1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
|
'''
Created on Feb 19, 2011
@author: cgueret
'''
from rdflib import ConjunctiveGraph, RDF, URIRef, Namespace, Literal
import httplib
import urllib
import uuid
OLPC = Namespace("http://example.org/")
class DatastoreItem(object):
def __init__(self, type, id=None):
self.id = uuid.uuid1() if id is None else id
self.meta = {}
self.meta[RDF.type] = URIRef(OLPC[type])
def append_metadata(self, key, value):
'''
Append a new value for a given key
'''
# Set the namespace to the key
if type(key) == type(''):
key = OLPC[key]
# If not in, create
if key not in self.meta.keys():
self.meta[key] = []
else:
# Convert the key to an array if it was a singleton
if (type(self.meta[key]) != type([])):
tmp = self.meta[key]
self.meta[key] = [tmp]
# Append the value
self.meta[key].append(value)
def delete_metadata(self, key, value=None):
'''
Suppress a key or a value within a specific key
'''
# Set the namespace to the key
if type(key) == type(''):
key = OLPC[key]
if key not in self.meta.keys():
return
if value == None:
del self.meta[key]
else:
if (type(self.meta[key]) == type([])):
self.meta[key].remove(value)
if len(self.meta[key]) == 0:
del self.meta[key]
def set_metadata(self, key, value):
'''
Assign a specific value to a meta data key
'''
# If the key is a string, force the default namespace
if type(key) == type(''):
key = OLPC[key]
self.meta[key] = [value]
def get_metadata(self, key = None):
if key == None:
return self.meta.items()
else:
if type(key) == type(''):
key = OLPC[key]
if key not in self.meta.keys():
return []
return self.meta[key]
def get_resource(self):
return URIRef(OLPC['resource/%s' % self.id])
class Datastore(object):
def __init__(self, url):
self.url = url
def sparql_get(self, query):
params = {'query': query, 'format' : 'csv'}
headers = {'Content-Type': 'application/x-www-form-urlencoded'}
conn = httplib.HTTPConnection(self.url)
conn.request("POST", "/sparql",
urllib.urlencode(params), headers=headers)
response = conn.getresponse()
results = response.read().split('\n')[1:-1]
conn.close()
return results
def get_items(self, type):
'''
Query the datastore for all the items
'''
query = 'SELECT * WHERE { ?s <%s> <%s>} ORDER BY ?s'\
% (RDF.type, OLPC[type])
items = []
for line in self.sparql_get(query):
uri = line.split(',')[-1][4:-1]
id = uri.split('/')[-1]
print "load item %s" % id
item = DatastoreItem(type, id)
items.append(item)
# Load all the meta data
query = 'SELECT * WHERE { <%s> ?p ?o}' % item.get_resource()
for line in self.sparql_get(query):
(p,o) = line.split(',')[1:]
if p[4:-1] == 'http://www.w3.org/1999/02/22-rdf-syntax-ns#type':
continue
p = URIRef(p[4:-1])
if o[0:3] == 'uri':
o = URIRef(o[4:-1])
elif o[0] == '"':
o = Literal(o[1:-1])
item.set_metadata(p, o)
return items
def save_item(self, item):
'''
Convert the item into a graph and put the graph into the triple store
'''
# Delete the previous triples associated to that resource
# conn = httplib.HTTPConnection(self.url)
# conn.request("DELETE", "/data/%s" % item.get_resource())
# conn.close()
# Generate the new graph
graph = ConjunctiveGraph()
for (key, values) in item.get_metadata():
if type(values) == type([]):
for value in values:
graph.add((item.get_resource(), key, value))
else:
graph.add((item.get_resource(), key, values))
# Save it
#print graph.serialize()
headers = { 'Accept' : '*/*', 'Content-Type': 'application/rdf+xml' }
conn = httplib.HTTPConnection(self.url)
conn.request("PUT", "/data/%s" % item.get_resource(),
body=graph.serialize(), headers=headers)
conn.getresponse()
conn.close()
|
