X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=trunk%2FPLC%2FFilter.py;fp=trunk%2FPLC%2FFilter.py;h=406349606cdf8eaa4516377bd2d0224c41837220;hb=5a4c1b1278ffa01e630fde47f7c54888ed20a576;hp=0000000000000000000000000000000000000000;hpb=cee5ab52df1c9f38b6eaff2dd354cb22f59028c7;p=plcapi.git diff --git a/trunk/PLC/Filter.py b/trunk/PLC/Filter.py new file mode 100644 index 0000000..4063496 --- /dev/null +++ b/trunk/PLC/Filter.py @@ -0,0 +1,203 @@ +from types import StringTypes +try: + set +except NameError: + from sets import Set + set = Set + +import time + +from PLC.Faults import * +from PLC.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, '-PAGE':25} + + A realistic example would read + GetNodes ( { 'hostname' : '*.edu' , '-SORT' : 'hostname' , '-OFFSET' : 30 , '-PAGE' : 25 } ) + and that would return 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 = {} + + for field, expected in fields.iteritems(): + # Cannot filter on sequences + if python_type(expected) in (list, tuple, set): + continue + + # Accept either a value or a list of values of the specified type + self.fields[field] = Mixed(expected, [expected]) + + # Null filter means no filter + Parameter.__init__(self, self.fields, doc = doc, nullok = True) + + # this code is not used anymore + # at some point the select in the DB for event objects was done on + # the events table directly, that is stored as a timestamp, thus comparisons + # needed to be done based on SQL timestamps as well + def unix2timestamp (self,unix): + s = time.gmtime(unix) + return "TIMESTAMP'%04d-%02d-%02d %02d:%02d:%02d'" % (s.tm_year,s.tm_mon,s.tm_mday, + s.tm_hour,s.tm_min,s.tm_sec) + + def sql(self, api, 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 PLCInvalidArgument, "Invalid filter field '%s'" % field + + if isinstance(value, (list, tuple, set)): + # Turn empty list into (NULL) instead of invalid () + if not value: + value = [None] + + operator = "IN" + value = map(str, map(api.db.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" + value = str(api.db.quote(value.replace("*", "%"))) + else: + operator = "=" + if modifiers['<']: + operator='<' + if modifiers['>']: + operator='>' + if modifiers['[']: + operator='<=' + if modifiers[']']: + operator='>=' + else: + value = str(api.db.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 PLCInvalidArgument, "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 PLCInvalidArgument, "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)