Add Layer Error

MaryM

I am setting up a file to format a map template.  I am stuck at the Add Layer section.  I have a dictionary which is layer name:layer path.  I want to grab all the layer paths and add them as layers to the map template.  How can I fix my code?

TemplateLayers=(r"\\...\TemplateLayers.txt")
lyrDict={}
with open (TemplateLayers) as f:
    for line in f:
        (key,val)=line.split(",")
        lyrDict[(key)]=val
f.close()

print lyrDict

#Step 2: Pull the layers into the MXD at the bottom of the data frame from the dictionary.
for val in lyrDict.values():
    arcpy.mapping.AddLayer("",(val),"Bottom") 

I get: Runtime error <type 'exceptions.AssertionError'>:
When I print my dictionary it looks like this:
{'Roads':'\\\\filepath\\filename.lyr',etc....}

ArkadiuszMatoszka

AddLayer takes 3 arguments:

AddLayer (data_frame, add_layer, {add_position})

where data_frame must be instance of arcpy.mapping.DataFrame, add_layer must be instance of arcpy.Layer.
All you have to do is define data frame of mxd and create arcpy.Layer()'s from paths so:

TemplateLayers=(r"\\...\TemplateLayers.txt")
lyrDict={}
with open (TemplateLayers) as f:
    for line in f:
        key,val=line.split(",")
        lyrDict[key]=val
f.close()

print lyrDict
mxd = arcpy.mapping.MapDocument('path\\to\\mxd.mxd')
df = arcpy.mapping.ListDataFrames(mxd)[0]
#Step 2: Pull the layers into the MXD at the bottom of the data frame from the dictionary.
for val in lyrDict.values():
    arcpy.mapping.AddLayer(df,arcpy.Layer(val),"Bottom")

That should do.
Regards
Arek