No I didn't mean that. ToXML() parameter does that.
Cetin
>The IsDiffGram causes only changes to be sent to the XML file?
>
>
>
>>Kevin,
>>I don't know really. Probably it means attached XML stays as is but only the ToXML(...,lChangesOnly) outputs diffgram.
>>Cetin
>>
>>>Thanks! This example is exactly what I was looking for.
>>>
>>>The help file says "Setting the IsDiffGram property does not actually
>>>alter the associated XML document."
>>>
>>>I'm not sure I understand this property. Can you elaborate?
>>>
>>>Thanks Cetin!
>>>
>>>
>>>
>>>
>>>>Yes and no. Depends on version. Under VFP9 you have the luxury doing this with XMLAdpater class. The diffgram I pasted is from VFP7. Here is a sample for VFP9 that both creates the diffgram (might be your COM1) and updates from XML diffgram (might be your COM2):
>>>>
>>>>LOCAL lcDiffXML
>>>>lcDiffXML = GetDiffGram()
>>>>UpdateFromDiffgram(m.lcDiffXML)
>>>>
>>>>
>>>>PROCEDURE GetDiffGram
>>>>USE _samples+"\data\customer"
>>>>CURSORSETPROP("Buffering",5,'customer')
>>>>BROWSE TITLE "Modify on site 1"
>>>>
>>>>* Create diffgram xml
>>>>LOCAL lcChanges, oAdapter
>>>>oAdapter = CREATEOBJECT('xmlAdapter')
>>>>oAdapter.AddTableSchema('customer')
>>>>oAdapter.IsDiffgram = .T.
>>>>oAdapter.ToXML('lcChanges','',.f.,.t.,.t.)
>>>>* Closing data just for sampling
>>>>USE IN 'customer'
>>>>RETURN m.lcChanges
>>>>
>>>>PROCEDURE UpdateFromDiffgram(tcDiffGram)
>>>>LOCAL oAdapter
>>>>* just for sampling using a different alias
>>>>USE _samples+'data\customer' ALIAS myCustomer
>>>>* we don't want to save when we are sampling only
>>>>CURSORSETPROP("Buffering",5,'myCustomer')
>>>>BROWSE TITLE 'Before applying diffgram'
>>>>
>>>>oAdapter = CREATEOBJECT('xmlAdapter')
>>>>oAdapter.LoadXML(m.tcDiffGram,.f.)
>>>>oAdapter.Tables(1).Alias = 'myCustomer'
>>>>oAdapter.Tables(1).ApplyDiffgram()
>>>>BROWSE TITLE 'After applying diffgram'
>>>>Too much hardcoding in there but this is a sample:)
>>>>PS: AFAIK you also work with .Net and you would like to know XMLAdapter is friendly with .Net datasets and diffgrams (also VFPOLEDB have as added support).
>>>>Cetin
>>>>
>>>>>Do I understand that I must store the changes back to the database myself? How is this
>>>>>done? There could be any number of records and field changed. Is there any way to do
>>>>>this automatically?
>>>>>
>>>>>
>>>>>
>>>>>>XmlUpdateGram() function creates an updategram (needs multilocks and buffering). That is it only includes updated/inserted/deleted records as updgram:before and after records. Suppose you updated customer table and changed company field, deleted ANATR and inserted NEWCUS. XmlUpdateGram('customer') produces an output like:
>>>>>>
>>>>>><?xml version = "1.0" encoding="Windows-1252" standalone="yes"?>
>>>>>><root xmlns:updg="urn:schemas-microsoft-com:xml-updategram">
>>>>>> <updg:sync>
>>>>>> <updg:before>
>>>>>> <customer>
>>>>>> <cust_id>ALFKI</cust_id>
>>>>>> <company>Alfreds Futterkiste</company>
>>>>>>* other fields here
>>>>>> </customer>
>>>>>> </updg:before>
>>>>>> <updg:after>
>>>>>> <customer>
>>>>>> <cust_id>ALFKI</cust_id>
>>>>>> <company>Alfreds Futterkiste-Updated</company>
>>>>>>* other fields here
>>>>>> </customer>
>>>>>> </updg:after>
>>>>>> <updg:before>
>>>>>> <customer>
>>>>>>* all fields here - unmodified
>>>>>> </customer>
>>>>>> </updg:before>
>>>>>> <updg:after/>
>>>>>> <updg:before/>
>>>>>> <updg:after>
>>>>>> <customer>
>>>>>> <cust_id>NEWCUS</cust_id>
>>>>>>* other fields here
>>>>>> </customer>
>>>>>> </updg:after>
>>>>>> </updg:sync>
>>>>>></root>
>>>>>>
Instead of receiving the whole table diffgram approach only gets 'differences' IOW. On receving side you have to process this yourself however (ie: XMLDocument). VFP9 CA and XMLAdapter might help you to work with them in an easier way. Check
www.prenia.com for samples.
>>>>>>Cetin
>>>>>>
>>>>>>
>>>>>>>The reason I'm using COM is because I will need to update the
>>>>>>>application piece by piece. I don't want everything compiled
>>>>>>>into one big EXE.
>>>>>>>
>>>>>>>Can you elaborate on the DiffGram option?
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>>Hmm that in turn would bring up other questions. Ways to go are more than one and which one to choose depends. ie: One scenario:
>>>>>>>>
>>>>>>>>Instead of CursorToXml and XmlTocursor you might choose ADO and pass an ADO recordset instead.
>>>>>>>>Another one is to pass a diffgram instead of all rows using CursorToXML and XMLToCursor.
>>>>>>>>Yet another one might be passing just an array of records that are updated/added/deleted with flags.
>>>>>>>>
>>>>>>>>Actually first I would think of "do I really want to talk between COM objects or even do I want a single COM object in my application" - sounds like I don't like COM objects:) Really I don't, too much problems with them for me (call it DLL hell, security etc etc).
>>>>>>>>
>>>>>>>>If one of them can connect to data why would other one cannot and a need for 2 evils?
>>>>>>>>Cetin
>>>>>>>>
>>>>>>>>>Thanks. This brings up another question.
>>>>>>>>>
>>>>>>>>>I want to use CURSORTOXML() and XMLTOCURSOR() to pass data to and
>>>>>>>>>from COM objects.
>>>>>>>>>
>>>>>>>>>Once I make changes to data and convert it to XML, and after I use
>>>>>>>>>XMLTOCURSOR() to create a cursor, whats the best way to update the
>>>>>>>>>database?
>>>>>>>>>
>>>>>>>>>I am using a VFP database now, with possible plans later to convert
>>>>>>>>>to SQL Server.
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>>>For the 'nOutputFormat', 'nFlags', 'cSchemaName', 'cSchemaLocation', and 'cNameSpace'
>>>>>>>>>>>parameters, are there any standards as far as what settings I should use?
>>>>>>>>>>>
>>>>>>>>>>>I am only using the command to pass data back & forth between COM objects.
>>>>>>>>>>
>>>>>>>>>>If there were standards there wouldn't be flags;)
>>>>>>>>>>nOutputFormat: 2 or 3 are my favorites. More compact.
>>>>>>>>>>nFlags: 1 to make it compact.
>>>>>>>>>>For others it depends. Probably "1" inline schema would be good.
>>>>>>>>>>
>>>>>>>>>>With these settings:
>>>>>>>>>>CursorToXml('myAlias','myMemvar',2,1,0,"1")
>>>>>>>>>>would create a compact XML with inline schema and store in m.myMemvar and IMHO is good for your need.
>>>>>>>>>>Cetin
