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I have a script that was working, where I was able to grab a composer label by its ID and then update its text by doing the following:

labelTitle = myComposition.getComposerItemById('pageTitle')
labelTitle.setText('New Title')

But after updating to the latest version of QGIS, it looks like labelTitle is coming back as a QgsComposerItem type instead of QgsComposerLabel, so it is throwing the error 'QgsComposerItem' object has no attribute 'setText'

Is there a way to cast it as a label, or am I missing something? Or is there an entirely better way to accomplish this?

4
  • Do you generate your title from a field in the map or are you using the atlas function?. If using a field in a vector file you could do something like This is the [%"field_name"%] where field name would hold your string
    – LaughU
    Commented May 22, 2017 at 6:01
  • @LaughU Yeah I actually just figured this out and was about to update my post. I'm generating it from a field and was doing it programmatically in the script so that I could change the size based on the length of the title, but I ended up just using a conditional in the label expression. I'm still curious how to target a composer label with Python though!
    – Alex
    Commented May 22, 2017 at 6:17
  • could you add which QGIS version you used and which you are using now?
    – LaughU
    Commented May 22, 2017 at 12:28
  • @LaughU I'm on 2.18.7 running on a Mac, previously I want to say it was 2.18.0
    – Alex
    Commented May 22, 2017 at 16:29

3 Answers 3

2

Another workaround suggested by Nyall Dawson (cast) :

from qgis.core import QgsProject, QgsLayoutItemPicture
import sip
myLayout = QgsProject.instance().layoutManager().layoutByName('test')
myLayoutPicture = sip.cast(myLayout.itemById("picture"), QgsLayoutItemPicture)
myLayoutPicture.setPicturePath("path to an image")
0

same problem for me, solved with this:

    [...]
    item = myComposition.getComposerItemById("id_field")
    item = self.bugWAGetComposerLabel(item)
    item.setText("my value")
    [...]


def bugWAGetComposerLabel(self, item):
    if not item.__class__ == QgsComposerLabel:
        if item.type() == QgsComposerItem.ComposerLabel:
            item.__class__ = QgsComposerLabel
    return item
1
  • Same problem here (QGIS 2.99), but with this code I get an error : 'QgsComposerLabel' object has no attribute 'setText'
    – sigeal
    Commented Nov 28, 2017 at 9:48
0

Here is the workaround I found with the help of QGIS Developer list :

@staticmethod
def getCompositionItem(composition, itemId, itemClass):
    item = None
    for item in composition.items():
        if isinstance(item, itemClass):
            if item.id() == itemId:
                return item

Using this custom function instead of getComposerItemById I can get composition items with their actual subclass.

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