Implement double-precision Number

.. as an option to the 'Number' property.

Author: schlatterbeck

CHANGES.txt

@@ -145,7 +145,10 @@ Features:
 - When storing user-defined queries we now store the template with the
   query if the template name is different from 'index'. This allows
   stored queries for templates different from the default 'index'
-  template.
+  template. (Ralf Schlatterbeck)
+- Number properties now have an optional attribute use_double to request
+  double precision float as the storage type for this property. (Ralf
+  Schlatterbeck)
 
 Fixed:
 
@@ -329,15 +332,16 @@ Fixed:
   exceptions. This occured for example if editing an issue with the
   classic template and setting 'superseder' to a non-existing issue
   number. All changes to the form where the original field was non-empty
-  were lost.
+  were lost. (Ralf Schlatterbeck)
 - Fix submit_once Javascript function: This needs to return a boolean
   value (not and integer like 0 or 1). And the work-around for an
   ancient version of Internet Explorer would make it break for a recent
   Firefox. The old version would show the popup but after clicking away
   the alert it would load the page. The new version (tested with
-  Chromium and Firefox) doesn't load the page.
+  Chromium and Firefox) doesn't load the page. (Ralf Schlatterbeck)
 - Fix Traceback in backends/portalocker.py on windows due to missing
   windll import, thanks to Heiko Stegmann for suggesting a first fix.
+  (Ralf Schlatterbeck)
 
 
 2016-01-11: 1.5.1

doc/customizing.txt

@@ -656,7 +656,8 @@ A Class is comprised of one or more properties of the following types:
 * Date properties store date-and-time stamps. Their values are Timestamp
   objects.
 * Integer properties store integer values. (Number can store real/float values.)
-* Number properties store numeric values.
+* Number properties store numeric values. There is an option to use
+  double-precision floating point numbers.
 * Boolean properties store on/off, yes/no, true/false values.
 * A Link property refers to a single other item selected from a
   specified class. The class is part of the property; the value is an
@@ -671,6 +672,8 @@ behaviour:
   property should be part of the full text index. The default is 'no' but this
   can be set to 'yes' to allow a property's contents to be in the full
   text index.
+* Number properties can have a ``use_double`` attribute that, when set
+  to ``True``, will use double precision floating point in the database.
 * Link and Multilink properties can have several attributes:
 
   - ``do_journal``: By default, every change of a link property is

roundup/backends/back_sqlite.py

@@ -54,6 +54,13 @@ class Database(rdbms_common.Database):
     # used by some code to switch styles of query
     implements_intersect = 1
 
+    # used in generic backend to determine if db supports
+    # 'DOUBLE PRECISION' for floating point numbers. Note that sqlite
+    # already has double precision as its standard 'REAL' type. So this
+    # is set to False here.
+
+    implements_double_precision = False
+
     hyperdb_to_sql_datatypes = {
         hyperdb.String : 'VARCHAR(255)',
         hyperdb.Date   : 'VARCHAR(30)',

roundup/backends/rdbms_common.py

@@ -453,6 +453,10 @@ def reindex(self, classname=None, show_progress=False):
                     klass.index(nodeid)
         self.indexer.save_index()
 
+    # Used here in the generic backend to determine if the database
+    # supports 'DOUBLE PRECISION' for floating point numbers.
+    implements_double_precision = True
+
     hyperdb_to_sql_datatypes = {
         hyperdb.String : 'TEXT',
         hyperdb.Date   : 'TIMESTAMP',
@@ -464,9 +468,12 @@ def reindex(self, classname=None, show_progress=False):
         hyperdb.Integer   : 'INTEGER',
     }
 
-    def hyperdb_to_sql_datatype(self, propclass):
+    def hyperdb_to_sql_datatype(self, propclass, prop = None):
 
         datatype = self.hyperdb_to_sql_datatypes.get(propclass)
+        if self.implements_double_precision and prop and \
+          isinstance(prop, Number) and prop.use_double:
+            datatype = 'DOUBLE PRECISION'
         if datatype:
             return datatype
 
@@ -500,7 +507,7 @@ def determine_columns(self, properties):
                 #and prop.find('Multilink') != -1:
                 #mls.append(col)
 
-            datatype = self.hyperdb_to_sql_datatype(prop.__class__)
+            datatype = self.hyperdb_to_sql_datatype(prop.__class__, prop)
             cols.append(('_'+col, datatype))
 
