睡不着，講講最近做的一個項目的架構的一部分吧，這是一個項目管理系統，支持動態屬性，也就是說一個資料
– 例如“項目”、“任務”就是資料，資料的屬性
– 例如“名稱”、“時間”都是可以在系統運行時動態增刪改的。
本文就講一講在.NET和SQL Server里實現動態屬性的方法，雖然演示代碼都是C#，但我相信可以很容易的移植到Java中。
首先定義幾個名詞：
資料 – 是對於系統最終用戶來說其要維護的數據，例如“項目”、“任務”信息等。
屬性 – 即資料的一個方面的數據，或者稱作字段，在C#代碼里應該就是一個Property。
元數據 – 是解釋屬性的方式，有時我也會把它稱作元屬性。
屬性和元數據的關系呢，可以參照Excel的實現來理解，好比說我們在一個單元格里輸入了一個數據，實際上我們是輸入了一個字符串，假設是“1”，當我們設置Excel使用“數字”格式呈現時，那用戶在單元格里實際看到的是“1.0”，當我們設置Excel使用“日期”格式呈現時，那用戶在單元格里看到的可能就是“1900-1-1”。這里，字符串“1”就是屬性，而元數據實際上就類似Excel里的格式。
對於資料來說，它只保存一個屬性列表，而屬性有一個外鍵指向定義其格式的元數據，下面是資料、屬性和元數據的C#定義：
資料
1
public
class GenericDynamicPropertiesEntity : IDynamicPropertiesTable, ISupportDefaultProperties
2 {
3 public GenericDynamicPropertiesEntity()
4 {
5 Properties = new List<Property>();
6 this.FillDefaultProperties();
7 }
8
9 public string Get( string name)
10 {
11 var property = this.Property(name, false);
12 if (property != null)
13 {
14 return property.Value;
15 }
16 else
17 {
18 return null;
19 }
20 }
21
22 public Property Get(MetaProperty meta)
23 {
24 var property = this.Property(meta.Title, false);
25 if (property != null)
26 {
27 return this.Property(meta.Title, false);
28 }
29 else
30 {
31 return null;
32 }
33 }
34 public void Set( string name, string value)
35 {
36 var property = this.Property(name, true);
37 if (property.Meta.Valid(value))
38 property.Value = value;
39 else
40 throw new InvalidValueException( string.Format( " 字段\"{0}\"的值\"{1}\"無效，字段\"{0}\"的類型是\"{2}\", 期望值的格式是\"{3}\" ",
41 name, value, property.Meta.Type, property.Meta.ExpectedFormat));
42 }
43
44 public void Set( string name, double value)
45 {
46 var property = this.Property(name, true);
47 if (property.Meta.Valid(value))
48 property.Value = value.ToString();
49 else
50 throw new InvalidValueException( string.Format( " 字段\"{0}\"的值\"{1}\"無效，字段\"{0}\"的類型是\"{2}\", 期望值的格式是\"{3}\" ",
51 name, value, property.Meta.Type, property.Meta.ExpectedFormat));
52 }
53
54 public List<Property> Properties { get; private set; }
55
56 [DataMember]
57 public Guid Id { get; set; }
58
59 public static T New<T>() where T : GenericDynamicPropertiesEntity, new()
60 {
61 return new T()
62 {
63 Id = Guid.NewGuid()
64 };
65 }
66
67 protected void SetClassValue<T>( string propertyName, T member, T value)
68 {
69 member = value;
70 Set(propertyName, value != null ? value.ToJson() : null);
71 }
72
73 protected void SetNullableDateTime<T>( string propertyName, T? member, T? value) where T : struct
74 {
75 member = value;
76 Set(propertyName, value.HasValue ? value.Value.ToString() : null);
77 }
78
79 protected void SetDateTime( string propertyName, DateTime member, DateTime value)
80 {
81 member = value;
82 Set(propertyName, value.ToString());
83 }
84
85 protected void SetSingle( string propertyName, float member, float value)
86 {
87 member = value;
88 Set(propertyName, value);
89 }
90
91 protected void SetPrimeValue<T>( string propertyName, T member, T value) where T : struct
92 {
93 member = value;
94 Set(propertyName, value.ToString());
95 }
