How can I get domain values associated with a field using ArcObjects?

Question

I am trying to access the domain of a selected feature. I have seen examples for VB.NET and C#.NET, but I cannot access the domain of a specified field.

Dim findName As String = Nothing
Dim findValue As Integer = 21 'the domain value for AGRICULTURE
Dim fieldIndex As Integer = m_Feature.Fields.Field("my_field") 'this has a coded domain

'--Check for my_field
If fieldIndex <> -1 Then
    Dim domain As IDomain = m_Feature.Field(fieldIndex).Domain
    If domain.Type = esriDomainType.esriDTCodedValue Then
        Dim cvDomain As ICodedValueDomain2 = TryCast(domain, ICodedValueDomain2)
        For i = 0 To cvDomain.CodeCount - 1
            If cvDomain.Value(i).Equals(findValue) Then
                findName = cvDomain.Name(i)
                Exit For
            End If
        Next i
    End If

When debugging it hangs up on the line with domain.Type, and it shows that the value of Domain is Nothing. The documentation shows that IField.Domain should return the default domain as an IDomain object. I know the field has a domain, but I don't know if it is default and am unable to change it. Does anyone have any advice on how I should access the domain of a field (of a selected feature in my case)?

Answer 1

Thanks to Petr's comments, I found the solution. Below is my functioning code.

Dim findName As String = Nothing
Dim findValue As Integer = 21 'the domain value for AGRICULTURE
Dim fieldIndex As Integer = m_Feature.Fields.Field("my_field") 'this has a coded domain
Dim subfieldIndex As Integer = m_Feature.Fields.FindField("subfield") 'index of subtype field
Dim subfield As Integer = m_Feature.Value(subfieldIndex) 'value of subtype field  

'--Check for my_field
If fieldIndex <> -1 Then

    Dim subtypes As ISubtypes = TryCast(m_Feature.Class, ISubtypes)
    Dim domain As IDomain = subtypes.Domain(subfield, "my_field")

    If domain.Type = esriDomainType.esriDTCodedValue Then
        Dim cvDomain As ICodedValueDomain2 = TryCast(domain, ICodedValueDomain2)
        For i = 0 To cvDomain.CodeCount - 1
            If cvDomain.Value(i).Equals(findValue) Then
                findName = cvDomain.Name(i)
                Exit For
            End If
        Next i
    End If