Vjylku

I have a model which adds and calculates a new field with a workspace path.
I upload only one layer from database to the model (called "tline"). Parse path can detect only the name and file of this layer, not the whole path to the GDB file which contains this layer. The path can be found only if I add a workspace variable and set the path to database in this variable. So when I set a parameter "Parse type" like "Path" for "tline" layer, model won't work, it just add a new field and says that "The process did not execute because the precondition is false."

How can I find the path to GDB automatically using model builder? It is also important when I have several GDB files that have the same layer "tline" within. I just want to overcome a manual input of GDB file into the model.

After seeing your conservation with @GISGE, though reluctantly, I have decided to put in my two cents. I do not think there is a direct way of getting file path of a layer's data source from given Model Builder tools. However you can use Calculate Value tool to get the required parts. Assuming you are always going to use LAYERs from your MXD's TOC, the setup below should work.

The difference here, Parse Path is not connected to your input layer and output_value is a precondition to Add Field to make sure Calculate Value will run before anything. The trick is to input the code very below into this tool as shown below.

And here is the code:

Expression

GetPath("%tline%")

Code Block

def GetPath(lyr):
import os
mxd=arcpy.mapping.MapDocument("CURRENT")
target=arcpy.mapping.ListLayers(mxd,lyr)[0]
return target.dataSource

ASSUMPTIONS

• this works only with LAYERs from your CURRENT (the map document which is already open and where your model is open in editing mode) MXD's TOC


• if there are more than two layers with the same name, this will get
  the first instance in the order of display


• it will only work with layers which support dataSource property (essentially the feature and raster layers are just safe)

First make sure you drag-and-drop the input feature class into your model from the Catalog Window or ArcCatalog, and not as a layer from ArcMap's TOC. Otherwise the path property (and extension) can't be retrieved.

Then use the expression '%Value%' with the PYTHON parser in the Calculate Field:

Make sure your new field is long enough to hold the dataset's path (the default 50 characters might not be enough).

And reading this comment "First make sure you drag-and-drop the input feature class into your model from the Catalog Window or ArcCatalog, and not as a layer from ArcMap's TOC. Otherwise the path property (and extension) can't be retrieved." made my day and solved a problem puzling me for the last two days - why a new tool I created to add Path field and populate would not populate the path values. A Modelbuilder 'gotcha' that I have not seen explained anywhere else. Many thanks!