96
97 protected DateTime? GetNullableDateTime( string propertyName, DateTime? date)
98 {
99 if (!date.HasValue)
100 {
101 var value = Get(propertyName);
102 if (value != null)
103 {
104 date = DateTime.Parse(value);
105 }
106 }
107
108 return date;
109 }
110
111 protected float GetSingle( string propertyName, float member)
112 {
113 if ( float.IsNaN(member))
114 {
115 var property = this.Property(propertyName, false);
116 if (property != null)
117 {
118 member = Single.Parse(property.Value);
119 }
120 }
121
122 return member;
123 }
124
125 protected DateTime GetDateTime( string propertyName, DateTime member)
126 {
127 if (member == DateTime.MinValue)
128 {
129 var value = Get(propertyName);
130 if (value != null)
131 {
132 member = DateTime.Parse(value);
133 return member;
134 }
135 else
136 {
137 throw new PropertyNotFoundException( string.Format( " 在Id為\"{0}\"的對象里找不到名為\"{1}\"的屬性！ ", Id, propertyName));
138 }
139 }
140 else
141 {
142 return member;
143 }
144 }
145
146 public DateTime? ClosedDate
147 {
148 get;
149 set;
150 }
151
152 public DateTime OpenDate
153 {
154 get;
155 set;
156 }
157
158 public DateTime LastModified
159 {
160 get;
161 set;
162 }
163
164 public string Creator
165 {
166 get;
167 set;
168 }
169
170 public string LastModifiedBy
171 {
172 get;
173 set;
174 }
175 }
2 {
3 public GenericDynamicPropertiesEntity()
4 {
5 Properties = new List<Property>();
6 this.FillDefaultProperties();
7 }
8
9 public string Get( string name)
10 {
11 var property = this.Property(name, false);
12 if (property != null)
13 {
14 return property.Value;
15 }
16 else
17 {
18 return null;
19 }
20 }
21
22 public Property Get(MetaProperty meta)
23 {
24 var property = this.Property(meta.Title, false);
25 if (property != null)
26 {
27 return this.Property(meta.Title, false);
28 }
29 else
30 {
31 return null;
32 }
33 }
34 public void Set( string name, string value)
35 {
36 var property = this.Property(name, true);
37 if (property.Meta.Valid(value))
38 property.Value = value;
39 else
40 throw new InvalidValueException( string.Format( " 字段\"{0}\"的值\"{1}\"無效，字段\"{0}\"的類型是\"{2}\", 期望值的格式是\"{3}\" ",
41 name, value, property.Meta.Type, property.Meta.ExpectedFormat));
42 }
43
44 public void Set( string name, double value)
45 {
46 var property = this.Property(name, true);
47 if (property.Meta.Valid(value))
48 property.Value = value.ToString();
49 else
50 throw new InvalidValueException( string.Format( " 字段\"{0}\"的值\"{1}\"無效，字段\"{0}\"的類型是\"{2}\", 期望值的格式是\"{3}\" ",
51 name, value, property.Meta.Type, property.Meta.ExpectedFormat));
52 }
53
54 public List<Property> Properties { get; private set; }
55
56 [DataMember]
57 public Guid Id { get; set; }
58
59 public static T New<T>() where T : GenericDynamicPropertiesEntity, new()
60 {
61 return new T()
62 {
63 Id = Guid.NewGuid()
64 };
65 }
66
67 protected void SetClassValue<T>( string propertyName, T member, T value)
68 {
69 member = value;
70 Set(propertyName, value != null ? value.ToJson() : null);
71 }
72
