ASP.Net: Check if key exists in JSON string using C# and VB.Net

Hi alex0230,

You can use Newtonsoft.Json library.

Parse the JSON string to in Class object and then check with IF condition.

Please refer below sample.

Sample JSON

[
  {
    "id": 180,
    "name": "Microsoft 365",
    "type": {
      "id": 29,
      "name": "Cloud/Hosted Services",
      "_info": { "type_href": "https: //sandbox-na.myconnectwise.net/v4_6_release/apis/3.0//finance/agreements/types/29" }
    },
    "company": {
      "id": 19303,
      "identifier": "AA",
      "name": "Acai Associates",
      "_info": { "company_href": "https://sandbox-na.myconnectwise.net/v4_6_release/apis/3.0//company/companies/19303" }
    },
    "contact": {
      "id": 107,
      "name": "Rafael Oranday",
      "_info": { "contact_href": "https://sandbox-na.myconnectwise.net/v4_6_release/apis/3.0//company/contacts/107" }
    },
    "site": {
      "id": 1095,
      "name": "Main Office",
      "_info": { "site_href": "https://sandbox-na.myconnectwise.net/v4_6_release/apis/3.0//company/companies/19303/sites/1095" }
    },
    "parentAgreement": {
      "id": 1578,
      "name": "Master Services Agreement",
      "_info": { "agreement_href": "https://sandbox-na.myconnectwise.net/v4_6_release/apis/3.0//finance/agreements/1578" }
    },
    "location": {
      "id": 11,
      "name": "Lake Park",
      "_info": { "location_href": "https://sandbox-na.myconnectwise.net/v4_6_release/apis/3.0//system/locations/11" }
    },
    "department": {
      "id": 1,
      "identifier": "Service",
      "name": "Service",
      "_info": { "department_href": "https://sandbox-na.myconnectwise.net/v4_6_release/apis/3.0//system/departments/1" }
    },
    "restrictLocationFlag": false,
    "restrictDepartmentFlag": false,
    "startDate": "2021-12-01T00:00:00Z",
    "noEndingDateFlag": true,
    "cancelledFlag": false,
    "sla": {
      "id": 2,
      "name": "Standard SLA",
      "_info": { "sla_href": "https://sandbox-na.myconnectwise.net/v4_6_release/apis/3.0//service/SLAs/2" }
    },
    "applicationUnits": "Hours",
    "applicationLimit": 0.00,
    "applicationCycle": "CalendarMonth",
    "applicationUnlimitedFlag": true,
    "oneTimeFlag": false,
    "coverAgreementTime": true,
    "coverAgreementProduct": false,
    "coverAgreementExpense": false,
    "coverSalesTax": false,
    "carryOverUnused": false,
    "allowOverruns": false,
    "expireWhenZero": false,
    "chargeToFirm": false,
    "employeeCompRate": "Actual",
    "employeeCompNotExceed": "Billing",
    "compHourlyRate": 0.00,
    "compLimitAmount": 0.00,
    "billingCycle": {
      "id": 2,
      "name": "Monthly"
    },
    "billOneTimeFlag": false,
    "billingTerms": {
      "id": 1,
      "name": "Net 30 days"
    },
    "invoicingCycle": "CalendarYear",
    "billToCompany": {
      "id": 19303,
      "identifier": "AA",
      "name": "Acai Associates",
      "_info": { "company_href": "https://sandbox-na.myconnectwise.net/v4_6_release/apis/3.0//company/companies/19303" }
    },
    "billToContact": {
      "id": 107,
      "name": "Rafael Oranday",
      "_info": { "contact_href": "https://sandbox-na.myconnectwise.net/v4_6_release/apis/3.0//company/contacts/107" }
    },
    "billToSite": {
      "id": 1095,
      "name": "Main Office",
      "_info": { "site_href": "https://sandbox-na.myconnectwise.net/v4_6_release/apis/3.0//company/companies/19303/sites/1095" }
    },
    "billAmount": 0.00,
    "taxable": false,
    "billStartDate": "2022-03-01T00:00:00Z",
    "taxCode": {
      "id": 8,
      "name": "AVATAX",
      "_info": { "taxCode_href": "https://sandbox-na.myconnectwise.net/v4_6_release/apis/3.0//finance/taxCodes/8" }
    },
    "restrictDownPayment": true,
    "prorateFlag": false,
    "topComment": false,
    "bottomComment": false,
    "invoiceTemplate": {
      "id": 10,
      "name": "Monthly Agreement with Location Breakout",
      "_info": { "billingTerms_Href": "https://sandbox-na.myconnectwise.net/v4_6_release/apis/3.0//finance/invoiceTemplateSetups/10" }
    },
    "billTime": "NoDefault",
    "billExpenses": "NoDefault",
    "billProducts": "NoDefault",
    "billableTimeInvoice": false,
    "billableExpenseInvoice": false,
    "billableProductInvoice": false,
    "currency": {
      "id": 7,
      "symbol": "$",
      "currencyCode": "USD",
      "decimalSeparator": ".",
      "numberOfDecimals": 2,
      "thousandsSeparator": ",",
      "negativeParenthesesFlag": false,
      "displaySymbolFlag": true,
      "currencyIdentifier": "USD",
      "displayIdFlag": false,
      "rightAlign": false,
      "name": "US Dollars",
      "_info": { "currency_href": "https://sandbox-na.myconnectwise.net/v4_6_release/apis/3.0//finance/currencies/7" }
    },
    "autoInvoiceFlag": false,
    "nextInvoiceDate": "2022-09-01T00:00:00Z",
    "companyLocation": {
      "id": 18,
      "name": "Small and Medium Business",
      "_info": { "location_href": "https://sandbox-na.myconnectwise.net/v4_6_release/apis/3.0//system/locations/18" }
    },
    "agreementStatus": "Active",
    "_info": {
      "lastUpdated": "2022-01-28T17:07:48Z",
      "updatedBy": "WHough "
    },
    "customFields": [
      {
        "id": 32,
        "caption": "MSA Start Date",
        "type": "Date",
        "entryMethod": "EntryField",
        "numberOfDecimals": 0
      },
      {
        "id": 33,
        "caption": "MSA End Date",
        "type": "Date",
        "entryMethod": "EntryField",
        "numberOfDecimals": 0
      },
      {
        "id": 35,
        "caption": "Contract Sales Person",
        "type": "Text",
        "entryMethod": "EntryField",
        "numberOfDecimals": 0
      }
    ]
  }
]

