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'Represents a single migration (either up or down)
Class Migration_Class
Private m_name
Private m_migration_instance
Private m_sql_array
Private m_sql_array_size
Private m_connection
Private m_has_errors
Public Tracing 'bool
Public Property Get Name
Name = m_name
End Property
Public Property Get Migration
set Migration = m_migration_instance
End Property
Public Property Set Migration(obj)
set m_migration_instance = obj
End Property
Public Property Get HasErrors
HasErrors = m_has_errors
End Property
Private Sub Class_Initialize
m_sql_array = array()
redim m_sql_array(-1)
m_has_errors = false
End Sub
Public Sub Initialize(name, migration_instance, connection)
m_name = name
set m_migration_instance = migration_instance
set m_migration_instance.Migration = Me 'how circular can we get? ...
set m_connection = connection
End Sub
Private Sub Class_Terminate
'm_connection.Close
'set m_connection = Nothing
End Sub
Public Sub [Do](sql)
dim new_size : new_size = ubound(m_sql_array) + 1
redim preserve m_sql_array(new_size)
m_sql_array(new_size) = sql
'put "Added command: " & sql
End Sub
Public Sub Irreversible
Err.Raise 1, "Migration_Class:Irreversible", "Migration cannot proceed because this migration is irreversible."
End Sub
Public Sub DownDataWarning
put "Migration can be downversioned but data changes cannot take place due to the nature of the Up migration in this set."
End Sub
Public Function Query(sql)
put "Query: " & sql
set Query = m_connection.Execute(sql)
End Function
Public Sub DoUp
Migration.Up
ShowCommands
ExecuteCommands
End Sub
Public Sub DoDown
Migration.Down
ShowCommands
ExecuteCommands
End Sub
Private Sub ShowCommands
put ""
put "Commands:"
dim i : i = 0
For i = 0 to ubound(m_sql_array)
put " Command: " & m_sql_array(i)
Next
put ""
End Sub
Private Sub ExecuteCommands
dim i : i = 0
dim sql
m_connection.BeginTrans 'wrap entire process in transaction, rollback If error encountered on any statement
For i = 0 to ubound(m_sql_array)
sql = m_sql_array(i)
If not m_has_errors then 'avoid further processing If errors exist
On Error Resume Next
put "Executing: " & sql
m_connection.Execute sql
If Err.Number <> 0 then 'something went wrong, rollback the transaction and display an error
m_has_errors = true
m_connection.RollbackTrans
put_error "Error during migration: " & Err.Description
put_error "SQL: " & sql
exit sub
End If
On Error Goto 0
End If
Next
m_connection.CommitTrans 'surprisingly no errors were encountered, so commit the entire transaction
End Sub
'force font color dIfference
Private Sub put(s)
If Me.Tracing then response.write "<div style='color: #999'>" & s & "</div>"
End Sub
End Class
'---------------------------------------------------------------------------------------------------------------------
'Represents the collection of migrations to be performed
Class Migrations_Class
Private m_migrations_array ' 1-based to match migration naming scheme, ignore the first element
Private m_migrations_array_size
Private m_version
Private m_connection
Private m_connection_string
Private m_has_errors
Public Tracing 'bool
Private Sub Class_Initialize
m_migrations_array = array()
m_migrations_array_size = 0 ' 1-based, ignore the first element
redim m_migrations_array(m_migrations_array_size)
m_has_errors = false
End Sub
Private Sub Class_Terminate
On Error Resume Next
m_connection.Close
set m_connection = Nothing
On Error Goto 0
End Sub
'force font color dIfference
Private Sub put(s)
If Me.Tracing then response.write "<div style='color: #999'>" & s & "</div>"
End Sub
Public Sub Initialize(connection_string)
m_connection_string = connection_string
set m_connection = Server.CreateObject("ADODB.Connection")
m_connection.Open m_connection_string
put "Initialized: " & typename(m_connection)
End Sub
Public Sub Add(name)
m_migrations_array_size = m_migrations_array_size + 1
redim preserve m_migrations_array(m_migrations_array_size)
dim M : set M = new Migration_Class
dim migration_instance : set migration_instance = eval("new " & name)
M.Initialize name, migration_instance, m_connection
M.Tracing = Me.Tracing
set m_migrations_array(m_migrations_array_size) = M
End Sub
Public Sub MigrateUp
MigrateUpTo m_migrations_array_size
End Sub
Public Sub MigrateUpBy(num)
MigrateUpTo Version + num
End Sub
Public Sub MigrateUpTo(requested_version)
requested_version = CInt(requested_version)
put "Migrating Up To Version " & requested_version
dim M, class_name
If Version >= requested_version then
put_error "DB already at higher version than requested up migration."
ElseIf requested_version > m_migrations_array_size then
put_error "Requested version exceeds available migrations. Only " & m_migrations_array_size & " migrations are available."
Else
While (NextVersion <= requested_version) and (not m_has_errors)
set M = m_migrations_array(NextVersion)
put ""
put "<b>Up: " & M.name & "</b>"
M.DoUp
m_has_errors = M.HasErrors
If not m_has_errors then IncrementVersion
Wend
End If
End Sub
Public Sub MigrateDown
MigrateDownTo 0
End Sub
Public Sub MigrateDownBy(num)
MigrateDownTo Version - num
End Sub
Public Sub MigrateDownTo(requested_version)
requested_version = CInt(requested_version)
put "Migrating Down To Version: " & requested_version
dim M, class_name
If requested_version < 0 then
put_error "Cannot migrate down to a version less than 0."
ElseIf requested_version > Version then
put_error "Cannot migrate down to a version higher than the current version."
ElseIf requested_version = Version then
put_error "Cannot migrate down to the current version, already there."
Else
While (Version > requested_version) and (not m_has_errors)
set M = m_migrations_array(Version)
put ""
put "<b>Down: " & M.Name & "</b>"
M.DoDown
m_has_errors = M.HasErrors
If not m_has_errors then DecrementVersion
Wend
End If
End Sub
Public Property Get Version
If IsEmpty(m_version) then
m_version = GetDBVersion()
End If
Version = m_version
End Property
Private Property Let Version(val)
m_version = val
m_connection.Execute "update meta_migrations set version = " & m_version
End Property
Public Property Get NextVersion
NextVersion = Version + 1
End Property
Private Function GetDBVersion()
dim rs : set rs = m_connection.Execute("select version from meta_migrations")
If rs.BOF or rs.EOF then
GetDBVersion = NULL
Else
GetDBVersion = rs("version")
End If
rs.Close
set rs = Nothing
End Function
Private Sub IncrementVersion
If not m_has_errors then Version = Version + 1
End Sub
Private Sub DecrementVersion
If not m_has_errors then Version = Version - 1
End Sub
End Class
dim Migrations_Class__Singleton
Function Migrations()
If IsEmpty(Migrations_Class__Singleton) then set Migrations_Class__Singleton = new Migrations_Class
set Migrations = Migrations_Class__Singleton
End Function
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