73 protected void SetNullableDateTime<T>( string propertyName, T? member, T? value) where T : struct
74 {
75 member = value;
76 Set(propertyName, value.HasValue ? value.Value.ToString() : null);
77 }
78
79 protected void SetDateTime( string propertyName, DateTime member, DateTime value)
80 {
81 member = value;
82 Set(propertyName, value.ToString());
83 }
84
85 protected void SetSingle( string propertyName, float member, float value)
86 {
87 member = value;
88 Set(propertyName, value);
89 }
90
91 protected void SetPrimeValue<T>( string propertyName, T member, T value) where T : struct
92 {
93 member = value;
94 Set(propertyName, value.ToString());
95 }
96
97 protected DateTime? GetNullableDateTime( string propertyName, DateTime? date)
98 {
99 if (!date.HasValue)
100 {
101 var value = Get(propertyName);
102 if (value != null)
103 {
104 date = DateTime.Parse(value);
105 }
106 }
107
108 return date;
109 }
110
111 protected float GetSingle( string propertyName, float member)
112 {
113 if ( float.IsNaN(member))
114 {
115 var property = this.Property(propertyName, false);
116 if (property != null)
117 {
118 member = Single.Parse(property.Value);
119 }
120 }
121
122 return member;
123 }
124
125 protected DateTime GetDateTime( string propertyName, DateTime member)
126 {
127 if (member == DateTime.MinValue)
128 {
129 var value = Get(propertyName);
130 if (value != null)
131 {
132 member = DateTime.Parse(value);
133 return member;
134 }
135 else
136 {
137 throw new PropertyNotFoundException( string.Format( " 在Id為\"{0}\"的對象里找不到名為\"{1}\"的屬性！ ", Id, propertyName));
138 }
139 }
140 else
141 {
142 return member;
143 }
144 }
145
146 public DateTime? ClosedDate
147 {
148 get;
149 set;
150 }
151
152 public DateTime OpenDate
153 {
154 get;
155 set;
156 }
157
158 public DateTime LastModified
159 {
160 get;
161 set;
162 }
163
164 public string Creator
165 {
166 get;
167 set;
168 }
169
170 public string LastModifiedBy
171 {
172 get;
173 set;
174 }
175 }
屬性
1
///
<summary>
2 /// 資料的屬性
3 /// </summary>
4 public class Property : ITable
5 {
6 /// <summary>
7 /// 獲取和設置資料的值
8 /// </summary>
9 /// <remarks>
10 /// 對於普通類型，例如float等類型直接就保存其ToString的返回結果
11 /// 對於復雜類型，則保存其json格式的對象
12 /// </remarks>
13 // TODO: 第二版 - 需要考慮國際化情形下，屬性有多個值的情形！
14 public string Value { get; set; }
15
16 /// <summary>
17 /// 獲取和設置屬性的Id
18 /// </summary>
19 public Guid Id { get; set; }
20
21 public MetaProperty Meta { get; set; }
22
23 /// <summary>
24 /// 獲取和設置該屬性對應的元數據Id
25 /// </summary>
26 public Guid MetaId { get; set; }
27
28 /// <summary>
29 /// 該屬性對應的資料的編號
30 /// </summary>
31 public Guid EntityId { get; set; }
32
33 /// <summary>
34 /// 獲取和設置該屬性所屬的資料
35 /// </summary>
36 public GenericDynamicPropertiesEntity Entity { get; set; }
37 }
2 /// 資料的屬性
3 /// </summary>
4 public class Property : ITable
5 {
6 /// <summary>
7 /// 獲取和設置資料的值
8 /// </summary>
9 /// <remarks>
10 /// 對於普通類型，例如float等類型直接就保存其ToString的返回結果
11 /// 對於復雜類型，則保存其json格式的對象
12 /// </remarks>
13 // TODO: 第二版 - 需要考慮國際化情形下，屬性有多個值的情形！
