private static Exp CreateSubExpression(Exp pe, Type type, string text, FullTextSearchOptions options, bool isQueriable = false)
{
var texts = text.Split(new string[] { "||" }, StringSplitOptions.RemoveEmptyEntries)
.Select(t => t.Trim().ToLower())
.Where(t => t.Length > 0)
.ToList();
var properties = type.GetProperties().AsEnumerable();
if (isQueriable)
{
properties = properties.GetMappedProperties();
}
Exp predicateBody = null;
foreach (var prop in properties)
{
//Check if we can use this property in Search
if (options == null || options.Filter == null || options.Filter.Invoke(prop))
{
var paramExp = Exp.Property(pe, prop);
if (prop.PropertyType == typeof(string) || prop.PropertyType == typeof(int) ||
prop.PropertyType == typeof(int?))
{
Exp notNullExp = null;
if (prop.PropertyType == typeof(string))
{
Exp nullConst = Exp.Constant(null, typeof(string));
notNullExp = Exp.NotEqual(paramExp, nullConst);
}
Exp toStringExp = paramExp;
//Check if property has int type
if (prop.PropertyType == typeof(int?) || prop.PropertyType == typeof(int))
{
if (!isQueriable)
{
Exp toNullableIntExp = null;
//property should be nullable
if (prop.PropertyType == typeof(int))
{
toNullableIntExp = Exp.TypeAs(paramExp, typeof(int?));
}
Exp valueExp = null;
if (toNullableIntExp != null)
{
notNullExp = Exp.Property(toNullableIntExp, "HasValue");
valueExp = Exp.Property(toNullableIntExp, "Value");
}
else
{
notNullExp = Exp.Property(paramExp, "HasValue");
valueExp = Exp.Property(paramExp, "Value");
}
notNullExp = Exp.Equal(notNullExp, Exp.Constant(true, typeof(bool)));
var convertToString = typeof(Convert).GetMethod("ToString", new[] { typeof(int) });
toStringExp = Exp.Call(convertToString, valueExp);
}
else
{
var convertToString = typeof(Convert).GetMethod("ToString", new[] { typeof(int) });
toStringExp = Exp.Call(convertToString, Exp.Convert(paramExp, typeof(int)));
}
}
Exp peLower = Exp.Call(toStringExp, typeof(string).GetMethod("ToLower", System.Type.EmptyTypes));
Exp conditionExp = null;
foreach (var txt in texts)
{
var constant = Exp.Constant(txt, typeof(string));
Exp containsExp = Exp.Call(peLower, typeof(string).GetMethod("Contains", new[] { typeof(string) }), constant);
if (conditionExp != null)
{
conditionExp = Exp.OrElse(conditionExp, containsExp);
}
else
{
conditionExp = containsExp;
}
}
Exp andExp = (notNullExp != null) ? Exp.AndAlso(notNullExp, conditionExp) : conditionExp;
if (predicateBody != null)
{
predicateBody = Exp.OrElse(predicateBody, andExp);
}
else
{
predicateBody = andExp;
}
}
//If this property is't simple and the depth > 0
if (options != null && options.Depth != 0 &&
!prop.PropertyType.IsSimpleType() && !prop.PropertyType.IsEnumerable())
{
options.Depth -= 1;
var subExp = CreateSubExpression(paramExp, prop.PropertyType, text, options, isQueriable);
options.Depth += 1;
if (subExp != null)
{
Exp notNullExp = Exp.NotEqual(paramExp, Exp.Constant(null, typeof(object)));
subExp = Exp.AndAlso(notNullExp, subExp);
predicateBody = (predicateBody != null) ? Exp.OrElse(predicateBody, subExp) : subExp;
}
}
}
}
return(predicateBody);
}
/// <summary>
/// Filters a sequence of values based on a fulltext search predicate
/// </summary>
/// <typeparam name="T">Any type</typeparam>
/// <param name="source">The source - some IQueryable object.</param>
/// <param name="text">The text - meaning of the search</param>
/// <param name="options">The options for full-text search</param>
/// <returns></returns>
public static IQueryable <T> FullTextSearchQuery <T>(this IQueryable <T> source, string text, FullTextSearchOptions options = null)
{
var pe = Exp.Parameter(typeof(T), "d");
var predicateBody = CreateSubExpression(pe, typeof(T), text, options, isQueriable: true);
if (predicateBody != null)
{
var whereExp = Exp.Lambda <Func <T, bool> >(predicateBody, new ParameterExpression[] { pe });
source = source.Where(whereExp);
}
//Order by Expression
if (options == null)
{
return(source);
}
var orderByProperty = options.OrderBy;
if (string.IsNullOrEmpty(orderByProperty))
{
orderByProperty = typeof(T).GetProperties().First().Name;
}
var property = Exp.Property(pe, orderByProperty);
var lambda = Exp.Lambda(property, pe);
var method = options.IsDescendingOrder ? "OrderByDescending" : "OrderBy";
var orderByExp = Exp.Call(typeof(Queryable), method, new[] { typeof(T), property.Type }, source.Expression, lambda);
source = source.Provider.CreateQuery <T>(orderByExp) as IOrderedQueryable <T>;
return(source);
}