[GIS] Changing Data Source of Layer in QGIS

data-sourceqgis

Is there a way to source a shapefile to a layer file in QGIS much like how you do this in the properties of an ArcGIS layer? (i.e. Go to layer properties, source tab and then just depress the 'Set Dat Source' button)

I've been all over the layer properties in QGIS and I don't see this anywhere…

EDIT: I've received comments explaining that you cannot do this with shapefiles, but if I were to change the name of a shapefile and then open a pre-existing project file which contains this shapefile as a layer, I will get the 'Handle Bad Layers' dialogue, which allows me to navigate and re-source the layer to any shapefile I want to. I find it odd that you can resource in that scenario, but you cannot do it manually through the layer properties dialogue box.

Best Answer

This can now be done easily with a plugin:

changeDataSource

https://geogear.wordpress.com/2015/09/30/changedatasource-plugin-release-1-0/

It adds a button when you right click on a vector layer "Change vector datasource", so just as easy as Arc.

Related Solutions

QGIS Layer File – Equivalent of ArcGIS’s Layer (*.LYR) File

It does now :)

Only in the dev version but something like this could be added in an older release using a plugin. If I get some time I might just do that.

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A QGIS Layer Definition file will have the *.qlr extension and is a XML dump of the maplayer node for the project.

The start of the file will look like this:

<!DOCTYPE qgis-layer-definition>
<maplayer minimumScale="-4.65661e-10" maximumScale="1e+08" simplifyDrawingHints="1" minLabelScale="0" maxLabelScale="1e+08" simplifyDrawingTol="1" geometry="Polygon" simplifyMaxScale="1" type="vector" hasScaleBasedVisibilityFlag="0" simplifyLocal="1" scaleBasedLabelVisibilityFlag="0">
  <datasource>F:/gis_data/cadastre.shp</datasource>
  <title></title>
  <abstract></abstract>
  <keywordList>
    <value></value>
  </keywordList>
  <layername>cadastre</layername>
  ... {style, etc}
</maplayer

QGIS 2.8 Update

As of 2.8 QLR files now support many layers as well as groups. Right click on a group in the legend to save it out to a QLR file everything under the group will be saved to the QLR file.

QGIS Layers – How to Make QGIS Layer Update from Changed Data Source

This is related to the introduction of the OGR connection pool. [1]

Before QGIS 2.10, a file was reopened on every single access (e.g. repaint).

Since QGIS 2.10 the file handle is kept open and this means if a file is replaced the handle still points to the old file on Unix based systems.

QGIS 2.10: workaround

Unfortunately there is no API to nicely force QGIS to reopen the file in QGIS 2.10. As a workaround you can use an ugly hack:

layer.dataProvider().changeAttributeValues( { -1: { 0: 0 } } )
layer.triggerRepaint()

QGIS 2.12: solution

I just introduced a new method which will be available starting from QGIS 2.12:

layer.dataProvider().forceReload()
layer.triggerRepaint()

General approach

If you have the possibility to control how the file is being overwritten you can open the existing files with write permissions and change the content instead of replacing the files completely (delete/recreate) on disk.

[1] The connection pool was introduced to significantly speed up access to certain data sources.