private static Expression <Func <TDbType, bool> > BuildInnerPredicate <TDbType>(IPredicateParser predicateParser, PropertyInfo searchField, MemberInfo dbFieldMemberInfo)
{
var dbType = typeof(TDbType);
// Create an "x" as TDbType
var dbTypeParameter = Expression.Parameter(dbType, @"x");
// Get at x.firstName
var dbFieldMember = Expression.MakeMemberAccess(dbTypeParameter, dbFieldMemberInfo);
Expression <Func <TDbType, bool> > predicateInner = null;
foreach (var predicateItem in predicateParser.Items)
{
var predicateItemSingle = predicateItem as PredicateItemSingle;
var predicateItemRange = predicateItem as PredicateItemRange;
if (predicateItemSingle != null)
{
// Create the MethodCallExpression like x.firstName.Contains(criterion)
if (searchField.PropertyType == typeof(string))
{
var str = predicateItemSingle.Value as string ?? "";
var startsWithAsterisk = str.StartsWith("*");
var endsWithAsterisk = str.EndsWith("*");
str = str.Trim('*').Trim();
MethodCallExpression callExpression;
if (startsWithAsterisk && !endsWithAsterisk)
{
callExpression = Expression.Call(dbFieldMember, StringEndsWithMethod, new Expression[] { Expression.Constant(str) });
}
else if (!startsWithAsterisk && endsWithAsterisk)
{
callExpression = Expression.Call(dbFieldMember, StringStartsWithMethod, new Expression[] { Expression.Constant(str) });
}
else
{
callExpression = Expression.Call(dbFieldMember, StringContainsMethod, new Expression[] { Expression.Constant(str) });
}
predicateInner = (predicateInner ?? PredicateBuilder.New <TDbType>(false)).Or(Expression.Lambda(callExpression, dbTypeParameter) as Expression <Func <TDbType, bool> >);
}
else
{
if (dbFieldMember.Type.IsEnum)
{
if (!dbFieldMember.Type.IsEnumDefined(predicateItemSingle.Value))
{
continue;
}
var enumValue = (int)predicateItemSingle.Value;
if (enumValue <= 0)
{
continue;
}
var enumObj = Enum.ToObject(dbFieldMember.Type, (int)predicateItemSingle.Value);
predicateInner = (predicateInner ?? PredicateBuilder.New <TDbType>(false)).Or(Expression.Lambda <Func <TDbType, bool> >(Expression.Equal(dbFieldMember, Expression.Constant(enumObj)), new[] { dbTypeParameter }));
}
else
{
predicateInner = (predicateInner ?? PredicateBuilder.New <TDbType>(false)).Or(Expression.Lambda <Func <TDbType, bool> >(Expression.Equal(dbFieldMember, Expression.Constant(predicateItemSingle.Value)), new[] { dbTypeParameter }));
}
}
}
else if (predicateItemRange != null)
{
var predicateRange = PredicateBuilder.New <TDbType>(true);
predicateRange = predicateRange.And(Expression.Lambda <Func <TDbType, bool> >(Expression.GreaterThanOrEqual(dbFieldMember, Expression.Constant(predicateItemRange.Value1)), new[] { dbTypeParameter }));
predicateRange = predicateRange.And(Expression.Lambda <Func <TDbType, bool> >(Expression.LessThanOrEqual(dbFieldMember, Expression.Constant(predicateItemRange.Value2)), new[] { dbTypeParameter }));
predicateInner = (predicateInner ?? PredicateBuilder.New <TDbType>(false)).Or(predicateRange);
}
}
return(predicateInner);
}
//private static readonly MethodInfo BooleanEqualsMethod = typeof(bool).GetMethod(@"Equals", BindingFlags.Instance | BindingFlags.Public, null, new[] { typeof(bool) }, null);
/// <summary>
/// Build a predicate with linq clauses, taking searchCriteria object's properties to define where conditions.
/// </summary>
/// <typeparam name="TDbType">Type of entity to build predicate for</typeparam>
/// <param name="searchCriteria">Object which contains criteria for predicate</param>
/// <param name="predicateParser">Implementation of predicate parser that will parse predicates as string</param>
/// <param name="includeNullValues">Determines whether null values are included when constructing query</param>
/// <returns></returns>
public static Expression <Func <TDbType, bool> > BuildPredicate <TDbType>(object searchCriteria, IPredicateParser predicateParser, bool includeNullValues)
{
var filterDictionary = searchCriteria.ToFilterDictionary(includeNullValues);
return(BuildPredicate <TDbType>(filterDictionary, predicateParser));
}
public static Expression <Func <TDbType, bool> > BuildPredicate <TDbType>(Dictionary <string, string> searchCriteria, IPredicateParser predicateParser)
{
var predicateOuter = PredicateBuilder.New <TDbType>(true);
var predicateErrorFields = new List <string>();
var dict = searchCriteria; // as Dictionary<string, string>;
if (dict == null || !dict.Any())
{
return(predicateOuter);
}
var searchFields = typeof(TDbType).GetProperties();
foreach (var searchField in searchFields)
{
// Get the name of the DB field, which may not be the same as the property name.
var dbFieldName = GetDbFieldName(searchField);
var dbType = typeof(TDbType);
var dbFieldMemberInfo = dbType.GetMember(dbFieldName, BindingFlags.IgnoreCase | BindingFlags.Public | BindingFlags.Instance).SingleOrDefault();
if (dbFieldMemberInfo == null || !dict.ContainsKey(dbFieldMemberInfo.Name))
{
continue;
}
var predicateValue = dict[dbFieldMemberInfo.Name];
if (predicateValue == null)
{
continue;
}
var rangesAllowed = searchField.PropertyType != typeof(string);
if (!predicateParser.Parse(predicateValue, rangesAllowed, searchField.PropertyType))
{
predicateErrorFields.Add(dbFieldMemberInfo.Name);
continue;
}
if (!predicateParser.Items.Any())
{
continue;
}
var predicateInner = BuildInnerPredicate <TDbType>(predicateParser, searchField, dbFieldMemberInfo);
if (predicateInner == null)
{
continue;
}
predicateOuter = predicateOuter.And(predicateInner);
}
return(predicateOuter);
}
public NotebookService(IPredicateParser predicateParser, IDataAccess context)
{
this._predicateParser = predicateParser;
this._context = context;
}