public static QueryPredicate CombinePredicatesWithOR(IList<QueryPredicate> filters)
{
if(filters == null || filters.Count == 0)
return null;
if(filters.Count == 1)
return filters[0];
var allParams = new List<ParameterExpression>();
var commonEntityParam = filters[0].Lambda.Parameters[0];
allParams.Add(commonEntityParam);
var rewriter = new FilterExpressionRewriter();
//Build new body and new parameter list
Expression newBody = null;
foreach(var filter in filters) {
var filterBody = rewriter.ReplaceParameter(filter.Lambda.Body, filter.Lambda.Parameters[0], commonEntityParam);
if(newBody == null)
newBody = filterBody;
else
newBody = Expression.Or(newBody, filterBody);
allParams.AddRange(filter.Lambda.Parameters.Skip(1)); //first param is entity
}
var newLambda = Expression.Lambda(newBody, allParams.ToArray());
var filterType = filters[0].GetType();
var result = (QueryPredicate) Activator.CreateInstance(filterType, newLambda);
return result;
}
public static QueryPredicate CombinePredicatesWithOR(IList <QueryPredicate> filters)
{
if (filters == null || filters.Count == 0)
{
return(null);
}
if (filters.Count == 1)
{
return(filters[0]);
}
var allParams = new List <ParameterExpression>();
var commonEntityParam = filters[0].Lambda.Parameters[0];
allParams.Add(commonEntityParam);
var rewriter = new FilterExpressionRewriter();
//Build new body and new parameter list
Expression newBody = null;
foreach (var filter in filters)
{
var filterBody = rewriter.ReplaceParameter(filter.Lambda.Body, filter.Lambda.Parameters[0], commonEntityParam);
if (newBody == null)
{
newBody = filterBody;
}
else
{
newBody = Expression.Or(newBody, filterBody);
}
allParams.AddRange(filter.Lambda.Parameters.Skip(1)); //first param is entity
}
var newLambda = Expression.Lambda(newBody, allParams.ToArray());
var filterType = filters[0].GetType();
var result = (QueryPredicate)Activator.CreateInstance(filterType, newLambda);
return(result);
}