Code

C#

protected void Page_Load(object sender, EventArgs e)
{
    if (!this.IsPostBack)
    {
        string json = System.IO.File.ReadAllText(Server.MapPath("~/Json.txt"));
        List<Root> roots = Newtonsoft.Json.JsonConvert.DeserializeObject<List<Root>>(json);
        int i = 0;
        foreach (Root root in roots)
        {
            if (root.parentAgreement != null)
            {
                ClientScript.RegisterStartupScript(this.GetType(), "alert" + i, "alert('Parent Agreement exists.');", true);
            }
            else
            {
                ClientScript.RegisterStartupScript(this.GetType(), "alert" + i, "alert('Parent Agreement not exists.');", true);
            }
            i++;
        }
    }
}

public class BillingCycle
{
    public int id { get; set; }
    public string name { get; set; }
}

public class BillingTerms
{
    public int id { get; set; }
    public string name { get; set; }
}

public class BillToCompany
{
    public int id { get; set; }
    public string identifier { get; set; }
    public string name { get; set; }
    public Info _info { get; set; }
}

public class BillToContact
{
    public int id { get; set; }
    public string name { get; set; }
    public Info _info { get; set; }
}

public class BillToSite
{
    public int id { get; set; }
    public string name { get; set; }
    public Info _info { get; set; }
}

