csharp-sdk-upm/Storage/Source/Internal/Operation/IAVFieldOperation.cs

43 lines
2.1 KiB
C#

namespace LeanCloud.Storage.Internal {
/// <summary>
/// A AVFieldOperation represents a modification to a value in a AVObject.
/// For example, setting, deleting, or incrementing a value are all different kinds of
/// AVFieldOperations. AVFieldOperations themselves can be considered to be
/// immutable.
/// </summary>
public interface IAVFieldOperation {
/// <summary>
/// Converts the AVFieldOperation to a data structure that can be converted to JSON and sent to
/// LeanCloud as part of a save operation.
/// </summary>
/// <returns>An object to be JSONified.</returns>
object Encode();
/// <summary>
/// Returns a field operation that is composed of a previous operation followed by
/// this operation. This will not mutate either operation. However, it may return
/// <code>this</code> if the current operation is not affected by previous changes.
/// For example:
/// {increment by 2}.MergeWithPrevious({set to 5}) -> {set to 7}
/// {set to 5}.MergeWithPrevious({increment by 2}) -> {set to 5}
/// {add "foo"}.MergeWithPrevious({delete}) -> {set to ["foo"]}
/// {delete}.MergeWithPrevious({add "foo"}) -> {delete} /// </summary>
/// <param name="previous">The most recent operation on the field, or null if none.</param>
/// <returns>A new AVFieldOperation or this.</returns>
IAVFieldOperation MergeWithPrevious(IAVFieldOperation previous);
/// <summary>
/// Returns a new estimated value based on a previous value and this operation. This
/// value is not intended to be sent to LeanCloud, but it is used locally on the client to
/// inspect the most likely current value for a field.
///
/// The key and object are used solely for AVRelation to be able to construct objects
/// that refer back to their parents.
/// </summary>
/// <param name="oldValue">The previous value for the field.</param>
/// <param name="key">The key that this value is for.</param>
/// <returns>The new value for the field.</returns>
object Apply(object oldValue, string key);
}
}