FieldMap in Arcpy Merge for Selected Fields Only

Question

I am trying to use FieldMap in arcpy to merge only a few of the same fields from 8 feature classes. There are many different fields in all of the different feature classes, but I have identified the 9 fields I want in my final merged feature class. Instead of merging all the fields I identify it only chooses the first field in my list and I end up with a merged file with one field "COUNTY_F". What am I missing?

fClasses = []
i=0

#Loop through MyGDB.gdb and add each feature class name to array
fcs = arcpy.ListFeatureClasses()

for fc in fcs:   
    fClasses.append(fc)
    i = i+1

print fClasses
#Shows as "Clallam_WorkingForest_2013, GraysHarbor_WorkingForest_2013, Jefferson_WorkingForest_2013, King_WorkingForest_2013, Kittitas_WorkingForest_2013, Mason_WorkingForest_2013, Pierce_WorkingForest_2013, Snohomish_WorkingForest_2013"

#Map Fields for Merge
inFields= ["COUNTY_F", "UNIQUE_ID", "TAXPAYER", "PARCEL_ID", "CURRENTUSE_CODE", "CURRENTUSE_DESC", "PRESENTUSE_CODE", "PRESENTUSE_DESC", "ACRES_ASSES"]

fm = arcpy.FieldMappings()
fm_type = arcpy.FieldMap()

for field in inFields:
    fm_type.addInputField( "Clallam_WorkingForest_2013", field.name)
    fm_type.addInputField( "GraysHarbor_WorkingForest_2013", field.name)
    fm_type.addInputField( "Jefferson_WorkingForest_2013", field)
    fm_type.addInputField( "King_WorkingForest_2013", field)
    fm_type.addInputField( "Kittitas_WorkingForest_2013", field)
    fm_type.addInputField( "Mason_WorkingForest_2013", field)
    fm_type.addInputField( "Pierce_WorkingForest_2013", field)
    fm_type.addInputField( "Snohomish_WorkingForest_2013", field)

fm.addFieldMap(fm_type)
print "Fields mapped!"

arcpy.Merge_management(fClasses, "Merged", fm)
print "Merge: SUCCESS."

Answer 1

Is probably your understanding about FieldMap is wrong. Because one field relation with one FieldMap object,so you need create nine FieldMap object in your case.In addition,inFields is a list,you can not use field.name.

Modify the code as follows,I think that the result you want to obtain.

import arcpy
fClasses = []
i=0

#Loop through MyGDB.gdb and add each feature class name to array
fcs = arcpy.ListFeatureClasses()

for fc in fcs:
    fClasses.append(fc)
    i = i+1

print fClasses
#Shows as "Clallam_WorkingForest_2013, GraysHarbor_WorkingForest_2013, Jefferson_WorkingForest_2013, King_WorkingForest_2013, Kittitas_WorkingForest_2013, Mason_WorkingForest_2013, Pierce_WorkingForest_2013, Snohomish_WorkingForest_2013"

#Map Fields for Merge
inFields= ["COUNTY_F", "UNIQUE_ID", "TAXPAYER", "PARCEL_ID", "CURRENTUSE_CODE", "CURRENTUSE_DESC", "PRESENTUSE_CODE", "PRESENTUSE_DESC", "ACRES_ASSES"]

fm = arcpy.FieldMappings()
fm_types =[]
for i in range(9):
    fm_types.append(arcpy.FieldMap())

for fm_type in fm_types:
    for fClass in fClasses:
        for filed in inFields:
            fm_type.addInputField(fClass,field)
            outField=fm_type.outputField
            outField.name=field
            fm_type.outputField=outField
            #Sequentially add nine FieldObject
            fm.addFieldMap(fm_type)

print "Fields mapped!"

arcpy.Merge_management(fClasses, "Merged", fm)
print "Merge: SUCCESS."

I am sorry,I was wrong to write loop.

import arcpy
fClasses = []
i=0

#Loop through MyGDB.gdb and add each feature class name to array
fcs = arcpy.ListFeatureClasses()

for fc in fcs:
    fClasses.append(fc)
    i = i+1

print fClasses
#Shows as "Clallam_WorkingForest_2013, GraysHarbor_WorkingForest_2013, Jefferson_WorkingForest_2013, King_WorkingForest_2013, Kittitas_WorkingForest_2013, Mason_WorkingForest_2013, Pierce_WorkingForest_2013, Snohomish_WorkingForest_2013"

#Map Fields for Merge
inFields= ["COUNTY_F", "UNIQUE_ID", "TAXPAYER", "PARCEL_ID", "CURRENTUSE_CODE", "CURRENTUSE_DESC", "PRESENTUSE_CODE", "PRESENTUSE_DESC", "ACRES_ASSES"]

fm = arcpy.FieldMappings()
for i in range(9):
    fm_type=arcpy.FieldMap()
    for fClass in fClasses:
        fm_type.addInputField(fClass,inFields[i])
        outField=fm_type.outputField
        outField.name=inFields[i]
        fm_type.outputField=outField
    #Sequentially add nine FieldObject
    fm.addFieldMap(fm_type)

print "Fields mapped!"

arcpy.Merge_management(fClasses, "Merged", fm)
print "Merge: SUCCESS."