/// <summary>
/// While creating a media entity, we could only post with its binary media resource.
/// If we want to add values to its non-media properties, we need to to update/patch the entity
/// instance with those property values.
/// </summary>
/// <returns></returns>
private async Task UpdateNonMediaProperty(IODataEntity entity, string value)
{
string keyProeprtyName = "pk";
string propertyName = "title";
// We do not update the key property. Only remains those proeprties to be updated.
entity.Properties.Remove(keyProeprtyName);
var prop = new ODataProperty(propertyName);
prop.Value = value;
entity.Properties[propertyName] = prop;
var req = new ODataRequestParametersSingle(entity.EditResourcePath, RequestMode.Update, entity);
req.Etag = entity.Etag;
try
{
var exec = Store.ScheduleRequest(req);
await exec.Response;
}
catch (Exception ex)
{
result.Text += ex.Message + "\n";
}
}
private async Task showEntityAsync()
{
if (storeOperator != null)
{
IODataEntity entity = await storeOperator.QueryTheLastEntity();
if (entity != null)
{
var resp = await storeOperator.GetStreamFromEntity(entity);
MemoryStream ms = new MemoryStream();
resp.InputStream.CopyTo(ms);
var stream = ms.AsRandomAccessStream();
stream.Seek(0);
var image = new BitmapImage();
image.SetSource(stream);
this.ImageBox.Source = image;
}
else
{
this.ImageBox.Source = null;
}
}
}
/// <summary>
/// Get the last entity
/// </summary>
/// <returns></returns>
public async Task <IODataEntity> QueryTheLastEntity()
{
IODataEntity ent = null;
int count = await QueryEntityCount("Photos");
result.Text += string.Format("Total Count: {0}", count) + "\n";
StringBuilder builder = new StringBuilder();
IODataResponse response = await QueryOfflineStore("Photos");
IODataEntitySet entitySet = (IODataEntitySet)((IODataResponseSingle)response).Payload;
foreach (IODataEntity entity in entitySet)
{
ent = entity;
}
// Display the title of the current entity.
if (ent != null)
{
string propertyName = "title";
string propertyValue = (string)ent.Properties[propertyName].Value;
result.Text += string.Format("Property {0} = {1}", propertyName, propertyValue) + "\n";
}
return(ent);
}
private async void Delete_ClickAsync(object sender, RoutedEventArgs e)
{
if (storeOperator != null)
{
IODataEntity entity = await storeOperator.QueryTheLastEntity();
if (entity != null)
{
await storeOperator.DeleteStreamEntity(entity);
await showEntityAsync();
}
}
}
public async Task <IODataDownloadMediaResource> GetStreamFromEntity(IODataEntity mediaEntity)
{
IODataMediaRequestExecution exec;
try
{
exec = Store.ScheduleReadMediaResource(mediaEntity.MediaLink);
return(await exec.Response);
} catch (Exception ex)
{
result.Text += ex.Message + "\n";
return(null);
}
}
public async Task <bool> DeleteStreamEntity(IODataEntity mediaEntity)
{
ODataRequestParametersSingle req;
IODataResponse resp;
IODataRequestExecution exec;
req = new ODataRequestParametersSingle(mediaEntity.EditResourcePath, RequestMode.Delete, mediaEntity);
try
{
exec = Store.ScheduleRequest(req);
resp = await exec.Response;
return(true);
}
catch (Exception ex)
{
result.Text += ex.Message + "\n";
return(false);
}
}
public async Task <bool> UpdateStreamEntity(IODataEntity mediaEntity)
{
var stream = await pickAPicture();
if (stream == null)
{
return(false);
}
Windows.Storage.Streams.Buffer buffer = new Windows.Storage.Streams.Buffer((uint)stream.Size);
await stream.ReadAsync(buffer, (uint)stream.Size, InputStreamOptions.None);
DataReader dataReader = DataReader.FromBuffer(buffer);
byte[] bytes = new byte[buffer.Length];
dataReader.ReadBytes(bytes);
ODataRequestParametersSingle req;
IODataResponse resp;
IODataRequestExecution exec;
req = new ODataRequestParametersSingle(mediaEntity.EditMediaLink.ToString(), RequestMode.Update, new ODataUploadMediaResource(bytes, stream.ContentType));
req.Etag = mediaEntity.MediaEtag;
try
{
exec = Store.ScheduleRequest(req);
resp = await exec.Response;
await UpdateNonMediaProperty(mediaEntity, "Updated at: " + DateTime.Now.ToString());
return(true);
}
catch (Exception ex)
{
result.Text += ex.Message + "\n";
return(false);
}
}