public class Company
{
    public int id { get; set; }
    public string identifier { get; set; }
    public string name { get; set; }
    public Info _info { get; set; }
}

public class CompanyLocation
{
    public int id { get; set; }
    public string name { get; set; }
    public Info _info { get; set; }
}

public class Contact
{
    public int id { get; set; }
    public string name { get; set; }
    public Info _info { get; set; }
}

public class Currency
{
    public int id { get; set; }
    public string symbol { get; set; }
    public string currencyCode { get; set; }
    public string decimalSeparator { get; set; }
    public int numberOfDecimals { get; set; }
    public string thousandsSeparator { get; set; }
    public bool negativeParenthesesFlag { get; set; }
    public bool displaySymbolFlag { get; set; }
    public string currencyIdentifier { get; set; }
    public bool displayIdFlag { get; set; }
    public bool rightAlign { get; set; }
    public string name { get; set; }
    public Info _info { get; set; }
}

public class CustomField
{
    public int id { get; set; }
    public string caption { get; set; }
    public string type { get; set; }
    public string entryMethod { get; set; }
    public int numberOfDecimals { get; set; }
    public object value { get; set; }
}

public class Department
{
    public int id { get; set; }
    public string identifier { get; set; }
    public string name { get; set; }
    public Info _info { get; set; }
}

public class Info
{
    public string type_href { get; set; }
    public string contact_href { get; set; }
    public string site_href { get; set; }
    public string taxCode_href { get; set; }
    public string billingTerms_Href { get; set; }
    public string currency_href { get; set; }
    public string location_href { get; set; }
    public DateTime lastUpdated { get; set; }
    public string updatedBy { get; set; }
    public string company_href { get; set; }
    public string agreement_href { get; set; }
    public string department_href { get; set; }
    public string sla_href { get; set; }
}

public class InvoiceTemplate
{
    public int id { get; set; }
    public string name { get; set; }
    public Info _info { get; set; }
}

public class Location
{
    public int id { get; set; }
    public string name { get; set; }
    public Info _info { get; set; }
}

public class ParentAgreement
{
    public int id { get; set; }
    public string name { get; set; }
    public Info _info { get; set; }
}

public class Root
{
    public int id { get; set; }
    public string name { get; set; }
    public Type type { get; set; }
    public Company company { get; set; }
    public Contact contact { get; set; }
    public Site site { get; set; }
    public ParentAgreement parentAgreement { get; set; }
    public Location location { get; set; }
    public Department department { get; set; }
    public bool restrictLocationFlag { get; set; }
    public bool restrictDepartmentFlag { get; set; }
    public DateTime startDate { get; set; }
    public bool noEndingDateFlag { get; set; }
    public bool cancelledFlag { get; set; }
    public Sla sla { get; set; }
    public string applicationUnits { get; set; }
    public double applicationLimit { get; set; }
    public string applicationCycle { get; set; }
    public bool applicationUnlimitedFlag { get; set; }
    public bool oneTimeFlag { get; set; }
    public bool coverAgreementTime { get; set; }
    public bool coverAgreementProduct { get; set; }
    public bool coverAgreementExpense { get; set; }
    public bool coverSalesTax { get; set; }
    public bool carryOverUnused { get; set; }
    public bool allowOverruns { get; set; }
    public bool expireWhenZero { get; set; }
    public bool chargeToFirm { get; set; }
    public string employeeCompRate { get; set; }
    public string employeeCompNotExceed { get; set; }
    public double compHourlyRate { get; set; }
    public double compLimitAmount { get; set; }
    public BillingCycle billingCycle { get; set; }
    public bool billOneTimeFlag { get; set; }
    public BillingTerms billingTerms { get; set; }
    public string invoicingCycle { get; set; }
    public BillToCompany billToCompany { get; set; }
    public BillToContact billToContact { get; set; }
    public BillToSite billToSite { get; set; }
    public double billAmount { get; set; }
    public bool taxable { get; set; }
    public DateTime billStartDate { get; set; }
    public TaxCode taxCode { get; set; }
    public bool restrictDownPayment { get; set; }
    public bool prorateFlag { get; set; }
    public bool topComment { get; set; }
    public bool bottomComment { get; set; }
    public InvoiceTemplate invoiceTemplate { get; set; }
    public string billTime { get; set; }
    public string billExpenses { get; set; }
    public string billProducts { get; set; }
    public bool billableTimeInvoice { get; set; }
    public bool billableExpenseInvoice { get; set; }
    public bool billableProductInvoice { get; set; }
    public Currency currency { get; set; }
    public bool autoInvoiceFlag { get; set; }
    public DateTime nextInvoiceDate { get; set; }
    public CompanyLocation companyLocation { get; set; }
    public string agreementStatus { get; set; }
    public Info _info { get; set; }
    public List<CustomField> customFields { get; set; }
    public string invoiceDescription { get; set; }
}

