PyQGIS update/refresh composer legend [duplicate]

Question

I am trying to modify the data source of a raster layer in python, then update my composer and finally save it.

To modify my data source I found what is needed here: https://geogear.wordpress.com/2015/05/15/changing-qgis-layer-datasource-with-python/

The problem is that I lose the symbology of this layer in the legend of my composer. I tried different codes but none update my composer legend :

iface.activeComposers()[0].composition().refreshItems()

for i in iface.activeComposers()[0].composition().items():
    if isinstance(i,QgsComposerLegend):
        legend = i
        legend.updateLegend()

The only solution I found at the moment is to use the "setAutoUpdateModel" method on my legend and switch to True / False Auto Update to force the legend's update, but this solution is not optimal.

=> I wish I could just update the symbology for a particular layer in the legend of my compose (a bit like when in the interface of my composer I click on my legend then in "property of the object" right clicks on my layer and "back to default").

Would anyone have an idea to do that?

EDIT :

I have found a solution here : Changing legend item text with pyQGIS?

My new code :

for legendLyr in iface.mapCanvas().layers():
        renderer = legendLyr.renderer()
        myRenderer = renderer.clone()
        legendLyr.setRenderer(myRenderer)
        legendLyr.triggerRepaint()

Now my composer legend is refresh !