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Wiki source code of WOnder-ERXArrayUtilities

Last modified by Pascal Robert on 2012/02/11 08:27
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1 == Overview ==
2
3 ERXArrayUtilities provides convenience methods and tools for manipulating NSArrays. Many of the methods are self explanatory. For a full list please see the api ([[http:~~/~~/wocommunity.org/documents/javadoc/wonder/latester/extensions/foundation/ERXArrayUtilities.html>>url:http://wocommunity.org/documents/javadoc/wonder/latest/er/extensions/foundation/ERXArrayUtilities.html||shape="rect"]]).
4
5 === NSArray operators ===
6
7 WebObjects provides @sum, @avg, etc array operators. ERXArrayUtilities adds quite a few more:
8
9 **SortOperator:** Define an NSArray.Operator for the key //sort//.
10
11 This allows for key value paths like:
12
13 {{panel}}
14 myArray.valueForKey("@sort.firstName");
15 {{/panel}}
16
17 myArray.valueForKey("@sort.lastName,firstName");
18
19 Which in the first case would return myArray sorted ascending by first name and the second case
20 by lastName and then by firstName.
21
22 Other sort operators registered are: @sortAsc, @sortDesc, @sortInsensitiveAsc, @sortInsensitiveDesc
23
24 **FetchSpecOperator:** Define an NSArray.Operator for the key //fetchSpec//.
25
26 This allows for key value paths like:
27
28 {{panel}}
29 myArray.valueForKey("@fetchSpec.fetchUsers");
30 {{/panel}}
31
32 Which in this case would return myArray filtered and sorted by the
33 EOFetchSpecification named "fetchUsers" which must be a model-based fetchspec in the
34 first object's entity.
35
36 **FlattenOperator:** Define an NSArray.Operator for the key //flatten//.
37
38 This allows for key value paths like:
39
40 {{panel}}
41 myArray.valueForKey("@flatten");
42 {{/panel}}
43
44 Which in this case would return myArray flattened if myArray is an NSArray of NSArrays (of NSArrays etc).
45
46 **IsEmptyOperator:** Define an NSArray.Operator for the key //isEmpty//.
47
48 This allows for key value paths like:
49
50 {{panel}}
51 myArray.valueForKey("@isEmpty");
52 {{/panel}}
53
54 **SubarrayWithRangeOperator:** Define an NSArray.Operator for the key //subarrayWithRange//.
55
56 This allows for key value paths like:
57
58 {{panel}}
59 myArray.valueForKey("@subarrayWithRange.3-20");
60 {{/panel}}
61
62 **UniqueOperator:** Define an NSArray.Operator for the key //unique//.
63
64 This allows for key value paths like:
65
66 {{panel}}
67 myArray.valueForKeyPath("@unique.someOtherPath");
68 {{/panel}}
69
70 Which in this case would return only those objects which are unique in myArray.
71
72 **RemoveNullValuesOperator:** Define an NSArray.Operator for the key //removeNullValues//.
73
74 This allows for key value paths like:
75
76 {{panel}}
77 myArray.valueForKeyPath("@removeNullValues.someOtherPath");
78 {{/panel}}
79
80 Which in this case would return myArray without the occurrences of NSKeyValueCoding.Null.
81
82 **ObjectAtIndexOperator:** Define an NSArray.Operator for the key //objectAtIndex//.
83
84 This allows for key value paths like:
85
86 {{panel}}
87 myArray.valueForKey("@objectAtIndex.3.firstName");
88 {{/panel}}
89
90 **AvgNonNullOperator:** Define an NSArray.Operator for the key //avgNonNull//.
91
92 This allows for key value paths like:
93
94 {{panel}}
95 myArray.valueForKey("@avgNonNull.revenue");
96 {{/panel}}
97
98 which will sum up all values and divide by the number of nun-null entries.
99
100 **ReverseOperator:** Define an NSArray.Operator for the key //reverse//.
101
102 This allows for key value paths like:
103
104 {{panel}}
105 myArray.valueForKey("@reverse.someMorePath");
106 {{/panel}}
107
108 which return a reversed result as to you would normally get.
109
110 **MedianOperator:** Define an NSArray.Operator for the key //median//.
111
112 This allows for key value paths like:
113
114 {{panel}}
115 myArray.valueForKey("@median.someMorePath");
116 {{/panel}}
117
118 which return the median of the array elements at the given key path.
119 The median is the value for which half of the elements are above and half the elements are below.
120 As such, an array sort is needed and this might be very costly depending of the size of the array.