public static DbExpression Convert(DynamicFilterDefinition filter, DbExpressionBinding binding, ObjectContext objectContext)
{
var visitor = new LambdaToDbExpressionVisitor(filter, binding, objectContext);
var expression = visitor.Visit(filter.Predicate) as LambdaExpression;
return(visitor.GetDbExpressionForExpression(expression.Body));
}
private DbFilterExpression BuildFilterExpressionWithDynamicFilters(string entityName, IEnumerable <DynamicFilterDefinition> filterList, DbExpressionBinding binding, DbExpression predicate)
{
if (!filterList.Any())
{
return(null);
}
var edmType = binding.VariableType.EdmType as EntityType;
if (edmType == null)
{
return(null);
}
List <DbExpression> conditionList = new List <DbExpression>();
HashSet <string> processedFilterNames = new HashSet <string>();
foreach (var filter in filterList)
{
if (processedFilterNames.Contains(filter.FilterName))
{
continue; // Already processed this filter - attribute was probably inherited in a base class
}
processedFilterNames.Add(filter.FilterName);
DbExpression dbExpression;
if (!string.IsNullOrEmpty(filter.ColumnName))
{
// Single column equality filter
// Need to map through the EdmType properties to find the actual database/cspace name for the entity property.
// It may be different from the entity property!
var edmProp = edmType.Properties.Where(p => p.MetadataProperties.Any(m => m.Name == "PreferredName" && m.Value.Equals(filter.ColumnName))).FirstOrDefault();
if (edmProp == null)
{
continue; // ???
}
// database column name is now in edmProp.Name. Use that instead of filter.ColumnName
var columnProperty = DbExpressionBuilder.Property(DbExpressionBuilder.Variable(binding.VariableType, binding.VariableName), edmProp.Name);
var param = columnProperty.Property.TypeUsage.Parameter(filter.CreateDynamicFilterName(filter.ColumnName));
dbExpression = DbExpressionBuilder.Equal(columnProperty, param);
}
else if (filter.Predicate != null)
{
// Lambda expression filter
dbExpression = LambdaToDbExpressionVisitor.Convert(filter, binding, _ObjectContext);
}
else
{
throw new System.ArgumentException(string.Format("Filter {0} does not contain a ColumnName or a Predicate!", filter.FilterName));
}
// Create an expression to check to see if the filter has been disabled and include that check with the rest of the filter expression.
// When this parameter is null, the filter is enabled. It will be set to true (in DynamicFilterExtensions.GetFilterParameterValue) if
// the filter has been disabled.
var boolPrimitiveType = LambdaToDbExpressionVisitor.TypeUsageForPrimitiveType(typeof(bool?), _ObjectContext);
var isDisabledParam = boolPrimitiveType.Parameter(filter.CreateFilterDisabledParameterName());
conditionList.Add(DbExpressionBuilder.Or(dbExpression, DbExpressionBuilder.Not(DbExpressionBuilder.IsNull(isDisabledParam))));
}
int numConditions = conditionList.Count;
DbExpression newPredicate;
switch (numConditions)
{
case 0:
return(null);
case 1:
newPredicate = conditionList.First();
break;
default:
// Have multiple conditions. Need to append them together using 'and' conditions.
newPredicate = conditionList.First();
for (int i = 1; i < numConditions; i++)
{
newPredicate = newPredicate.And(conditionList[i]);
}
break;
}
// 'and' the existing Predicate if there is one
if (predicate != null)
{
newPredicate = newPredicate.And(predicate);
}
return(DbExpressionBuilder.Filter(binding, newPredicate));
}
