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Version 5.1 by smmccraw on 2007/07/08 09:46
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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:~/~/webobjects.mdimension.com/wonder/api/er/extensions/ERXArrayUtilities.html).
4
5 === NSArray operators ===
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7 WebObjects provides @sum, @avg, etc array operators. ERXArrayUtilities adds quite a few more:
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9 **SortOperator:** Define an NSArray.Operator for the key //sort//.
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11 This allows for key value paths like:
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13 {{panel}}
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15 myArray.valueForKey("@sort.firstName");
16
17 {{/panel}}
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19 myArray.valueForKey("@sort.lastName,firstName");
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21 Which in the first case would return myArray sorted ascending by first name and the second case
22 by lastName and then by firstName.
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24 Other sort operators registered are: @sortAsc, @sortDesc, @sortInsensitiveAsc, @sortInsensitiveDesc
25
26 **FetchSpecOperator:** Define an NSArray.Operator for the key //fetchSpec//.
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28 This allows for key value paths like:
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30 {{panel}}
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32 myArray.valueForKey("@fetchSpec.fetchUsers");
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34 {{/panel}}
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36 Which in this case would return myArray filtered and sorted by the
37 EOFetchSpecification named "fetchUsers" which must be a model-based fetchspec in the
38 first object's entity.
39
40 **FlattenOperator:** Define an NSArray.Operator for the key //flatten//.
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42 This allows for key value paths like:
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44 {{panel}}
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46 myArray.valueForKey("@flatten");
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48 {{/panel}}
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50 Which in this case would return myArray flattened if myArray is an NSArray of NSArrays (of NSArrays etc).
51
52 **IsEmptyOperator:** Define an NSArray.Operator for the key //isEmpty//.
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54 This allows for key value paths like:
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56 {{panel}}
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58 myArray.valueForKey("@isEmpty");
59
60 {{/panel}}
61
62 **SubarrayWithRangeOperator:** Define an NSArray.Operator for the key //subarrayWithRange//.
63
64 This allows for key value paths like:
65
66 {{panel}}
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68 myArray.valueForKey("@subarrayWithRange.3-20");
69
70 {{/panel}}
71
72 **UniqueOperator:** Define an NSArray.Operator for the key //unique//.
73
74 This allows for key value paths like:
75
76 {{panel}}
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78 myArray.valueForKeyPath("@unique.someOtherPath");
79
80 {{/panel}}
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82 Which in this case would return only those objects which are unique in myArray.
83
84 **RemoveNullValuesOperator:** Define an NSArray.Operator for the key //removeNullValues//.
85
86 This allows for key value paths like:
87
88 {{panel}}
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90 myArray.valueForKeyPath("@removeNullValues.someOtherPath");
91
92 {{/panel}}
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94 Which in this case would return myArray without the occurrences of NSKeyValueCoding.Null.
95
96 **ObjectAtIndexOperator:** Define an NSArray.Operator for the key //objectAtIndex//.
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98 This allows for key value paths like:
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100 {{panel}}
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102 myArray.valueForKey("@objectAtIndex.3.firstName");
103
104 {{/panel}}
105
106 **AvgNonNullOperator:** Define an NSArray.Operator for the key //avgNonNull//.
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108 This allows for key value paths like:
109
110 {{panel}}
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112 myArray.valueForKey("@avgNonNull.revenue");
113
114 {{/panel}}
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116 which will sum up all values and divide by the number of nun-null entries.
117
118 **ReverseOperator:** Define an NSArray.Operator for the key //reverse//.
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120 This allows for key value paths like:
121
122 {{panel}}
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124 myArray.valueForKey("@reverse.someMorePath");
125
126 {{/panel}}
127
128 which return a reversed result as to you would normally get.
129
130 **MedianOperator:** Define an NSArray.Operator for the key //median//.
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132 This allows for key value paths like:
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134 {{panel}}
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136 myArray.valueForKey("@median.someMorePath");
137
138 {{/panel}}
139
140 which return the median of the array elements at the given key path.
141 The median is the value for which half of the elements are above and half the elements are below.
142 As such, an array sort is needed and this might be very costly depending of the size of the array.
143
144 Category:WebObjects