/// <summary>
/// Filters a query based upon the predicate provided.
/// </summary>
/// <typeparam name="TSource">The type of ParseObject being queried for.</typeparam>
/// <param name="source">The base <see cref="ParseQuery{TSource}"/> to which
/// the predicate will be added.</param>
/// <param name="predicate">A function to test each ParseObject for a condition.
/// The predicate must be able to be represented by one of the standard Where
/// functions on ParseQuery</param>
/// <returns>A new ParseQuery whose results will match the given predicate as
/// well as the source's filters.</returns>
public static ParseQuery <TSource> Where <TSource>(
this ParseQuery <TSource> source, Expression <Func <TSource, bool> > predicate)
where TSource : ParseObject
{
// Handle top-level logic operators && and ||
var binaryExpression = predicate.Body as BinaryExpression;
if (binaryExpression != null)
{
if (binaryExpression.NodeType == ExpressionType.AndAlso)
{
return(source
.Where(Expression.Lambda <Func <TSource, bool> >(
binaryExpression.Left, predicate.Parameters))
.Where(Expression.Lambda <Func <TSource, bool> >(
binaryExpression.Right, predicate.Parameters)));
}
if (binaryExpression.NodeType == ExpressionType.OrElse)
{
var left = source.Where(Expression.Lambda <Func <TSource, bool> >(
binaryExpression.Left, predicate.Parameters));
var right = source.Where(Expression.Lambda <Func <TSource, bool> >(
binaryExpression.Right, predicate.Parameters));
return(left.Or(right));
}
}
var normalized = new WhereNormalizer().Visit(predicate.Body);
var methodCallExpr = normalized as MethodCallExpression;
if (methodCallExpr != null)
{
return(source.WhereMethodCall(predicate, methodCallExpr));
}
var binaryExpr = normalized as BinaryExpression;
if (binaryExpr != null)
{
return(source.WhereBinaryExpression(predicate, binaryExpr));
}
var unaryExpr = normalized as UnaryExpression;
if (unaryExpr != null && unaryExpr.NodeType == ExpressionType.Not)
{
var node = unaryExpr.Operand as MethodCallExpression;
if (IsParseObjectGet(node) && (node.Type == typeof(bool) || node.Type == typeof(bool?)))
{
// This is a raw boolean field access like 'where !obj.Get<bool>("foo")'
return(source.WhereNotEqualTo(GetValue(node.Arguments[0]) as string, true));
}
}
throw new InvalidOperationException(
"Encountered an unsupported expression for ParseQueries.");
}