Complete Exercise 6-29: CouchDB

Chap6/requirements.txt

@@ -1,3 +1,4 @@
 SQLAlchemy==1.1.14
 SQLObject==3.4.0
 mysql-connector==2.1.6
+couchdb

Chap6/ushuffle_couch.py

@@ -0,0 +1,89 @@
+#!/usr/bin/env python3
+
+from distutils.log import warn as printf
+from random import randrange as rand
+import couchdb
+from ushuffle_dbU import randName, FIELDS, tformat, cformat
+
+DBNAME = 'test_users'
+
+class CouchTest(object):
+    def __init__(self):
+        try:
+            self.couch = couchdb.Server()
+            del self.couch[DBNAME]
+        except couchdb.http.ResourceNotFound:
+            try:
+                self.users = self.couch.create(DBNAME)
+            except couchdb.http.ResourceNotFound:
+                raise RuntimeError()
+        else:
+            self.users = self.couch.create(DBNAME)
+
+
+    def insert(self):
+        for who, uid in randName():
+            self.users.save(
+            dict(login=who, userid=uid, projid=rand(1, 5))
+            )
+
+    def update(self):
+        fr = rand(1, 5)
+        to = rand(1, 5)
+        i = -1
+        for uid in self.users:
+            user = self.users[uid]
+            if user['projid'] == fr:
+                user['projid'] = to
+                self.users.save(user)
+                i += 1
+        return fr, to, i+1
+
+    def delete(self):
+        rm = rand(1, 5)
+        i = -1
+        for uid in self.users:
+            user = self.users[uid]
+            if user['projid'] == rm:
+                self.users.delete(user)
+                i += 1
+        return rm, i+1
+
+    def dbDump(self):
+        printf("\n%s" % "".join(map(cformat, FIELDS)))
+        for user in self.users:
+            printf("".join(map(tformat, (self.users[user][k] for k in FIELDS))))
+
+    def finish(self):
+        del self.couch  # Can't find a proper method to disconnect.
+
+
+def main():
+    printf("*** Connect to %r database" % DBNAME)
+    try:
+        couch = CouchTest()
+    except RuntimeError:
+        printf("\nERROR: MongoDB server unreachable, exit")
+        return
+
+    printf("\n*** Insert names into table")
+    couch.insert()
+    couch.dbDump()
+
+    printf("\n*** Move users to a random group")
+    fr, to, num = couch.update()
+    printf("\t(%d users moved) from (%d) to (%d)" % (num, fr, to))
+    couch.dbDump()
+
+    printf("\n*** Randomly delete group")
+    rm, num = couch.delete()
+    printf("\t(group #%d; %d users removed)" % (rm, num))
+    couch.dbDump()
+
+    printf("\n*** Drop users table")
+    del couch.couch[DBNAME]
+    printf("\n*** Close cxns")
+    couch.finish()
+
+if __name__ == "__main__":
+    main()

README.md

@@ -97,6 +97,7 @@
     * Exercise 6-26: Storm ORM - tried installing storm, in vain
     * Exercise 6-27: NoSQL ([for_nosql.md][6-27])
     * Exercise 6-28: NoSQL ([nosql_types.md][6-28])
+    * Exercise 6-29: CouchDB ([ushuffle_couch.py][6-29])
 
 [req2]: /requirements.txt
 [chap4]: /Chap4
@@ -173,4 +174,5 @@
 [6-23]: /Chap6/ushuffle_sad.py
 [6-24]: /Chap6/ushuffle_sae.py
 [6-27]: /Chap6/for_nosql.md
-[6-28]: /Chap6/nosql_types.md
+[6-28]: /Chap6/nosql_types.md
+[6-29]: /Chap6/ushuffle_couch.py