from types import StringTypes try: set except NameError: from sets import Set set = Set import time try: import pgdb except: pass 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 valid_fields = {} for field in filter: if field in fields: valid_fields[field] = filter[field] dict.__init__(self, valid_fields) # 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 SfaInvalidArgument, "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 SfaInvalidArgument, "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 SfaInvalidArgument, "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) return (where_part,clip_part)