by Stephen Goguen (2 Submissions)
Category: Databases/Data Access/DAO/ADO
Compatability: VB 6.0
Difficulty: Unknown Difficulty
Originally Published: Thu 14th September 2000
Date Added: Mon 8th February 2021
Rating: 
(1 Votes)
VLRecord - Variable Lookup Record Encapsulates a Collection to behave like a HashTable and Record. Great generic method of copying ADO/DAO
API Declarations
'IMPORTANT: Use 'Tools > Procedure Attributes' to define Item as [Default]
'property.
VBcoders
'AUTHOR: Stephen Goguen
'EMAIL: [email protected]
'CLASS: VLRecord
'DESCRIPTION: Provides the user with a simple Key->Value lookup interface,
'where the user can retrieve and set keys, but cannot enumerate keys or
'values like a hash table.
'EXAMPLE USE:
'Dim George As New Lookup
'Dim Dennis As New Lookup
'
' George("First Name") = "George"
' George("Last Name") = "Wilson"
' George("Age") = 45
' George("Demeanor") = "Irate"
' Dennis("First Name") = "Dennis"
' Dennis("Last Name") = "The Meanace"
' Dennis("Age") = "Young"
' Set Dennis("Target") = George
' Debug.Print Dennis("Target")("First Name") 'Prints George
' Dennis.Remove "Target"
' George.RemoveAll
'NOTES: After reading Advanced Microsoft Visual Basic 5 on the MSDN CD's,
'I rethought using first class data types and using variants instead for
'a number of compelling reasons.
Option Explicit
Dim mKeyLookup As New Collection
'PROPERTY: Get Item
'DESCRIPTION: Retrieves a Variant VALUE given the KEY. If value exists
'for the key Null is returned...
Public Property Get Item(ByVal Key As Variant) As Variant
On Error Resume Next
Key = CStr(Key)
If IsObject(mKeyLookup(Key)) = True Then
Set Item = mKeyLookup(Key)
Else
Item = mKeyLookup(Key)
End If
If IsEmpty(Item) = True Then
Item = Null
End If
End Property
'PROPERTY: Let Item
'DESCRIPTION: Sets the value of a Key for a simple data type.
Public Property Let Item(ByVal Key As Variant, ByVal Value As Variant)
On Error Resume Next
Key = CStr(Key)
mKeyLookup.Add Value, Key
If Err.Number <> 0 Then
mKeyLookup.Remove Key
mKeyLookup.Add Value, Key
End If
End Property
'PROPERTY: Set Item
'DESCRIPTION: Sets the value of a Key for object data types.
Public Property Set Item(ByVal Key As Variant, ByVal Value As Variant)
On Error Resume Next
Key = CStr(Key)
mKeyLookup.Add Value, Key
If Err.Number <> 0 Then
mKeyLookup.Remove Key
mKeyLookup.Add Value, Key
End If
End Property
'FUNCTION: Remove
'DESCRIPTION: Removes a Key->Value pair
Public Function Remove(ByVal Key As Variant)
On Error Resume Next
mKeyLookup.Remove Key
End Function
'FUNCTION: ClearAll
'DESCRIPTION: Removes all Key->Value pairs
Public Function RemoveAll()
Set mKeyLookup = New Collection
End Function
!@#$%^&*(/WARNING/!@#$%^&*
'WARNING!!! - Cut + Paste functions below into seperate module if needed...
'FUNCTION: ReadDAORecord
'DESCRIPTION: Reads from DAO type Recordset to VLRecord
Public Function ReadDAORecord(DAORecordset As DAO.Recordset) As VLRecord
Dim Field As DAO.Field
Dim Record As New VLRecord
For Each Field In DAORecordset.Fields
Record(Field.Name) = Field.Value
Next
Set ReadDAORecord = Record
End Function
'FUNCTION: WriteDAORecord
'DESCRIPTION: Writes record to DAO type recordset
Public Function WriteDAORecord(DAORecordset As DAO.Recordset, Record As VLRecord)
Dim Field As DAO.Field
For Each Field In DAORecordset.Fields
Field.Value = Record(Field.Name)
Next
End Function
'FUNCTION: ReadADORecord
'DESCRIPTION: Read
Public Function ReadADORecord(ADORecordset As ADODB.Recordset) As VLRecord
Dim Field As ADODB.Field
Dim Record As New VLRecord
For Each Field In ADORecordset.Fields
Record(Field.Name) = Field.Value
Next
Set ReadDAORecord = Record
End Function
'FUNCTION: WriteADORecord
'DESCRIPTION: Writes record to ADO type recordset
Public Function WriteADORecord(ADORecordset As ADODB.Recordset, Record As VLRecord)
Dim Field As ADODB.Field
For Each Field In ADORecordset.Fields
Field.Value = Record(Field.Name)
Next
End Function
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