from json

generate_nodetree.py

import bpy
import json
import os
import ast

filename = 'node_tree.json'
location = 'C:\\blender_trunk'
fullpath = os.path.join(location, filename)

with open(fullpath) as fp:
    f = json.load(fp)

    nodegroup_params = {
        'name': 'NodeTest2',
        'type': 'SverchCustomTreeType'}

    ng = bpy.data.node_groups.new(**nodegroup_params)
    nodes = ng.nodes

    print('first import all.')
    for n in sorted(f):
        print('adding {0}'.format(n))
        bl_idname = f[n]['bl_idname']
        
        # add node and set name.
        # forget label for now.
        node = nodes.new(bl_idname)
        if not node.name == n:
            node.name = n

        node.location = f[n]['location']

        params = f[n]['params']
        for p in params:
            # val = ast.literal_eval(params[p])
            val = params[p]
            setattr(node, p, val)
        
    print('first import all.')
    for n in sorted(f):
        print(n)
        print('> ', f[n]['incoming'])
        print('> ', f[n]['outgoing'])