/// <inheritdoc/>
public override FieldMiddleware CreateExecutor <TEntityType>()
{
return(next => context => ExecuteAsync(next, context));
async ValueTask ExecuteAsync(
FieldDelegate next,
IMiddlewareContext context)
{
// first we let the pipeline run and produce a result.
await next(context).ConfigureAwait(false);
if (context.Result is not null)
{
var visitorContext =
new MongoDbProjectionVisitorContext(context, context.ObjectType);
var visitor = new ProjectionVisitor <MongoDbProjectionVisitorContext>();
visitor.Visit(visitorContext);
if (!visitorContext.TryCreateQuery(
out MongoDbProjectionDefinition? projections) ||
visitorContext.Errors.Count > 0)
{
context.Result = Array.Empty <TEntityType>();
foreach (IError error in visitorContext.Errors)
{
context.ReportError(error.WithPath(context.Path));
}
}
else
{
context.LocalContextData =
context.LocalContextData.SetItem(
nameof(ProjectionDefinition <TEntityType>),
projections);
await next(context).ConfigureAwait(false);
if (context.Result is IMongoDbExecutable executable)
{
context.Result = executable.WithProjection(projections);
}
}
}
}
public async IAsyncEnumerator <T> GetAsyncEnumerator(CancellationToken cancellation = default)
{
var query = (DataServiceQuery) new DataServiceContext(account.TableEndpoint).CreateQuery <T>(tableName)
.Provider.CreateQuery(expression);
// OData will translate the enum value in a filter to TYPENAME.'ENUMVALUE'.
// The type name can contain the + sign if it's a nested type, too. So we
// need to remove the type name plus the dot and just leave the string
// value as part of the filter string.
var rawqs = Regex.Replace(
query.RequestUri.GetComponents(UriComponents.Query, UriFormat.Unescaped),
"(\\W)[\\w\\+\\.]+('\\w+')", "$1$2");
// We need to count & break manually because $top is interpreted as the max records per page
// if the set matches more items. This is clearly unintuitive and *not* what one typically
// wants when using LINQ queries! See Note on https://docs.microsoft.com/en-us/rest/api/storageservices/querying-tables-and-entities#supported-query-options
var qs = HttpUtility.ParseQueryString(rawqs);
if (!long.TryParse(qs["$top"], out var top))
{
top = -1;
}
long count = 0;
// Covers weird case of top == 0.
if (count == top)
{
yield break;
}
if (qs["$select"] != null)
{
// Collect the properties being projected, and append the built-in ones to them.
var projection = new ProjectionVisitor();
projection.Visit(expression);
if (projection.Properties.Count > 0)
{
qs["$select"] = string.Join(",", projection.Properties
// NOTE: skip key properties since they are renamed back before deserialization below
.Where(prop => prop != partitionKeyProperty && prop != rowKeyProperty)
// NOTE: always project the built-in props.
.Concat(new[]
{
nameof(ITableEntity.PartitionKey),
nameof(ITableEntity.RowKey),
nameof(ITableEntity.ETag),
nameof(ITableEntity.Timestamp)
}));
}
}
var filter = qs["$filter"];
if (filter != null && (partitionKeyProperty != null || rowKeyProperty != null))
{
if (partitionKeyProperty != null)
{
filter = Regex.Replace(filter, partitionKeyProperty + "(\\W)", "PartitionKey$1");
}
if (rowKeyProperty != null)
{
filter = Regex.Replace(filter, rowKeyProperty + "(\\W)", "RowKey$1");
}
qs["$filter"] = filter;
}
if (PartitionKey != null)
{
if (filter == null)
{
filter = "PartitionKey eq '" + PartitionKey + "'";
}
else
{
filter = "PartitionKey eq '" + PartitionKey + "' and " + filter;
}
qs["$filter"] = filter;
}
var builder = new UriBuilder(query.RequestUri)
{
Query = string.Join("&", qs.AllKeys.Select(x => $"{x}={qs[x]}"))
};
var request = new HttpRequestMessage(HttpMethod.Get, builder.Uri)
.AddAuthorizationHeader(account);
var response = await Http.Client.SendAsync(request);
while (true)
{
response.EnsureSuccessStatusCode();
var json = await response.Content.ReadAsStringAsync();
var doc = JsonDocument.Parse(json);
foreach (var element in doc.RootElement.GetProperty("value").EnumerateArray())
{
var mem = new MemoryStream();
var writer = new Utf8JsonWriter(mem);
writer.WriteStartObject();
// Write the renamed key properties, if any.
if (partitionKeyProperty != null)
{
writer.WriteString(partitionKeyProperty, element.GetProperty("PartitionKey").GetString());
}
if (rowKeyProperty != null)
{
writer.WriteString(rowKeyProperty, element.GetProperty("RowKey").GetString());
}
foreach (var property in element.EnumerateObject())
{
property.WriteTo(writer);
}
writer.WriteEndObject();
writer.Flush();
var data = Encoding.UTF8.GetString(mem.ToArray());
var item = serializer.Deserialize <T>(data);
if (item != null)
{
yield return(item);
count++;
if (count == top)
{
yield break;
}
}
}
if (!response.Headers.TryGetValues("x-ms-continuation-NextPartitionKey", out var nextPartitionKeyValues) ||
nextPartitionKeyValues.FirstOrDefault() is not string nextPartitionKey ||
string.IsNullOrEmpty(nextPartitionKey) ||
!response.Headers.TryGetValues("x-ms-continuation-NextRowKey", out var nextRowKeyValues) ||
nextRowKeyValues.FirstOrDefault() is not string nextRowKey ||
string.IsNullOrEmpty(nextRowKey))
{
break;
}
qs["NextPartitionKey"] = nextPartitionKey;
qs["NextRowKey"] = nextRowKey;
builder.Query = string.Join("&", qs.AllKeys.Select(x => $"{x}={qs[x]}"));
request = new HttpRequestMessage(HttpMethod.Get, builder.Uri)
.AddAuthorizationHeader(account);
response = await Http.Client.SendAsync(request);
}
}
public override IEnumerable <Projection <TValue> > Accept <TValue>(ProjectionVisitor <TValue> visitor, ProjectionVisitor <TValue> .Arguments args, GraphDirection direction) => visitor.Visit(this, args, direction);