14 public string Value { get; set; }
15
16 /// <summary>
17 /// 獲取和設置屬性的Id
18 /// </summary>
19 public Guid Id { get; set; }
20
21 public MetaProperty Meta { get; set; }
22
23 /// <summary>
24 /// 獲取和設置該屬性對應的元數據Id
25 /// </summary>
26 public Guid MetaId { get; set; }
27
28 /// <summary>
29 /// 該屬性對應的資料的編號
30 /// </summary>
31 public Guid EntityId { get; set; }
32
33 /// <summary>
34 /// 獲取和設置該屬性所屬的資料
35 /// </summary>
36 public GenericDynamicPropertiesEntity Entity { get; set; }
37 }
元數據
1
public
class MetaProperty : INamedTable, ISecret
2 {
3 public Guid Id { get; set; }
4
5 public string BelongsToMaterial { get; set; }
6
7 public String Title { get; set; }
8
9 public string Type { get; set; }
10
11 public string DefaultValue { get; private set; }
12
13 /// <summary>
14 /// 獲取和設置屬性的權限
15 /// </summary>
16 public int Permission { get; set; }
17
18 public virtual string ExpectedFormat { get { return string.Empty; } }
19
20 public virtual bool Valid( string value)
21 {
22 return true;
23 }
24
25 public virtual bool Valid( double value)
26 {
27 return true;
28 }
29
30 public static MetaProperty NewString( string name)
31 {
32 return new MetaProperty()
33 {
34 Id = Guid.NewGuid(),
35 Title = name,
36 Type = Default.MetaProperty.Type.String,
37 Permission = Default.Permission.Mask
38 };
39 }
40
41 public static MetaProperty NewNumber( string name, double defaultValue = 0.0)
42 {
43 return new MetaProperty()
44 {
45 Id = Guid.NewGuid(),
46 Title = name,
47 Type = Default.MetaProperty.Type.Number,
48 Permission = Default.Permission.Mask,
49 DefaultValue = defaultValue.ToString()
50 };
51 }
52
53 public static MetaProperty NewAddress( string name)
54 {
55 return new MetaProperty()
56 {
57 Id = Guid.NewGuid(),
58 Title = name,
59 Type = Default.MetaProperty.Type.Address,
60 Permission = Default.Permission.Mask
61 };
62 }
63
64 public static MetaProperty NewRelationship( string name)
65 {
66 return new MetaProperty()
67 {
68 Id = Guid.NewGuid(),
69 Title = name,
70 Type = Default.MetaProperty.Type.Relationship,
71 Permission = Default.Permission.Mask
72 };
73 }
74
75 public static MetaProperty NewDateTime( string name)
76 {
77 return new MetaProperty()
78 {
79 Id = Guid.NewGuid(),
80 Title = name,
81 Type = Default.MetaProperty.Type.DateTime,
82 Permission = Default.Permission.Mask
83 };
84 }
85
86 public static MetaProperty NewDate( string name)
87 {
88 return new MetaProperty()
89 {
90 Id = Guid.NewGuid(),
91 Title = name,
92 Type = Default.MetaProperty.Type.Date,
93 Permission = Default.Permission.Mask
94 };
95 }
96
97 public static MetaProperty NewTime( string name)
98 {
99 return new MetaProperty()
100 {
101 Id = Guid.NewGuid(),
102 Title = name,
103 Type = Default.MetaProperty.Type.Time,
104 Permission = Default.Permission.Mask
105 };
106 }
107
108 public static MetaProperty NewUser( string name)
109 {
110 return new MetaProperty()
111 {
112 Id = Guid.NewGuid(),
113 Title = name,
114 Type = Default.MetaProperty.Type.User,