public class Site
{
    public int id { get; set; }
    public string name { get; set; }
    public Info _info { get; set; }
}

public class Sla
{
    public int id { get; set; }
    public string name { get; set; }
    public Info _info { get; set; }
}

public class TaxCode
{
    public int id { get; set; }
    public string name { get; set; }
    public Info _info { get; set; }
}

public class Type
{
    public int id { get; set; }
    public string name { get; set; }
    public Info _info { get; set; }
}

VB.Net

Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs) Handles Me.Load
    If Not Me.IsPostBack Then
        Dim json As String = System.IO.File.ReadAllText(Server.MapPath("~/Json.txt"))
        Dim roots As List(Of Root) = Newtonsoft.Json.JsonConvert.DeserializeObject(Of List(Of Root))(json)
        Dim i As Integer = 0
        For Each root As Root In roots
            If root.parentAgreement IsNot Nothing Then
                ClientScript.RegisterStartupScript(Me.GetType(), "alert" & i, "alert('Parent Agreement exists.');", True)
            Else
                ClientScript.RegisterStartupScript(Me.GetType(), "alert" & i, "alert('Parent Agreement not exists.');", True)
            End If
            i += 1
        Next
    End If
End Sub

Public Class BillingCycle
    Public Property id As Integer
    Public Property name As String
End Class

Public Class BillingTerms
    Public Property id As Integer
    Public Property name As String
End Class

Public Class BillToCompany
    Public Property id As Integer
    Public Property identifier As String
    Public Property name As String
    Public Property _info As Info
End Class

Public Class BillToContact
    Public Property id As Integer
    Public Property name As String
    Public Property _info As Info
End Class

Public Class BillToSite
    Public Property id As Integer
    Public Property name As String
    Public Property _info As Info
End Class

Public Class Company
    Public Property id As Integer
    Public Property identifier As String
    Public Property name As String
    Public Property _info As Info
End Class

Public Class CompanyLocation
    Public Property id As Integer
    Public Property name As String
    Public Property _info As Info
End Class

Public Class Contact
    Public Property id As Integer
    Public Property name As String
    Public Property _info As Info
End Class

Public Class Currency
    Public Property id As Integer
    Public Property symbol As String
    Public Property currencyCode As String
    Public Property decimalSeparator As String
    Public Property numberOfDecimals As Integer
    Public Property thousandsSeparator As String
    Public Property negativeParenthesesFlag As Boolean
    Public Property displaySymbolFlag As Boolean
    Public Property currencyIdentifier As String
    Public Property displayIdFlag As Boolean
    Public Property rightAlign As Boolean
    Public Property name As String
    Public Property _info As Info
End Class

Public Class CustomField
    Public Property id As Integer
    Public Property caption As String
    Public Property type As String
    Public Property entryMethod As String
    Public Property numberOfDecimals As Integer
    Public Property value As Object
End Class

