BlankClassSoDocsWillBeGenerated

1 import db_constraints;
2 
3 class Brand
4 {
5     private int _Id;
6     // marking Id with not null and primary key
7     @NotNull @PrimaryKeyColumn
8     @property int Id()
9     {
10         return _Id;
11     }
12     @property void Id(int value)
13     {
14         setter(_Id, value);
15     }
16 
17     private string _BrandName;
18     // marking BrandName with UniqueConstraintColumn
19     // so the collection will know this property should be
20     // unique for all records
21     @UniqueConstraintColumn!("Unique")
22     @property string BrandName()
23     {
24         return _BrandName;
25     }
26     @property void BrandName(string value)
27     {
28         setter(_BrandName, value);
29     }
30 
31     this(int Id_, string BrandName_)
32     {
33         this._Id = Id_;
34         this._BrandName = BrandName_;
35         // do not forget to initialize the keyed item!
36         initializeKeyedItem();
37     }
38 
39     // do not forget to add in the keyed item!
40     mixin KeyedItem!();
41 }
42 
43 // this is what I call the plural class
44 // or table class. This is the collection
45 // of rows (in this example Brands).
46 class Brands
47 {
48     // this mixin already does the
49     // initializations and every method
50     // I want for this tutorial so I
51     // do not need anything else.
52     mixin KeyedCollection!(Brand);
53 }
54 
55 import std.exception : assertNotThrown, assertThrown;
56 
57 // UNIQUE constraint
58 {
59     // we can start by putting two records into the collection.
60     // now brands holds a record for Coca Cola and Pepsi
61     auto brands = new Brands([new Brand(1, "Coca Cola"),
62                               new Brand(2, "Pepsi")]);
63 
64     auto anotherPepsi = new Brand(3, "Pepsi");
65     // if we try to add another record that has Pepsi for
66     // the brand name we will get a unique constraint exception
67     assertThrown!UniqueConstraintException(brands.add(anotherPepsi));
68 
69     // we can see if the new record will violate any unique constraints
70     // before we add it to the collection by using violatesUniqueConstraints
71     assert(brands.violatesUniqueConstraints(anotherPepsi));
72 }
73 
74 // PRIMARY KEY constraint
75 {
76     // the primary key is unique and not null
77     // by default we can use the primary key to look up
78     // records in the collection
79     auto brands = new Brands([new Brand(1, "Coca Cola"),
80                               new Brand(2, "Pepsi")]);
81 
82     // since Pepsi's Id is the primary key we can use 2 to find pepsi
83     assert(brands[2].BrandName == "Pepsi");
84     assert(brands[2].Id == 2);
85     // this is because brands is really an associative array that uses the
86     // primary key in this case as the AA key. We can check if the
87     // collection already contains a primary key of 2 by using contains
88     assert(brands.contains(2));
89     // and does not contain 4
90     assert(!brands.contains(4));
91     // if you try to get an item that is not there you will get an exception
92     assertThrown!KeyedException(brands[4].BrandName);
93 
94     // lets add two more records
95     brands ~= [new Brand(3, "Sun"), new Brand(4, "Oracle")];
96 
97     // now it does contain 4
98     assert(brands.contains(4));
99     assertNotThrown!KeyedException(brands[4].BrandName);
100 }