Data Subscriptions: Creation and Updating API Overview

Subscription creation is accessible through DocumentStore's Subscriptions Property, of type DocumentSubscriptions:

string Create(SubscriptionCreationOptions options, string database = null);
string Create<T>(Expression<Func<T, bool>> predicate = null, 
                 SubscriptionCreationOptions options = null, string database = null);
string Create<T>(SubscriptionCreationOptions<T> options, string database = null);

Task<string> CreateAsync(SubscriptionCreationOptions options,
                         string database = null,
                         CancellationToken token = default);

Task<string> CreateAsync<T>(Expression<Func<T, bool>> predicate = null,
                            SubscriptionCreationOptions options = null,
                            string database = null,
                            CancellationToken token = default);

Task<string> CreateAsync<T>(SubscriptionCreationOptions<T> options,
                            string database = null,
                            CancellationToken token = default);

Non generic version of the class, relies on user's full knowledge of the RQL query structure

An RQL statement will be built based on the fields.

public class SubscriptionCreationOptions<T>
{
    public string Name { get; set; }
    public Expression<Func<T, bool>> Filter { get; set; }
    public Expression<Func<T, object>> Projection { get; set; }
    public Action<ISubscriptionIncludeBuilder<T>> Includes { get; set; }
    public string ChangeVector { get; set; }
    public string MentorNode { get; set; }
}

Modifies an existing data subscription. These methods are accessible at DocumentStore.Subscriptions.

string Update(SubscriptionUpdateOptions options, string database = null);

Task<string> UpdateAsync(SubscriptionUpdateOptions options, string database = null, 
                    CancellationToken token = default);

Inherits from SubscriptionCreationOptions and has all the same fields (see above) plus the two additional fields described below:

public class SubscriptionUpdateOptions : SubscriptionCreationOptions
{
    public long? Id { get; set; }
    public bool CreateNew { get; set; }
}

All subscriptions, are eventually translated to an RQL-like statement. These statements has four parts:

• Functions definition part, like in ordinary RQL. Those functions can contain any JavaScript code, and also supports load and include operations.

• From statement, defining the documents source, ex: from Orders. The from statement can only address collections, therefore, indexes are not supported.

• Where statement describing the criteria according to which it will be decided to either send the documents to the worker or not. Those statements supports either RQL like equality operations (=, ==) ,
  plain JavaScript expressions or declared function calls, allowing to perform complex filtering logic.
  The subscriptions RQL does not support any of the known RQL searching keywords.

• Select statement, that defines the projection to be performed. The select statements can contain function calls, allowing complex transformations.

• Include statement allowing to define include path in document.

from Orders as o
where o.Lines[].Product = "products/1-A"

declare function filterLines(doc, productId)
{
    if (!!doc.Lines){
        return doc.Lines.filter(x=>x.Product == productId).length >0;
    }
    return false;
}

from Orders as o
where filterLines(o, "products/1-A")