|
1 | | -# DynamiceExpressionBuilder |
2 | | -C# expression builder at run-time. |
| 1 | +## Overview |
| 2 | +Simple C# expression builder at run-time. |
| 3 | +Currently supports these operations: |
| 4 | +```csharp |
| 5 | +public enum Operation |
| 6 | + { |
| 7 | + Equals, |
| 8 | + NotEquals, |
| 9 | + GreaterThan, |
| 10 | + LessThan, |
| 11 | + GreaterThanOrEqual, |
| 12 | + LessThanOrEqual, |
| 13 | + Contains, |
| 14 | + ContainsWithToLower, |
| 15 | + StartsWith, |
| 16 | + EndsWith, |
| 17 | + StringEquals |
| 18 | + } |
| 19 | +``` |
| 20 | + |
| 21 | +## Implementation |
| 22 | +Steps: |
| 23 | ++ Build expression input list |
| 24 | +```csharp |
| 25 | +public static IList<ExpressionInput> GetExpressionInputList() |
| 26 | + { |
| 27 | + return new List<ExpressionInput> |
| 28 | + { |
| 29 | + new ExpressionInput |
| 30 | + { |
| 31 | + Operand = QueryOperand.And, //First Item does not matter And or OR |
| 32 | + Operation = Operation.Contains, |
| 33 | + PropertyName = "Name", |
| 34 | + Value = "Jack" |
| 35 | + }, |
| 36 | + new ExpressionInput |
| 37 | + { |
| 38 | + Operand = QueryOperand.And, |
| 39 | + Operation = Operation.StringEquals, //Operation.Equals |
| 40 | + PropertyName = "State", |
| 41 | + Value = "FL" |
| 42 | + }, |
| 43 | + new ExpressionInput |
| 44 | + { |
| 45 | + Operand = QueryOperand.Or, |
| 46 | + Operation = Operation.NotEquals, |
| 47 | + PropertyName = "CrimeRecord", |
| 48 | + Value = false |
| 49 | + }, |
| 50 | + new ExpressionInput |
| 51 | + { |
| 52 | + Operand = QueryOperand.And, |
| 53 | + Operation = Operation.GreaterThanOrEqual, |
| 54 | + PropertyName = "AnnualIncome", |
| 55 | + Value = (double)500000 //Value need to be parsed to Expression's object (T) type. Here T is of Citizen type and AnnualIncome is of double type. |
| 56 | + } |
| 57 | + }; |
| 58 | + } |
| 59 | +``` |
| 60 | ++ Passed to ExpressionBuilder |
| 61 | +```csharp |
| 62 | + var expressionList = ExpressionInputGenerator.GetExpressionInputList(); |
| 63 | + |
| 64 | + var expression = DynamicExpressionBuilder.ExpressionBuilder.GetExpression<Citizen>(expressionList); //Passing to expression builder. Here we are getting expression of Type Citizen |
| 65 | + Console.WriteLine($"Final Expression = {expression.ToString()}"); |
| 66 | +``` |
| 67 | +Output: `Final Expression = t => (((t.Name.Contains("Jack") AndAlso (Compare(t.State, "FL", OrdinalIgnoreCase) == 0)) Or (t.CrimeRecord != False)) AndAlso (t.AnnualIncome >= 500000))` |
| 68 | ++ Using Final expression |
| 69 | +```csharp |
| 70 | + var citizenRecords = CitizenRecordGenerator.GetCitizenRecordList(); |
| 71 | + var expression = DynamicExpressionBuilder.ExpressionBuilder.GetExpression<Citizen>(expressionList) |
| 72 | + |
| 73 | + var filterCitizens = citizenRecords.Where(expression.Compile()); //Expression Implementation |
| 74 | + Console.WriteLine($"\nFilter records: {filterCitizens.Count()}"); |
| 75 | +``` |
| 76 | + |
| 77 | +## Conclusion |
| 78 | + |
| 79 | +Above code are from example console app which is inside project. |
| 80 | + |
| 81 | + |
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