/// <summary>
/// Method that generate filter string ends with comparison expression
/// </summary>
/// <param name="memberExp">Member expression</param>
/// <param name="filterProperty">KeyValuePair for properties and values</param>
/// <param name="property">Property that will be filtered</param>
/// <returns>Expression for the filter string ends with comparison</returns>
internal static Expression GenerateStringEndsWithExpression(
Expression memberExp,
ConstantExpression tokenExp
)
{
return(Expression.Call(memberExp, ReflectionsHelper.GetMethodFromType(memberExp.Type, "EndsWith", 1, 0, new List <Type> {
typeof(string)
}), tokenExp));
}
/// <summary>
/// Method that generate filter string contains comparison expression
/// </summary>
/// <param name="memberExp">Member expression</param>
/// <param name="filterProperty">KeyValuePair for properties and values</param>
/// <param name="property">Property that will be filtered</param>
/// <returns>Expression for the filter string contains comparison</returns>
internal static Expression GenerateStringContainsExpression(
Expression memberExp,
ConstantExpression tokenExp
)
{
var method = ReflectionsHelper.GetMethodFromType(memberExp.Type, "Contains", 1, 0, new List <Type> {
typeof(string)
});
return(Expression.Call(memberExp, method, tokenExp));
}
/// <summary>
/// Method that generates a lambda expression for search criteria
/// </summary>
/// <typeparam name="TSource">Expression type attribute</typeparam>
/// <param name="searchableProperties">List of searchable properties</param>
/// <param name="terms">List of terms to search</param>
/// <param name="queryStrict">parameter that indicates when all terms should be contained in the property</param>
/// <returns>Lambda expression for the search</returns>
internal static Expression <Func <TSource, bool> > GenerateSearchCriteriaExpression <TSource>(
IList <string> searchableProperties,
IList <string> terms,
bool queryStrict)
where TSource : class
{
List <Expression> orExpressions = new List <Expression>();
var xExp = Expression.Parameter(typeof(TSource), "x");
foreach (var propertyInfo in typeof(TSource).GetProperties().Where(x =>
searchableProperties.Any(y => y.ToLower().Equals(x.Name.ToLower())) &&
!CriteriasHelper.GetNonQueryableTypes().Any(type => type == x.PropertyType)
).ToList())
{
Expression memberExp = Expression.MakeMemberAccess(xExp, propertyInfo);
Expression memberHasValue = null;
if (memberExp.Type != typeof(string))
{
if (Nullable.GetUnderlyingType(memberExp.Type) != null)
{
memberHasValue = Expression.MakeMemberAccess(memberExp, memberExp.Type.GetProperty("HasValue"));
memberHasValue = queryStrict ? memberHasValue : Expression.Not(memberHasValue);
}
else if (memberExp.Type.IsClass)
{
memberHasValue = Expression.Equal(memberExp, Expression.Constant(null));
memberHasValue = !queryStrict ? memberHasValue : Expression.Not(memberHasValue);
}
memberExp = Expression.Call(memberExp, ReflectionsHelper.GetMethodFromType(memberExp.Type, "ToString", 0, 0));
}
else
{
memberHasValue = Expression.Equal(memberExp, Expression.Constant(null));
memberHasValue = !queryStrict ? memberHasValue : Expression.Not(memberHasValue);
}
memberExp = Expression.Call(memberExp, ReflectionsHelper.GetMethodFromType(memberExp.Type, "ToLower", 0, 0));
List <Expression> andExpressions = new List <Expression>();
foreach (var token in terms)
{
andExpressions.Add(ExpressionsHelper.GenerateStringContainsExpression(memberExp, Expression.Constant(token, typeof(string))));
}
orExpressions.Add(queryStrict ? ExpressionsHelper.GenerateAndExpressions(andExpressions) : ExpressionsHelper.GenerateOrExpression(andExpressions));
}
Expression orExp = ExpressionsHelper.GenerateOrExpression(orExpressions);
return(Expression.Lambda <Func <TSource, bool> >(orExp.Reduce(), xExp));
}