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));
}
public static DbExpression Convert(DynamicFilterDefinition filter, DbExpressionBinding binding, DbContext dbContext, DataSpace dataSpace)
{
var visitor = new LambdaToDbExpressionVisitor(filter, binding, dbContext, dataSpace);
var expression = visitor.Visit(filter.Predicate) as LambdaExpression;
var dbExpression = visitor.GetDbExpressionForExpression(expression.Body);
if (dbExpression is DbPropertyExpression)
{
// Special case to handle a condition that is just a plain "boolFlag" or a nullable generic condition.
// For a nullable type, we only get here when the filter has either not specified a value for the nullable
// parameter or it has specified "null" - both evaluate the same as far as the method prototypes can tell
// since the method signature is "param = null". This needs to generate a sql "is null" condition.
// Otherwise, no param value was specified so we are assuming that we need to generate a "positive"
// condition. i.e. the filter just said "b.prop" which generally means "b.prop == true".
// To generate that condition correctly for all types (may not necessarily be a bool), we create a condition
// like "!(b.prop == [defaultValue])"
if (IsNullableType(expression.Body.Type))
{
dbExpression = DbExpressionBuilder.IsNull(dbExpression);
}
else
{
var defaultValue = DbExpressionBuilder.Constant(dbExpression.ResultType, Activator.CreateInstance(expression.Body.Type));
dbExpression = DbExpressionBuilder.Not(DbExpressionBuilder.Equal(dbExpression, defaultValue));
}
}
return(dbExpression);
}
public static DbExpression Convert(DynamicFilterDefinition filter, DbExpressionBinding binding, DbContext dbContext, DataSpace dataSpace)
{
var visitor = new LambdaToDbExpressionVisitor(filter, binding, dbContext, dataSpace);
var expression = visitor.Visit(filter.Predicate) as LambdaExpression;
var dbExpression = visitor.GetDbExpressionForExpression(expression.Body);
if (dbExpression is DbPropertyExpression)
{
// Special case to handle a condition that is just a plan "boolFlag" condition.
// In order for the sql to generate correct, we need to turn this into "boolFlag = true"
// Figuring out the defaultValue like this should produce the default (0, false, empty) value for the type
// we are working with. So checking then generating a condition of "not (@var = defaultValue)" should produce
// the correct condition.
var defaultValue = DbExpressionBuilder.Constant(dbExpression.ResultType, Activator.CreateInstance(expression.Body.Type));
dbExpression = DbExpressionBuilder.Not(DbExpressionBuilder.Equal(dbExpression, defaultValue));
}
return(dbExpression);
}
private Expression MapAnyOrAllExpression(MethodCallExpression node)
{
if (_DataSpace != DataSpace.CSpace)
{
throw new ApplicationException("Filters on child collections are only supported when using CSpace");
}
if ((node.Arguments == null) || (node.Arguments.Count > 2))
{
throw new ApplicationException("Any function call has more than 2 arguments");
}
// Visit the first argument so that we can get the DbPropertyExpression which is the source of the method call.
var sourceExpression = Visit(node.Arguments[0]);
var collectionExpression = GetDbExpressionForExpression(sourceExpression);
// Visit this DbExpression using the QueryVisitor in case it has it's own filters that need to be applied.
var queryVisitor = new DynamicFilterQueryVisitorCSpace(_DbContext);
collectionExpression = collectionExpression.Accept(queryVisitor);
DbExpression dbExpression;
if (node.Arguments.Count == 2)
{
// The method call has a predicate that needs to be evaluated. This must be done against the source
// argument - not the current binding.
var binding = collectionExpression.Bind();
// Visit the lambda expression against this binding (which will evaluate all of the
// conditions in the expression against this binding and for this filter).
var lambdaExpression = node.Arguments[1] as LambdaExpression;
var visitor = new LambdaToDbExpressionVisitor(_Filter, binding, _DbContext, _DataSpace);
var subExpression = visitor.Visit(lambdaExpression) as LambdaExpression;
var subDbExpression = visitor.GetDbExpressionForExpression(subExpression.Body);
// Create an "Any" or "All" DbExpression from the results
if (node.Method.Name == "All")
{
dbExpression = DbExpressionBuilder.All(binding, subDbExpression);
}
else
{
dbExpression = DbExpressionBuilder.Any(binding, subDbExpression);
}
}
else
{
// This should not even be possible - linq/IEnumerable does not have such a method!
if (node.Method.Name == "All")
{
throw new ApplicationException("All() with no parameters is not supported");
}
// No predicate so just create an Any DbExpression against the collection expression
dbExpression = DbExpressionBuilder.Any(collectionExpression);
}
MapExpressionToDbExpression(node, dbExpression);
return(node);
}
