/// <summary>
/// Execute a query and return its results.
/// </summary>
/// <typeparam name="T">
/// The type of element returned by the query.
/// </typeparam>
/// <param name="query">
/// The query to evaluate and get the results for.
/// </param>
/// <returns>
/// Results of the query.
/// </returns>
internal async Task <IEnumerable <T> > Execute <T>(MobileServiceTableQuery <T> query)
{
// Compile the query from the underlying IQueryable's expression
// tree
MobileServiceTableQueryDescription compiledQuery = this.Compile(query);
// Send the query
string odata = compiledQuery.ToQueryString();
JToken response = await query.Table.ReadAsync(odata, query.Parameters);
// Parse the results
long totalCount;
JArray values = this.GetResponseSequence(response, out totalCount);
return(new TotalCountEnumerable <T>(
totalCount,
query.Table.MobileServiceClient.Serializer.Deserialize(values, compiledQuery.ProjectionArgumentType).Select(
value =>
{
// Apply the projection to the instance transforming it
// as desired
foreach (Delegate projection in compiledQuery.Projections)
{
value = projection.DynamicInvoke(value);
}
return (T)value;
})));
}
/// <summary>
/// Initializes a new instance of the MobileServiceTableQueryTranslator
/// class.
/// </summary>
/// <param name="query">
/// The <see cref="T:MobileServiceTableQuery`1{T}"/> which
/// is being translated.
/// </param>
internal MobileServiceTableQueryTranslator(MobileServiceTableQuery <T> query)
{
Debug.Assert(query != null);
this.query = query;
this.queryDescription = new MobileServiceTableQueryDescription(query.Table.TableName, query.RequestTotalCount);
}
/// <summary>
/// Compile the query into a MobileServiceTableQueryDescription.
/// </summary>
/// <returns>
/// The compiled OData query.
/// </returns>
internal MobileServiceTableQueryDescription Compile <T>(MobileServiceTableQuery <T> query)
{
// Compile the query from the underlying IQueryable's expression
// tree
MobileServiceTableQueryTranslator <T> translator = new MobileServiceTableQueryTranslator <T>(query);
MobileServiceTableQueryDescription compiledQuery = translator.Translate();
return(compiledQuery);
}
/// <summary>
/// Initializes a new instance of the MobileServiceCollectionView
/// class.
/// </summary>
/// <param name="table">
/// Table associated with the data source's query.
/// </param>
/// <param name="query">The query the data source represents.</param>
internal MobileServiceCollectionView(MobileServiceTable <T> table, MobileServiceTableQueryDescription query)
{
Debug.Assert(table != null, "table cannot be null!");
Debug.Assert(query != null, "query cannot be null!");
this.table = table;
this.query = query;
// Evaluate the query immediately and start loading the data for it
this.data = new List <T>();
this.EvaluateQueryAsync();
}
/// <summary>
/// Compile the query into a MobileServiceTableQueryDescription.
/// </summary>
/// <returns>The compiled OData query.</returns>
internal MobileServiceTableQueryDescription Compile()
{
// Compile the query from the underlying IQueryable's expression
// tree
MobileServiceTableQueryDescription compiledQuery = MobileServiceTableQueryTranslator.Translate(this.Query.Expression);
// Forward along the request for the total count
compiledQuery.IncludeTotalCount = this.RequestTotalCount;
// Associate the current table with the compiled query
if (string.IsNullOrEmpty(compiledQuery.TableName))
{
SerializableType type = SerializableType.Get(
compiledQuery.ProjectionArgumentType ?? typeof(T));
compiledQuery.TableName = type.TableName;
}
return(compiledQuery);
}
/// <summary>
/// Evaluate a query and return its results.
/// </summary>
/// <typeparam name="U">
/// The type of element returned by the query.
/// </typeparam>
/// <param name="table">
/// Access to MobileServices table operations.
/// </param>
/// <param name="query">
/// The description of the query to evaluate and get the results for.
/// </param>
/// <returns>Results of the query.</returns>
internal static Task <IEnumerable <U> > EvaluateQueryAsync <U>(IMobileServiceTable <T> table, MobileServiceTableQueryDescription query)
{
Debug.Assert(query != null, "query cannot be null!");
Debug.Assert(table != null, "table cannot be null!");
// Send the query
string odata = query.ToString();
return(table.ReadAsync(odata, query.Parameters).ContinueWith(t =>
{
// Parse the results
long totalCount;
JsonArray values = MobileServiceTable <T> .GetResponseSequence(t.Result, out totalCount);
return (IEnumerable <U>) new TotalCountEnumerable <U>(
totalCount,
values.Select(
item =>
{
// Create and fill a new instance of the type we should
// deserialize (which is either T or the input param
// to the projection that will modify T).
object obj = Activator.CreateInstance(query.ProjectionArgumentType ?? typeof(U));
MobileServiceTableSerializer.Deserialize(item, obj);
// Apply the projection to the instance transforming it
// as desired
if (query.Projection != null)
{
obj = query.Projection.DynamicInvoke(obj);
}
return (U)obj;
}));
}));
}
/// <summary>
/// Create a new collection view based on the query.
/// </summary>
/// <returns>The collection view.</returns>
public MobileServiceCollectionView <T> ToCollectionView()
{
MobileServiceTableQueryDescription query = this.Compile();
return(new MobileServiceCollectionView <T>(this.Table, query));
}
