public Expression <Func <TEntity, bool> > GetFilterExpression(IFilterDto filterDto)
{
Expression propertyExp, someValue, containsMethodExp, combinedExp;
Expression <Func <TEntity, bool> > exp = c => true, oldExp;
MethodInfo method;
var parameterExp = Expression.Parameter(typeof(TEntity), "type");
foreach (PropertyInfo propertyInfo in filterDto.GetType().GetProperties())
{
if (propertyInfo.GetValue(filterDto, null) != null)
{
oldExp = exp;
propertyExp = Expression.Property(parameterExp, propertyInfo.Name);
method = typeof(object).GetMethod("Equals", new[] { typeof(object) });
someValue = Expression.Constant(filterDto.GetType().GetProperty(propertyInfo.Name).GetValue(filterDto, null), typeof(object));
containsMethodExp = Expression.Call(propertyExp, method, someValue);
exp = Expression.Lambda <Func <TEntity, bool> >(containsMethodExp, parameterExp);
combinedExp = Expression.AndAlso(exp.Body, oldExp.Body);
exp = Expression.Lambda <Func <TEntity, bool> >(combinedExp, exp.Parameters[0]);
}
}
return(exp);
}
public static Expression <Func <TEntity, bool> > GetFilterExpression <TEntity>(this IFilterDto filterDto)
{
Expression propertyExp, propertyValue, combinedExp;
Expression <Func <TEntity, bool> > exp = c => true, oldExp;
var parameterExp = Expression.Parameter(typeof(TEntity), "type");
foreach (PropertyInfo propertyInfo in filterDto.GetType().GetProperties())
{
if (propertyInfo.GetValue(filterDto, null) != null)
{
oldExp = exp;
var targetProperty = propertyInfo.GetCustomAttributes <FilterAttribute>(true).ToList()[0].TargetProperty;
propertyExp = Expression.Property(parameterExp, targetProperty);
propertyValue = Expression.Constant(filterDto.GetType().GetProperty(propertyInfo.Name).GetValue(filterDto));
Expression condition = SetConditionType(propertyInfo, propertyExp, propertyValue);
exp = Expression.Lambda <Func <TEntity, bool> >(condition, parameterExp);
combinedExp = Expression.AndAlso(exp.Body, oldExp.Body);
exp = Expression.Lambda <Func <TEntity, bool> >(combinedExp, exp.Parameters[0]);
}
}
return(exp);
}