             # Intervals stored as two columns
@@ -579,7 +586,7 @@ def update_class(self, spec, old_spec, force=0):
                 self.create_multilink_table(spec, propname)
             else:
                 # add the column
-                coltype = self.hyperdb_to_sql_datatype(prop.__class__)
+                coltype = self.hyperdb_to_sql_datatype(prop.__class__, prop)
                 sql = 'alter table _%s add column _%s %s'%(
                     spec.classname, propname, coltype)
                 self.sql(sql)

roundup/hyperdb.py

@@ -293,6 +293,17 @@ def from_raw(self, value, **kw):
 
 class Number(_Type):
     """An object designating a numeric property"""
+    def __init__(self, use_double = False, **kw):
+        """ The value use_double tells the database backend to use a
+            floating-point format with more precision than the default.
+            Usually implemented by type 'double precision' in the sql
+            backend. The default is to use single-precision float (aka
+            'real') in the db. Note that sqlite already uses 8-byte for
+            floating point numbers.
+        """
+        self.use_double = use_double
+        _Type.__init__ (self, **kw)
+        super(Number, self).__init__(**kw)
     def from_raw(self, value, **kw):
         value = value.strip()
         try:

test/db_test_base.py

@@ -80,9 +80,11 @@ def setupSchema(db, create, module):
     status.setkey("name")
     priority = module.Class(db, "priority", name=String(), order=String())
     priority.setkey("name")
-    user = module.Class(db, "user", username=String(), password=Password(quiet=True),
-                        assignable=Boolean(quiet=True), age=Number(quiet=True), roles=String(), address=String(),
-                        rating=Integer(quiet=True), supervisor=Link('user'),realname=String(quiet=True))
+    user = module.Class(db, "user", username=String(),
+        password=Password(quiet=True), assignable=Boolean(quiet=True),
+        age=Number(quiet=True), roles=String(), address=String(),
+        rating=Integer(quiet=True), supervisor=Link('user'),
+        realname=String(quiet=True), longnumber=Number(use_double=True))
     user.setkey("username")
     file = module.FileClass(db, "file", name=String(), type=String(),
         comment=String(indexme="yes"), fooz=Password())
@@ -92,18 +94,16 @@ def setupSchema(db, create, module):
     mynosy = Multilink("user")
     mynosy.quiet = True
     issue = module.IssueClass(db, "issue", title=String(indexme="yes"),
-                              status=Link("status"), nosy=mynosy, deadline=Date(quiet=True),
-                              foo=Interval(quiet=True, default_value=date.Interval('-1w')), files=Multilink("file"), assignedto=Link('user', quiet=True),
-        priority=Link('priority'), spam=Multilink('msg'),
-        feedback=Link('msg'))
+        status=Link("status"), nosy=mynosy, deadline=Date(quiet=True),
+        foo=Interval(quiet=True, default_value=date.Interval('-1w')),
+        files=Multilink("file"), assignedto=Link('user', quiet=True),
+        priority=Link('priority'), spam=Multilink('msg'), feedback=Link('msg'))
     stuff = module.Class(db, "stuff", stuff=String())
     session = module.Class(db, 'session', title=String())
     msg = module.FileClass(db, "msg", date=Date(),
-                           author=Link("user", do_journal='no'),
-                           files=Multilink('file'), inreplyto=String(),
-                           messageid=String(),
-                           recipients=Multilink("user", do_journal='no')
-                           )
+        author=Link("user", do_journal='no'), files=Multilink('file'),
+        inreplyto=String(), messageid=String(),
+        recipients=Multilink("user", do_journal='no'))
     session.disableJournalling()
     db.post_init()
     if create:
@@ -538,6 +538,34 @@ def testNumberUnset(self):
         self.db.user.set(nid, age=None)
         self.assertEqual(self.db.user.get(nid, "age"), None)
 
+    # Long number
+    def testDoubleChange(self):
+        lnl = 100.12345678
+        ln  = 100.123456789
+        lng = 100.12345679
+        nid = self.db.user.create(username='foo', longnumber=ln)
+        self.assertEqual(self.db.user.get(nid, 'longnumber') < lng, True)
+        self.assertEqual(self.db.user.get(nid, 'longnumber') > lnl, True)
+        lnl = 1.0012345678e55
+        ln  = 1.00123456789e55
+        lng = 1.0012345679e55
+        self.db.user.set(nid, longnumber=ln)
+        self.assertEqual(self.db.user.get(nid, 'longnumber') < lng, True)
+        self.assertEqual(self.db.user.get(nid, 'longnumber') > lnl, True)
+        self.db.user.set(nid, longnumber=-1)
+        self.assertEqual(self.db.user.get(nid, 'longnumber'), -1)
+        self.db.user.set(nid, longnumber=0)
+        self.assertEqual(self.db.user.get(nid, 'longnumber'), 0)
+
+        nid = self.db.user.create(username='bar', longnumber=0)
+        self.assertEqual(self.db.user.get(nid, 'longnumber'), 0)
+
+    def testDoubleUnset(self):
+        nid = self.db.user.create(username='foo', longnumber=1.2345)
+        self.db.user.set(nid, longnumber=None)
+        self.assertEqual(self.db.user.get(nid, "longnumber"), None)
+
+
     # Integer
     def testIntegerChange(self):
         nid = self.db.user.create(username='foo', rating=100)