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1 using System;
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2 using System.Linq;
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3 using System.Linq.Expressions;
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4
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5 namespace BLToolkit.Data.Linq.Builder
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6 {
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7 using BLToolkit.Linq;
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8 using Data.Sql;
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9 using Reflection;
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10
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11 class AggregationBuilder : MethodCallBuilder
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12 {
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13 public static string[] MethodNames = new[] { "Average", "Min", "Max", "Sum" };
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14
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15 protected override bool CanBuildMethodCall(ExpressionBuilder builder, MethodCallExpression methodCall, BuildInfo buildInfo)
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16 {
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17 return methodCall.IsQueryable(MethodNames);
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18 }
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19
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20 protected override IBuildContext BuildMethodCall(ExpressionBuilder builder, MethodCallExpression methodCall, BuildInfo buildInfo)
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21 {
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22 var sequence = builder.BuildSequence(new BuildInfo(buildInfo, methodCall.Arguments[0]));
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23
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24 if (sequence.SqlQuery.Select.IsDistinct ||
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25 sequence.SqlQuery.Select.TakeValue != null ||
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26 sequence.SqlQuery.Select.SkipValue != null ||
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27 !sequence.SqlQuery.GroupBy.IsEmpty)
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28 {
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29 sequence = new SubQueryContext(sequence);
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30 }
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31
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32 if (!sequence.SqlQuery.OrderBy.IsEmpty)
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33 {
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34 if (sequence.SqlQuery.Select.TakeValue == null && sequence.SqlQuery.Select.SkipValue == null)
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35 sequence.SqlQuery.OrderBy.Items.Clear();
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36 else
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37 sequence = new SubQueryContext(sequence);
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38 }
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39
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40 var context = new AggregationContext(buildInfo.Parent, sequence, methodCall);
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41 var sql = sequence.ConvertToSql(null, 0, ConvertFlags.Field).Select(_ => _.Sql).ToArray();
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42
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43 if (sql.Length == 1 && sql[0] is SqlQuery)
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44 {
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45 var query = (SqlQuery)sql[0];
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46
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47 if (query.Select.Columns.Count == 1)
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48 {
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49 var join = SqlQuery.OuterApply(query);
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50 context.SqlQuery.From.Tables[0].Joins.Add(join.JoinedTable);
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51 sql[0] = query.Select.Columns[0];
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52 }
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53 }
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54
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55 context.Sql = context.SqlQuery;
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56 context.FieldIndex = context.SqlQuery.Select.Add(
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57 new SqlFunction(methodCall.Type, methodCall.Method.Name, sql));
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58
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59 return context;
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60 }
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61
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62 protected override SequenceConvertInfo Convert(
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63 ExpressionBuilder builder, MethodCallExpression methodCall, BuildInfo buildInfo, ParameterExpression param)
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64 {
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65 return null;
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66 }
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67
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68 class AggregationContext : SequenceContextBase
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69 {
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70 public AggregationContext(IBuildContext parent, IBuildContext sequence, MethodCallExpression methodCall)
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71 : base(parent, sequence, null)
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72 {
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73 _returnType = methodCall.Method.ReturnType;
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74 _methodName = methodCall.Method.Name;
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75 }
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76
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77 readonly string _methodName;
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78 readonly Type _returnType;
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79 private SqlInfo[] _index;
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80
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81 public int FieldIndex;
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82 public ISqlExpression Sql;
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83
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84 static object CheckNullValue(object value, object context)
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85 {
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86 if (value == null || value is DBNull)
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87 throw new InvalidOperationException(string.Format("Function {0} returns non-nullable value, but result is NULL. Use nullable version of the function instead.", context));
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88
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89 return value;
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90 }
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91
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92 public override void BuildQuery<T>(Query<T> query, ParameterExpression queryParameter)
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93 {
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94 var expr = BuildExpression(FieldIndex);
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95 var mapper = Builder.BuildMapper<object>(expr);
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96
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97 query.SetElementQuery(mapper.Compile());
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98 }
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99
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100 public override Expression BuildExpression(Expression expression, int level)
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101 {
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102 return BuildExpression(ConvertToIndex(expression, level, ConvertFlags.Field)[0].Index);
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103 }
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104
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105 Expression BuildExpression(int fieldIndex)
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106 {
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107 Expression expr;
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108
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109 if (_returnType.IsClass || _methodName == "Sum" || TypeHelper.IsNullableType(_returnType))
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110 {
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111 expr = Builder.BuildSql(_returnType, fieldIndex);
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112 }
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113 else
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114 {
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115 expr = Builder.BuildSql(
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116 _returnType,
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117 fieldIndex,
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118 ReflectionHelper.Expressor<object>.MethodExpressor(o => CheckNullValue(o, o)),
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119 Expression.Constant(_methodName));
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120 }
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121
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122 return expr;
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123 }
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124
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125 public override SqlInfo[] ConvertToSql(Expression expression, int level, ConvertFlags flags)
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126 {
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127 switch (flags)
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128 {
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129 case ConvertFlags.All :
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130 case ConvertFlags.Key :
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131 case ConvertFlags.Field : return Sequence.ConvertToSql(expression, level + 1, flags);
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132 }
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133
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134 throw new InvalidOperationException();
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135 }
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136
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137 public override SqlInfo[] ConvertToIndex(Expression expression, int level, ConvertFlags flags)
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138 {
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139 switch (flags)
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140 {
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141 case ConvertFlags.Field :
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142 return _index ?? (_index = new[]
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143 {
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144 new SqlInfo { Query = Parent.SqlQuery, Index = Parent.SqlQuery.Select.Add(Sql), Sql = Sql, }
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145 });
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146 }
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147
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148 throw new InvalidOperationException();
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149 }
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150
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151 public override IsExpressionResult IsExpression(Expression expression, int level, RequestFor requestFlag)
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152 {
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153 switch (requestFlag)
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154 {
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155 case RequestFor.Root : return new IsExpressionResult(Lambda != null && expression == Lambda.Parameters[0]);
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156 case RequestFor.Expression : return IsExpressionResult.True;
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157 }
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158
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159 return IsExpressionResult.False;
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160 }
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161
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162 public override IBuildContext GetContext(Expression expression, int level, BuildInfo buildInfo)
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163 {
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164 throw new InvalidOperationException();
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165 }
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166 }
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167 }
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168 }
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