115 Permission = Default.Permission.Mask
116 };
117 }
118
119 public static MetaProperty NewUrl( string name)
120 {
121 return new UrlMetaProperty()
122 {
123 Id = Guid.NewGuid(),
124 Title = name,
125 Type = Default.MetaProperty.Type.Url,
126 Permission = Default.Permission.Mask
127 };
128 }
129
130 public static MetaProperty NewTag( string name)
131 {
132 return new MetaProperty()
133 {
134 Id = Guid.NewGuid(),
135 Title = name,
136 Type = Default.MetaProperty.Type.Tag,
137 Permission = Default.Permission.Mask
138 };
139 }
140 }
141
142 public class MetaProperties : List<MetaProperty>
143 {
144 public MetaProperty Find( string name)
145 {
146 return this.SingleOrDefault(p => String.Compare(p.Title, name) == 0);
147 }
148 }
2 {
3 public Guid Id { get; set; }
4
5 public string BelongsToMaterial { get; set; }
6
7 public String Title { get; set; }
8
9 public string Type { get; set; }
10
11 public string DefaultValue { get; private set; }
12
13 /// <summary>
14 /// 獲取和設置屬性的權限
15 /// </summary>
16 public int Permission { get; set; }
17
18 public virtual string ExpectedFormat { get { return string.Empty; } }
19
20 public virtual bool Valid( string value)
21 {
22 return true;
23 }
24
25 public virtual bool Valid( double value)
26 {
27 return true;
28 }
29
30 public static MetaProperty NewString( string name)
31 {
32 return new MetaProperty()
33 {
34 Id = Guid.NewGuid(),
35 Title = name,
36 Type = Default.MetaProperty.Type.String,
37 Permission = Default.Permission.Mask
38 };
39 }
40
41 public static MetaProperty NewNumber( string name, double defaultValue = 0.0)
42 {
43 return new MetaProperty()
44 {
45 Id = Guid.NewGuid(),
46 Title = name,
47 Type = Default.MetaProperty.Type.Number,
48 Permission = Default.Permission.Mask,
49 DefaultValue = defaultValue.ToString()
50 };
51 }
52
53 public static MetaProperty NewAddress( string name)
54 {
55 return new MetaProperty()
56 {
57 Id = Guid.NewGuid(),
58 Title = name,
59 Type = Default.MetaProperty.Type.Address,
60 Permission = Default.Permission.Mask
61 };
62 }
63
64 public static MetaProperty NewRelationship( string name)
65 {
66 return new MetaProperty()
67 {
68 Id = Guid.NewGuid(),
69 Title = name,
70 Type = Default.MetaProperty.Type.Relationship,
71 Permission = Default.Permission.Mask
72 };
73 }
74
75 public static MetaProperty NewDateTime( string name)
76 {
77 return new MetaProperty()
78 {
79 Id = Guid.NewGuid(),
80 Title = name,
81 Type = Default.MetaProperty.Type.DateTime,
82 Permission = Default.Permission.Mask
83 };
84 }
85
86 public static MetaProperty NewDate( string name)
87 {
88 return new MetaProperty()
89 {
90 Id = Guid.NewGuid(),
91 Title = name,
92 Type = Default.MetaProperty.Type.Date,
93 Permission = Default.Permission.Mask
94 };
95 }
96
97 public static MetaProperty NewTime( string name)
98 {
99 return new MetaProperty()
100 {
101 Id = Guid.NewGuid(),
102 Title = name,
103 Type = Default.MetaProperty.Type.Time,
104 Permission = Default.Permission.Mask
105 };
106 }
107
