How do I load multiple shapefiles into the same existing feature class?

Question

I have a hundreds of shapefiles and, based on the filename, I need to load it into one of three feature classes (points, polylines, or polygons). My code works until it tries to load the second file of a particular type. Then, I get an error "FC_NAME already exists". Yes, it already exists, that's exactly what I want. Now load the shapefile into the feature class, please!

How do I load a shapefile into an existing feature class?

Here's the code, trimmed down to exclude logic that gets to this point:

result = arcpy.FeatureClassToFeatureClass_conversion(shp, outputLocation, outputPointsFC)

Answer 1

Here's a script I just happened to have lying around, it merges all lines, points and polygons from a database into a new database feature class; there's no field mapping, at this time we just wanted to see all the geometries together without having to load over 1k layers...

A feature class (shapefile or database) can only store one geometry type so it's important to test that before deciding where to put it.

import arcpy, os, sys

# set your parameters input and output database
InDB = sys.argv[1]
OutDB = sys.argv[2]

if not os.path.exists(OutDB):
    DBpath = os.path.dirname(OutDB)
    DBname = os.path.basename(OutDB)
    name,ext = os.path.splitext(DBname)
    if ext.upper() == ".MDB":
        arcpy.AddMessage("Creating output personal database")
        arcpy.CreatePersonalGDB_management(DBpath,DBname)
    elif ext.upper() == ".GDB":
        arcpy.AddMessage("Creating output file database")
        arcpy.CreateFileGDB_management(DBpath,DBname)
    else:
        arcpy.AddError("Unknown output database format")

# set your workspace for ListDatasets
arcpy.env.workspace = InDB

# create empty lists
LineList = list()
PointList = list()
PolyList = list()

# Standalone feature classes
for FeatClass in arcpy.ListFeatureClasses():
    desc = arcpy.Describe(InDB + "\\" + FC + "\\" + FeatClass)
    if desc.shapeType == "Point":
        PointList.append(InDB + "\\" + FC + "\\" + FeatClass)
    elif desc.shapeType == "Polyline":
        LineList.append(InDB + "\\" + FC + "\\" + FeatClass)
    elif desc.shapeType == "Polygon":
        PolyList.append(InDB + "\\" + FC + "\\" + FeatClass)

# iterate through feature datasets
for FC in arcpy.ListDatasets():
    arcpy.env.workspace = InDB + "\\" + FC
    for FeatClass in arcpy.ListFeatureClasses():
        desc = arcpy.Describe(InDB + "\\" + FC + "\\" + FeatClass)
        if desc.shapeType == "Point":
            PointList.append(InDB + "\\" + FC + "\\" + FeatClass)
        elif desc.shapeType == "Polyline":
            LineList.append(InDB + "\\" + FC + "\\" + FeatClass)
        elif desc.shapeType == "Polygon":
            PolyList.append(InDB + "\\" + FC + "\\" + FeatClass)

arcpy.AddMessage("Performing merge")
if len(PointList) > 0:
    arcpy.Merge_management(PointList,OutDB + "\\Merged_Points")
if len(LineList) > 0:
    arcpy.Merge_management(LineList,OutDB + "\\Merged_Lines")
if len(PolyList) > 0:
    arcpy.Merge_management(PolyList,OutDB + "\\Merged_Polygons")

If you replace arcpy.Merge_management (smash a bunch together to a new feature class) with arcpy.Append_management (insert a bunch of feature classes into an existing feature class) then it should do pretty much what you're after - if you do you will also need to change the output to the full path to the existing datasets to insert into.