98 lines
3.9 KiB
C#
98 lines
3.9 KiB
C#
using System;
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using System.Linq;
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using System.Linq.Expressions;
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namespace WX.CRM.Common
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{
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public static class QueryHelper
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{
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public static IQueryable<T> Filter<T>(this IQueryable<T> queryable, Expression<Func<T, bool>> expression)
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{
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expression = ValidateExpression(expression);
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if (expression == null) return queryable;
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return queryable.Where(expression);
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}
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public static Expression<Func<T, bool>> ValidateExpression<T>(Expression<Func<T, bool>> expression)
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{
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CheckNull<T>(expression, "expression");
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if (GetCriteriaCount(expression) > 1)
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throw new InvalidOperationException(String.Format("仅允许添加一个条件，条件：{0}", expression));
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object value = GetValue(expression);
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if (value == null)
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return null;
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if (string.IsNullOrWhiteSpace(value.ToString()))
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return null;
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return expression;
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}
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public static int GetCriteriaCount(LambdaExpression expression)
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{
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if (expression == null)
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return 0;
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string result = expression.ToString().Replace("AndAlso", "|").Replace("OrElse", "|");
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return result.Split('|').Count();
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}
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public static object GetValue(LambdaExpression expression)
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{
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if (expression == null)
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return null;
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Expression getexpression = GetBinaryExpression(expression);
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BinaryExpression binaryExpression = getexpression as BinaryExpression;
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if (binaryExpression != null)
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return GetBinaryValue(binaryExpression);
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MethodCallExpression callExpression = getexpression as MethodCallExpression;
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if (callExpression != null)
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return GetMethodValue(callExpression);
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return null;
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}
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private static Expression GetBinaryExpression(LambdaExpression expression)
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{
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var binaryExpression = expression.Body as BinaryExpression;
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if (binaryExpression != null)
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return binaryExpression;
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var unaryExpression = expression.Body as UnaryExpression;
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if (unaryExpression != null)
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{
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var OperandBinary = unaryExpression.Operand as BinaryExpression;
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if (OperandBinary != null)
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return OperandBinary;
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var OperandMethod = unaryExpression.Operand as MethodCallExpression;
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if (OperandMethod != null)
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return OperandMethod;
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}
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MethodCallExpression callExpression = expression.Body as MethodCallExpression;
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if (callExpression != null)
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{
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return callExpression;
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}
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return null;
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}
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private static object GetBinaryValue(BinaryExpression binaryExpression)
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{
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var unaryExpression = binaryExpression.Right as UnaryExpression;
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if (unaryExpression != null)
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return GetConstantValue(unaryExpression.Operand);
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return GetConstantValue(binaryExpression.Right);
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}
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private static object GetConstantValue(Expression expression)
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{
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var constantExpression = expression as ConstantExpression;
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if (constantExpression != null)
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return constantExpression.Value;
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return null;
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}
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private static object GetMethodValue(MethodCallExpression callExpression)
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{
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var argumentExpression = callExpression.Arguments.FirstOrDefault();
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return GetConstantValue(argumentExpression);
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}
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public static void CheckNull<T>(Expression<Func<T, bool>> expression, string paraName)
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{
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if (expression == null)
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throw new ArgumentException(paraName);
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}
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}
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}
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