108 public static MetaProperty NewUser( string name)
109 {
110 return new MetaProperty()
111 {
112 Id = Guid.NewGuid(),
113 Title = name,
114 Type = Default.MetaProperty.Type.User,
115 Permission = Default.Permission.Mask
116 };
117 }
118
119 public static MetaProperty NewUrl( string name)
120 {
121 return new UrlMetaProperty()
122 {
123 Id = Guid.NewGuid(),
124 Title = name,
125 Type = Default.MetaProperty.Type.Url,
126 Permission = Default.Permission.Mask
127 };
128 }
129
130 public static MetaProperty NewTag( string name)
131 {
132 return new MetaProperty()
133 {
134 Id = Guid.NewGuid(),
135 Title = name,
136 Type = Default.MetaProperty.Type.Tag,
137 Permission = Default.Permission.Mask
138 };
139 }
140 }
141
142 public class MetaProperties : List<MetaProperty>
143 {
144 public MetaProperty Find( string name)
145 {
146 return this.SingleOrDefault(p => String.Compare(p.Title, name) == 0);
147 }
148 }
維護資料時，使用類似下面的代碼就可以給資料創建無限多的屬性，可以事先、事后給屬性關聯元數據，以便定義編輯和顯示方式（里面用到一些Ioc和Mock）：
1 [TestMethod]
2 public void 驗證客戶資料的動態屬性的可行性()
3 {
4 var rep = new MemoryContext();
5 MemoryMetaSet metas = new MemoryMetaSet();
6 metas.Add( typeof(Customer), MetaProperty.NewString( " 姓名 "));
7 metas.Add( typeof(Customer), MetaProperty.NewNumber( " 年齡 "));
8 metas.Add( typeof(Customer), MetaProperty.NewAddress( " 地址 "));
9 metas.Add( typeof(Customer), MetaProperty.NewRelationship( " 同事 "));
10 rep.MetaSet = metas;
11
12 var builder = new ContainerBuilder();
13 var mocks = new Mockery();
14 var user = mocks.NewMock<IUser>();
15 Expect.AtLeastOnce.On(user).GetProperty( " Email ").Will(Return.Value(DEFAULT_USER_EMAIL));
16
17 builder.RegisterInstance(user).As<IUser>();
18 builder.RegisterInstance(rep).As<IContext>();
19 var back = IocHelper.Container;
20 try
21 {
22 IocHelper.Container = builder.Build();
23
24 var customer = Customer.New<Customer>();
25 customer.Set( " 姓名 ", " XXX ");
26 customer.Set( " 年齡 ", 28);
27 customer.Set( " 地址 ", " ZZZZZZZZZZZZZZZZZZZZZZ ");
28
29 var colleague = Customer.New<Customer>();
30 colleague.Set( " 姓名 ", " YYY ");
31
32 // 對於稍微復雜一點的對象，我們可以用json對象
33 customer.Set( " 同事 ", Relationship.Colleague(customer, colleague).ToString());
34
35 Assert.AreEqual( " XXX ", customer.Get( " 姓名 "));
36 }
37 finally
38 {
39 IocHelper.Container = back;
40 }
41 }
2 public void 驗證客戶資料的動態屬性的可行性()
3 {
4 var rep = new MemoryContext();
5 MemoryMetaSet metas = new MemoryMetaSet();
6 metas.Add( typeof(Customer), MetaProperty.NewString( " 姓名 "));
7 metas.Add( typeof(Customer), MetaProperty.NewNumber( " 年齡 "));
8 metas.Add( typeof(Customer), MetaProperty.NewAddress( " 地址 "));
9 metas.Add( typeof(Customer), MetaProperty.NewRelationship( " 同事 "));
10 rep.MetaSet = metas;
11
12 var builder = new ContainerBuilder();
13 var mocks = new Mockery();
14 var user = mocks.NewMock<IUser>();
15 Expect.AtLeastOnce.On(user).GetProperty( " Email ").Will(Return.Value(DEFAULT_USER_EMAIL));
16
17 builder.RegisterInstance(user).As<IUser>();
18 builder.RegisterInstance(rep).As<IContext>();
