NewItems("h")
                        .Items(0) = "Array element 1"
                        .Items(0) = "Array element 2"
                    End With
                End With
            Next
        End With

        'Save and display
        .SaveTo "C:\tmp\nested.json", , 2, True
        Text1.Text = .Encode(, 2, True)
    End With
End Sub

Example 11: Mixed Array (Objects and Plain Values)

Private Sub MixedArray()
    With New VBMANLIB.cJson
        'Object array
        With .NewItems("users")
            With .NewItem()
                .Item("name") = "John"
                .Item("age") = 25
            End With
            With .NewItem()
                .Item("name") = "Jane"
                .Item("age") = 30
            End With
        End With

        'Plain value array
        With .NewItems("tags")
            .Items(0) = "VIP"
            .Items(0) = "Active"
            .Items(0) = "Paid"
        End With

        Debug.Print .Encode(, 2, True)
    End With
End Sub

Output:

{
  "users": [
    { "name": "John", "age": 25 },
    { "name": "Jane", "age": 30 }
  ],
  "tags": ["VIP", "Active", "Paid"]
}

Example 12: Parsing Complex Nested JSON

Private Sub ParseComplexNested()
    'Assume this is complex JSON from an API
    Dim JsonText As String
    JsonText = "{"
    JsonText = JsonText & """code"":200,"
    JsonText = JsonText & """data"":{"
    JsonText = JsonText & "  ""company"":""ABC Corp"","
    JsonText = JsonText & "  ""departments"":[{"
    JsonText = JsonText & "    ""name"":""Engineering"","
    JsonText = JsonText & "    ""employees"":[{""name"":""John"",""position"":""Engineer""}]"
    JsonText = JsonText & "  }]"
    JsonText = JsonText & "}"
    JsonText = JsonText & "}"

    With New VBMANLIB.cJson
        .Decode JsonText

        'Deep chained access using Root
        Dim Company As String
        Dim DeptName As String
        Dim EmpName As String

        Company = .Root("data")("company")
        DeptName = .Root("data")("departments")(1)("name")
        EmpName = .Root("data")("departments")(1)("employees")(1)("name")

        MsgBox "Company: " & Company & vbCrLf & _
               "Department: " & DeptName & vbCrLf & _
               "Employee: " & EmpName
    End With
End Sub

---

Real Business Scenarios

Example 13: User Login API (HTTP Server)

'In business class (e.g., bHello.cls)
Public Sub Login(ctx As cHttpServerContext)
    Dim username As String: username = ctx.Request.Form("username")
    Dim password As String: password = ctx.Request.Form("password")

    With New cJson
        .Item("name") = "Deng Wei"
        .Item("age") = 40
        .Item("username") = username
        .Item("password") = password

        'Return formatted JSON
        ctx.Response.Text .Encode(, 2, True)
    End With
End Sub

Example 14: SSE Data Push

'In timed send class (e.g., bSendData.cls)
Private Sub SendTotalData()
    With New VBMANLIB.cJson
        'Server time
        With .NewItem()
            .Item("id") = "serverTime"
            .Item("value") = Format(Now(), "yyyy-MM-dd HH:mm:ss")
        End With

        'Statistics data
        With .NewItem()
            .Item("id") = "today_count"
            .Item("value") = GetTodayCount()
        End With

        With .NewItem()
            .Item("id") = "yesterday_count"
            .Item("value") = GetYesterdayCount()
        End With

        'Send to frontend
        Form1.HttpServer.SSE.SendPack "total", .Encode()
    End With
End Sub

Example 15: Database Records to JSON

Method 1: Using RsToCollection function (Recommended)

VBMAN provides the global function VBMAN.ToolsList.RsToCollection, which can directly convert a Recordset to a Collection. Using it with cJson is simpler:

Private Sub RecordsToJsonEasy()
    Dim Rs As ADODB.Recordset
    Set Rs = GetRecords() 'Get database recordset

    With New VBMANLIB.cJson
        .Item("code") = 200
        .Item("total") = Rs.RecordCount
        'Directly assign converted collection
        .Item("data") = VBMAN.ToolsList.RsToCollection(Rs)

        ctx.Response.Text .Encode(, 2, True)
    End With
End Sub

Method 2: Manual iteration construction (for understanding principles)

