/// <summary>
/// Gets a batch of changes to synchronize when given batch size,
/// destination knowledge, and change data retriever parameters.
/// </summary>
/// <returns>A DbSyncContext object that will be used to retrieve the modified data.</returns>
public virtual (SyncContext, BatchInfo) GetSnapshot(
SyncContext context, SyncSet schema, string batchDirectory,
CancellationToken cancellationToken, IProgress <ProgressArgs> progress = null)
{
var sb = new StringBuilder();
var underscore = "";
if (context.Parameters != null)
{
foreach (var p in context.Parameters.OrderBy(p => p.Name))
{
var cleanValue = new string(p.Value.ToString().Where(char.IsLetterOrDigit).ToArray());
var cleanName = new string(p.Name.Where(char.IsLetterOrDigit).ToArray());
sb.Append($"{underscore}{cleanName}_{cleanValue}");
underscore = "_";
}
}
var directoryName = sb.ToString();
directoryName = string.IsNullOrEmpty(directoryName) ? "ALL" : directoryName;
var directoryFullPath = Path.Combine(batchDirectory, directoryName);
// if no snapshot present, just return null value.
if (!Directory.Exists(directoryFullPath))
{
return(context, null);
}
// Serialize on disk.
var jsonConverter = new JsonConverter <BatchInfo>();
var summaryFileName = Path.Combine(directoryFullPath, "summary.json");
BatchInfo batchInfo = null;
// Create the schema changeset
var changesSet = new SyncSet(schema.ScopeName);
// Create a Schema set without readonly columns, attached to memory changes
foreach (var table in schema.Tables)
{
DbSyncAdapter.CreateChangesTable(schema.Tables[table.TableName, table.SchemaName], changesSet);
}
using (var fs = new FileStream(summaryFileName, FileMode.Open, FileAccess.Read))
{
batchInfo = jsonConverter.Deserialize(fs);
}
batchInfo.SetSchema(changesSet);
return(context, batchInfo);
}