19 var back = IocHelper.Container;
20 try
21 {
22 IocHelper.Container = builder.Build();
23
24 var customer = Customer.New<Customer>();
25 customer.Set( " 姓名 ", " XXX ");
26 customer.Set( " 年齡 ", 28);
27 customer.Set( " 地址 ", " ZZZZZZZZZZZZZZZZZZZZZZ ");
28
29 var colleague = Customer.New<Customer>();
30 colleague.Set( " 姓名 ", " YYY ");
31
32 // 對於稍微復雜一點的對象，我們可以用json對象
33 customer.Set( " 同事 ", Relationship.Colleague(customer, colleague).ToString());
34
35 Assert.AreEqual( " XXX ", customer.Get( " 姓名 "));
36 }
37 finally
38 {
39 IocHelper.Container = back;
40 }
41 }
因為動態屬性事先不知道其格式，為了實現搜索功能，無法在編寫程序的時候拼接查詢用的SQL語句，因此我抽象了一層，定義了一個小的查詢語法，寫了一個小小的編譯器將查詢語句轉化成SQL語句，實現了對動態屬性的查詢功能，請看下面的測試用例：
1 [TestMethod]
2 public void 測試簡單的條件組合查詢()
3 {
4 using ( var context = IocHelper.Container.Resolve<IContext>())
5 {
6 var customer = Customer.New<Customer>();
7 customer.Set( " 姓名 ", " 測試簡單的條件組合查詢 ");
8 customer.Set( " 年齡 ", 28);
9 customer.Set( " 地址 ", " 上海市浦東新區 ");
10 context.Customers.Add(customer);
11 context.SaveChanges();
12
13 var result = context.Customers.Query( " (AND (姓名='測試簡單的條件組合查詢') " +
14 " (年齡 介於 1 到 30) " +
15 " ) ");
16 Assert.IsTrue(result.Count() > 0);
17 var actual = result.First();
18 Assert.AreEqual( " 測試簡單的條件組合查詢 ", actual.Get( " 姓名 "));
19 Assert.AreEqual( " 28 ", actual.Get( " 年齡 "));
20 }
21 }
2 public void 測試簡單的條件組合查詢()
3 {
4 using ( var context = IocHelper.Container.Resolve<IContext>())
5 {
6 var customer = Customer.New<Customer>();
7 customer.Set( " 姓名 ", " 測試簡單的條件組合查詢 ");
8 customer.Set( " 年齡 ", 28);
9 customer.Set( " 地址 ", " 上海市浦東新區 ");
10 context.Customers.Add(customer);
11 context.SaveChanges();
12
13 var result = context.Customers.Query( " (AND (姓名='測試簡單的條件組合查詢') " +
14 " (年齡 介於 1 到 30) " +
15 " ) ");
16 Assert.IsTrue(result.Count() > 0);
17 var actual = result.First();
18 Assert.AreEqual( " 測試簡單的條件組合查詢 ", actual.Get( " 姓名 "));
19 Assert.AreEqual( " 28 ", actual.Get( " 年齡 "));
20 }
21 }
上面測試用例里的查詢語句：
(AND (姓名='測試簡單的條件組合查詢') (年齡 介於 1 到 30) )
經過Query函數的編譯之后，會轉化成下面的兩段SQL語句：
SELECT e.
*, p.
*
FROM Properties
AS p
INNER
JOIN GenericDynamicPropertiesEntities
AS e
ON p.EntityId
= e.Id
INNER
JOIN MetaSet
AS m
ON p.MetaId
= m.Id
WHERE ((
CASE
WHEN m.Type
=
'
日期時間型
'
AND (
CONVERT(
datetime, p.Value)
= N
'
測試簡單的條件組合查詢
')
AND (m.Title
= N
'
姓名
')
THEN
1
WHEN m.Type
=
'
字符串
'
AND (p.Value
= N
'
測試簡單的條件組合查詢
')
AND (m.Title
= N
'
姓名
')
THEN
1
ELSE
0
END
=
1))
SELECT e.
*, p.
*
FROM Properties
AS p
INNER
JOIN GenericDynamicPropertiesEntities
AS e
ON p.EntityId
= e.Id
INNER
JOIN MetaSet
AS m
ON p.MetaId
= m.Id
WHERE ((
CASE
WHEN m.Type
=
'
數字型
'
AND (
CONVERT(
int, p.Value)
BETWEEN
1
AND
30)
AND (m.Title
= N
'
年齡
')
THEN
1
WHEN m.Type
=
'
日期時間型
'
AND (
CONVERT(
datetime, p.Value)
BETWEEN N
'
1
'
AND N
'
30
')
AND (m.Title
= N
'
年齡
')
THEN
1
ELSE
0
END
=
1))
然后分別執行查詢並在業務層將求解查詢結果的交集，也許是可以直接生成一條SQL語句交給數據庫處理成最精簡的結果再返回的，但是因為開發時間、以及目標客戶的關系，暫時沒有花精力做這個優化。
當然上面的查詢語句寫起來還比較復雜，因此我做了一個界面方便用戶編輯查詢條件，另外對資料屬性的編輯、元數據維護等內容，后面再寫文章說，蚊子太多了……