Public Class Department
    Public Property id As Integer
    Public Property identifier As String
    Public Property name As String
    Public Property _info As Info
End Class

Public Class Info
    Public Property type_href As String
    Public Property contact_href As String
    Public Property site_href As String
    Public Property taxCode_href As String
    Public Property billingTerms_Href As String
    Public Property currency_href As String
    Public Property location_href As String
    Public Property lastUpdated As DateTime
    Public Property updatedBy As String
    Public Property company_href As String
    Public Property agreement_href As String
    Public Property department_href As String
    Public Property sla_href As String
End Class

Public Class InvoiceTemplate
    Public Property id As Integer
    Public Property name As String
    Public Property _info As Info
End Class

Public Class Location
    Public Property id As Integer
    Public Property name As String
    Public Property _info As Info
End Class

Public Class ParentAgreement
    Public Property id As Integer
    Public Property name As String
    Public Property _info As Info
End Class

Public Class Root
    Public Property id As Integer
    Public Property name As String
    Public Property type As Type
    Public Property company As Company
    Public Property contact As Contact
    Public Property site As Site
    Public Property parentAgreement As ParentAgreement
    Public Property location As Location
    Public Property department As Department
    Public Property restrictLocationFlag As Boolean
    Public Property restrictDepartmentFlag As Boolean
    Public Property startDate As DateTime
    Public Property noEndingDateFlag As Boolean
    Public Property cancelledFlag As Boolean
    Public Property sla As Sla
    Public Property applicationUnits As String
    Public Property applicationLimit As Double
    Public Property applicationCycle As String
    Public Property applicationUnlimitedFlag As Boolean
    Public Property oneTimeFlag As Boolean
    Public Property coverAgreementTime As Boolean
    Public Property coverAgreementProduct As Boolean
    Public Property coverAgreementExpense As Boolean
    Public Property coverSalesTax As Boolean
    Public Property carryOverUnused As Boolean
    Public Property allowOverruns As Boolean
    Public Property expireWhenZero As Boolean
    Public Property chargeToFirm As Boolean
    Public Property employeeCompRate As String
    Public Property employeeCompNotExceed As String
    Public Property compHourlyRate As Double
    Public Property compLimitAmount As Double
    Public Property billingCycle As BillingCycle
    Public Property billOneTimeFlag As Boolean
    Public Property billingTerms As BillingTerms
    Public Property invoicingCycle As String
    Public Property billToCompany As BillToCompany
    Public Property billToContact As BillToContact
    Public Property billToSite As BillToSite
    Public Property billAmount As Double
    Public Property taxable As Boolean
    Public Property billStartDate As DateTime
    Public Property taxCode As TaxCode
    Public Property restrictDownPayment As Boolean
    Public Property prorateFlag As Boolean
    Public Property topComment As Boolean
    Public Property bottomComment As Boolean
    Public Property invoiceTemplate As InvoiceTemplate
    Public Property billTime As String
    Public Property billExpenses As String
    Public Property billProducts As String
    Public Property billableTimeInvoice As Boolean
    Public Property billableExpenseInvoice As Boolean
    Public Property billableProductInvoice As Boolean
    Public Property currency As Currency
    Public Property autoInvoiceFlag As Boolean
    Public Property nextInvoiceDate As DateTime
    Public Property companyLocation As CompanyLocation
    Public Property agreementStatus As String
    Public Property _info As Info
    Public Property customFields As List(Of CustomField)
    Public Property invoiceDescription As String
End Class

Public Class Site
    Public Property id As Integer
    Public Property name As String
    Public Property _info As Info
End Class

Public Class Sla
    Public Property id As Integer
    Public Property name As String
    Public Property _info As Info
End Class

Public Class TaxCode
    Public Property id As Integer
    Public Property name As String
    Public Property _info As Info
End Class

Public Class Type
    Public Property id As Integer
    Public Property name As String
    Public Property _info As Info
End Class

Screenshot