Private Sub RecordsToJson()
    Dim Rs As ADODB.Recordset
    Set Rs = GetRecords() 'Get database recordset

    With New VBMANLIB.cJson
        .Item("code") = 200
        .Item("total") = Rs.RecordCount

        With .NewItems("data")
            Do While Not Rs.EOF
                With .NewItem()
                    .Item("id") = Rs("id")
                    .Item("name") = Rs("name")
                    .Item("created") = Rs("created_at")
                End With
                Rs.MoveNext
            Loop
        End With

        'Output or save
        ctx.Response.Text .Encode(, 2, True)
    End With
End Sub

Tip: The RsToCollection function is available globally via VBMAN.ToolsList.RsToCollection. It automatically handles pagination and field mapping, making it the best practice for converting database records to JSON.

Example 16: Batch Task Data Structure

Private Function MakeTaskData() As String
    With New cJson
        'Root is an array, need NewItem first
        With .NewItem()
            .Item("uuid") = GenerateUUID()
            .Item("task_no") = "TASK001"
            .Item("task_type") = 1
            .Item("factory_code") = "0206"
            .Item("warehouse_code") = "0601"

            'Detail array
            With .NewItems("detail")
                With .NewItem()
                    .Item("row_no") = 1
                    .Item("part_no") = "PART001"
                    .Item("qty") = 45.5
                End With
                With .NewItem()
                    .Item("row_no") = 2
                    .Item("part_no") = "PART002"
                    .Item("qty") = 30.0
                End With
            End With
        End With

        MakeTaskData = .Encode(.Root, 2)
    End With
End Function

Example 17: Dynamically Building Report Data

Private Sub BuildReportData()
    With New VBMANLIB.cJson
        .Item("ReportTime") = Format(Date, "yyyy-mm-dd")
        .Item("SampleModel") = "Sample Model 123"
        .Item("ProductModel") = "Product Model ABC"

        Dim i As Long
        For i = 1 To 10
            With .NewItem("record" & i)
                .Item("TestNum") = "TEST" & i
                .Item("T1") = RandValue()
                .Item("T2") = RandValue()
                .Item("Result") = IIf(i Mod 2 = 0, "PASS", "FAIL")
            End With
        Next

        'Save report
        .SaveTo App.Path & "\Reports\" & Format(Now(), "yyyymmdd") & ".json", , 2, True
    End With
End Sub

Example 18: Using Global Instance for Data Caching

Private Sub UseGlobalInstance()
    'Use global VBMAN.Json instance to cache configuration
    With VBMAN.Json
        .Clear 'Clean first

        .Item("api_url") = "https://api.example.com"
        .Item("timeout") = 30
        .Item("retry") = 3

        'Can be used elsewhere directly (Root is default member)
        'MsgBox VBMAN.Json.Root("api_url")
        'Or shorthand:
        'MsgBox VBMAN.Json("api_url")
    End With
End Sub

---

Debug Tips

Example 19: Formatted Output for Debugging

Private Sub DebugJson()
    With New VBMANLIB.cJson
        'Build complex data...
        .Item("data") = "Some data"

        'Output to immediate window (formatted)
        Debug.Print .Encode(, 2, True)

        'Output to text box
        Text1.Text = .Encode(, 2, True)

        'Compact format (for transmission)
        Debug.Print .Encode()
    End With
End Sub

Example 20: Error Handling Pattern

Private Sub SafeParse()
    On Error GoTo ErrorHandler

    Dim Json As New cJson
    Json.Decode Text1.Text

    If Not Json.LastSuccess Then
        MsgBox "JSON parse failed: " & Json.LastError
        Exit Sub
    End If

    'Safe data access
    If Json.RootItem.Exists("name") Then
        MsgBox "Name: " & Json.Item("name")
    Else
        MsgBox "name field does not exist"
    End If

    Exit Sub

ErrorHandler:
    MsgBox "Error occurred: " & Err.Number & " - " & Err.Description
End Sub