Hi Matthias

I follow the steps in the link you posted and get the following errors when
trying to import

ImportError: cannot import name QgsEditException

Do I have to install some modules? Didn't find any luck on google.

Best regards,
Zhang Qun

On Wed, Jun 13, 2018 at 6:16 PM, Matthias Kuhn <matth...@opengis.ch> wrote:

> Glad you like it :)
>
> Forwading this answer also to the mailing list for future reference,
> Ethan, you need to use "reply to all" in your mail application or other
> are not able to follow our conversation (which would be a pity ;) ).
>
> Best regards
> Matthias
>
> On 06/13/2018 12:13 PM, Zhang Qun wrote:
> > Wow, i was about to look into the with() statement. It looks much
> > better.  Many thanks for the link.
> >
> > Regards,
> > Ethan
> >
> >
> > On Wed, Jun 13, 2018, 6:03 PM Matthias Kuhn <matth...@opengis.ch
> > <mailto:matth...@opengis.ch>> wrote:
> >
> >     Hi Ethan,
> >
> >     there are of course advantages and disadvantages of both methods,
> but in
> >     most cases the QgsVectorLayer ones just "do the right thing",
> especially
> >     when used with a `with` block, see also this post:
> >
> >     http://www.opengis.ch/2015/08/12/with-edit-layer/
> >
> >     Cheers
> >     Matthias
> >
> >     On 06/13/2018 11:59 AM, Zhang Qun wrote:
> >     > Hi Matthias,
> >     >
> >     > Thanks very much for the instruction. I will try it out. The
> >     > dataProvider method seems simpler to me and it can set attributes
> in
> >     > batch as it takes a list as input. The layer method seems only
> >     takes one
> >     > input. If i want to change 10 attributes of a feature, i have to
> issue
> >     > 10 commands.
> >     >
> >     > Best regards,
> >     > Ethan
> >     >
> >     >
> >     > On Wed, Jun 13, 2018, 5:45 PM Matthias Kuhn <matth...@opengis.ch
> >     <mailto:matth...@opengis.ch>
> >     > <mailto:matth...@opengis.ch <mailto:matth...@opengis.ch>>> wrote:
> >     >
> >     >     Hi Ethan
> >     >
> >     >     On 06/13/2018 11:18 AM, Zhang Qun wrote:
> >     >     > Hi everyone, i"m using QGIS2.18, and trying to change feature
> >     >     attributes
> >     >     > using the following two methods:
> >     >     >
> >     >     > *dataProvider:*
> >     >     >
> >     >     > |attrs
> >     >     ={0:"hello",1:123}layer.dataProvider().
> changeAttributeValues({fid
> >     >     > :attrs })|
> >     >     >
> >     >     > *layer object:*
> >     >     >
> >     >     >
> >     >
> >      |layer.startEditing()layer.changeAttributeValue(fid,
> fieldIndex,value)layer.commitChanges()|
> >     >     >
> >     >     > I keep the attribute table open, and monitor the changes.
> >     The first
> >     >     > method dataProvider is not able to update the attribute
> >     table on the
> >     >     > fly, even the "reload table" button on the top menu of the
> >     table does
> >     >     > not work. I have to re-open the table to see the changes.
> >     The second
> >     >     > method is working, the attribute table gets instantly
> updated.
> >     >     >
> >     >     > I would like to stay with the dataProvider method but not
> >     sure how to
> >     >     > get instantly updated attribute table?
> >     >
> >     >     The provider's dataChanged() signal needs to be emitted, I
> >     think you can
> >     >     directly emit that or call `dataProvider().forceReload()`.
> >     >
> >     >     Out of curiosity, why would you like to stay with the
> >     dataProvider
> >     >     method?
> >     >
> >     >     Bests
> >     >     Matthias
> >     >
> >     >
> >     >     >
> >     >     > Thanks.
> >     >     >
> >     >     > Best regards,
> >     >     > Ethan
> >     >     >
> >     >     >
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