--- /dev/null
+# $Id: Filter.py 14587 2009-07-19 13:18:50Z thierry $
+# $URL: svn+ssh://svn.planet-lab.org/svn/PLCAPI/trunk/PLC/Filter.py $
+from types import StringTypes
+try:
+ set
+except NameError:
+ from sets import Set
+ set = Set
+
+import time
+import pgdb
+
+from sfa.util.faults import *
+from sfa.util.parameter import Parameter, Mixed, python_type
+
+
+class Filter(Parameter, dict):
+ """
+ A type of parameter that represents a filter on one or more
+ columns of a database table.
+ Special features provide support for negation, upper and lower bounds,
+ as well as sorting and clipping.
+
+
+ fields should be a dictionary of field names and types
+ Only filters on non-sequence type fields are supported.
+ example : fields = {'node_id': Parameter(int, "Node identifier"),
+ 'hostname': Parameter(int, "Fully qualified hostname", max = 255),
+ ...}
+
+
+ filter should be a dictionary of field names and values
+ representing the criteria for filtering.
+ example : filter = { 'hostname' : '*.edu' , site_id : [34,54] }
+ Whether the filter represents an intersection (AND) or a union (OR)
+ of these criteria is determined by the join_with argument
+ provided to the sql method below
+
+ Special features:
+
+ * a field starting with the ~ character means negation.
+ example : filter = { '~peer_id' : None }
+
+ * a field starting with < [ ] or > means lower than or greater than
+ < > uses strict comparison
+ [ ] is for using <= or >= instead
+ example : filter = { ']event_id' : 2305 }
+ example : filter = { '>time' : 1178531418 }
+ in this example the integer value denotes a unix timestamp
+
+ * if a value is a sequence type, then it should represent
+ a list of possible values for that field
+ example : filter = { 'node_id' : [12,34,56] }
+
+ * a (string) value containing either a * or a % character is
+ treated as a (sql) pattern; * are replaced with % that is the
+ SQL wildcard character.
+ example : filter = { 'hostname' : '*.jp' }
+
+ * fields starting with - are special and relate to row selection, i.e. sorting and clipping
+ * '-SORT' : a field name, or an ordered list of field names that are used for sorting
+ these fields may start with + (default) or - for denoting increasing or decreasing order
+ example : filter = { '-SORT' : [ '+node_id', '-hostname' ] }
+ * '-OFFSET' : the number of first rows to be ommitted
+ * '-LIMIT' : the amount of rows to be returned
+ example : filter = { '-OFFSET' : 100, '-LIMIT':25}
+
+ A realistic example would read
+ GetNodes ( { 'node_type' : 'regular' , 'hostname' : '*.edu' , '-SORT' : 'hostname' , '-OFFSET' : 30 , '-LIMIT' : 25 } )
+ and that would return regular (usual) nodes matching '*.edu' in alphabetical order from 31th to 55th
+ """
+
+ def __init__(self, fields = {}, filter = {}, doc = "Attribute filter"):
+ # Store the filter in our dict instance
+ dict.__init__(self, filter)
+
+ # Declare ourselves as a type of parameter that can take
+ # either a value or a list of values for each of the specified
+ # fields.
+ self.fields = dict ( [ ( field, Mixed (expected, [expected]))
+ for (field,expected) in fields.iteritems()
+ if python_type(expected) not in (list, tuple, set) ] )
+
+ # Null filter means no filter
+ Parameter.__init__(self, self.fields, doc = doc, nullok = True)
+
+ def quote(self, value):
+ """
+ Returns quoted version of the specified value.
+ """
+
+ # The pgdb._quote function is good enough for general SQL
+ # quoting, except for array types.
+ if isinstance(value, (list, tuple, set)):
+ return "ARRAY[%s]" % ", ".join(map, self.quote, value)
+ else:
+ return pgdb._quote(value)
+
+ def sql(self, join_with = "AND"):
+ """
+ Returns a SQL conditional that represents this filter.
+ """
+
+ # So that we always return something
+ if join_with == "AND":
+ conditionals = ["True"]
+ elif join_with == "OR":
+ conditionals = ["False"]
+ else:
+ assert join_with in ("AND", "OR")
+
+ # init
+ sorts = []
+ clips = []
+
+ for field, value in self.iteritems():
+ # handle negation, numeric comparisons
+ # simple, 1-depth only mechanism
+
+ modifiers={'~' : False,
+ '<' : False, '>' : False,
+ '[' : False, ']' : False,
+ '-' : False,
+ }
+
+ for char in modifiers.keys():
+ if field[0] == char:
+ modifiers[char]=True;
+ field = field[1:]
+ break
+
+ # filter on fields
+ if not modifiers['-']:
+ if field not in self.fields:
+ raise GeniInvalidArgument, "Invalid filter field '%s'" % field
+
+ if isinstance(value, (list, tuple, set)):
+ # handling filters like '~slice_id':[]
+ # this should return true, as it's the opposite of 'slice_id':[] which is false
+ # prior to this fix, 'slice_id':[] would have returned ``slice_id IN (NULL) '' which is unknown
+ # so it worked by coincidence, but the negation '~slice_ids':[] would return false too
+ if not value:
+ field=""
+ operator=""
+ value = "FALSE"
+ else:
+ operator = "IN"
+ value = map(str, map(self.quote, value))
+ value = "(%s)" % ", ".join(value)
+ else:
+ if value is None:
+ operator = "IS"
+ value = "NULL"
+ elif isinstance(value, StringTypes) and \
+ (value.find("*") > -1 or value.find("%") > -1):
+ operator = "LIKE"
+ # insert *** in pattern instead of either * or %
+ # we dont use % as requests are likely to %-expansion later on
+ # actual replacement to % done in PostgreSQL.py
+ value = value.replace ('*','***')
+ value = value.replace ('%','***')
+ value = str(self.quote(value))
+ else:
+ operator = "="
+ if modifiers['<']:
+ operator='<'
+ if modifiers['>']:
+ operator='>'
+ if modifiers['[']:
+ operator='<='
+ if modifiers[']']:
+ operator='>='
+ else:
+ value = str(self.quote(value))
+
+ clause = "%s %s %s" % (field, operator, value)
+
+ if modifiers['~']:
+ clause = " ( NOT %s ) " % (clause)
+
+ conditionals.append(clause)
+ # sorting and clipping
+ else:
+ if field not in ('SORT','OFFSET','LIMIT'):
+ raise GeniInvalidArgument, "Invalid filter, unknown sort and clip field %r"%field
+ # sorting
+ if field == 'SORT':
+ if not isinstance(value,(list,tuple,set)):
+ value=[value]
+ for field in value:
+ order = 'ASC'
+ if field[0] == '+':
+ field = field[1:]
+ elif field[0] == '-':
+ field = field[1:]
+ order = 'DESC'
+ if field not in self.fields:
+ raise GeniInvalidArgument, "Invalid field %r in SORT filter"%field
+ sorts.append("%s %s"%(field,order))
+ # clipping
+ elif field == 'OFFSET':
+ clips.append("OFFSET %d"%value)
+ # clipping continued
+ elif field == 'LIMIT' :
+ clips.append("LIMIT %d"%value)
+
+ where_part = (" %s " % join_with).join(conditionals)
+ clip_part = ""
+ if sorts:
+ clip_part += " ORDER BY " + ",".join(sorts)
+ if clips:
+ clip_part += " " + " ".join(clips)
+# print 'where_part=',where_part,'clip_part',clip_part
+ return (where_part,clip_part)
git://git.onelab.eu / sfa.git / commitdiff