/// <summary>
/// Write a DeletedRecord in deleteIn dataset for the specified key
/// instead of actually deleting the record. This ensures that
/// a record in another dataset does not become visible during
/// lookup in a sequence of datasets.
///
/// To avoid an additional roundtrip to the data store, the delete
/// marker is written even when the record does not exist.
/// </summary>
public override void Delete <TKey, TRecord>(TypedKey <TKey, TRecord> key, TemporalId deleteIn)
{
// Error message if data source is readonly or has CutoffTime set
CheckNotReadOnly(deleteIn);
// For pinned records, delete in root dataset irrespective of the value of saveTo
if (IsPinned <TRecord>())
{
deleteIn = TemporalId.Empty;
}
// Create DeletedRecord with the specified key
var record = new DeletedRecord {
Key = key.Value
};
// Get collection
var collection = GetOrCreateCollection <TRecord>();
// This method guarantees that TemporalIds will be in strictly increasing
// order for this instance of the data source class always, and across
// all processes and machine if they are not created within the same
// second.
var recordId = CreateOrderedTemporalId();
record.Id = recordId;
// Assign dataset and then initialize, as the results of
// initialization may depend on record.DataSet
record.DataSet = deleteIn;
// By design, insert will fail if TemporalId is not unique within the collection
collection.BaseCollection.InsertOne(record);
}
/// <summary>
/// Write a DeletedRecord for the dataset of the context and the specified
/// key instead of actually deleting the record. This ensures that
/// a record in another dataset does not become visible during
/// lookup in a sequence of datasets.
///
/// To avoid an additional roundtrip to the data store, the delete
/// marker is written even when the record does not exist.
/// </summary>
public static void Delete <TKey, TRecord>(this Context obj, TypedKey <TKey, TRecord> key)
where TKey : TypedKey <TKey, TRecord>, new()
where TRecord : TypedRecord <TKey, TRecord>
{
// Delete in the dataset of the context
obj.DataSource.Delete(key, obj.DataSet);
}
/// <summary>
/// Load record by string key from the specified dataset or
/// its list of imports. The lookup occurs first in descending
/// order of dataset TemporalIds, and then in the descending
/// order of record TemporalIds within the first dataset that
/// has at least one record. Both dataset and record TemporalIds
/// are ordered chronologically to one second resolution,
/// and are unique within the database server or cluster.
///
/// The root dataset has empty TemporalId value that is less
/// than any other TemporalId value. Accordingly, the root
/// dataset is the last one in the lookup order of datasets.
///
/// The first record in this lookup order is returned, or null
/// if no records are found or if DeletedRecord is the first
/// record.
///
/// Return null if there is no record for the specified TemporalId;
/// however an exception will be thrown if the record exists but
/// is not derived from TRecord.
/// </summary>
public override TRecord LoadOrNull <TKey, TRecord>(TypedKey <TKey, TRecord> key, TemporalId loadFrom)
{
// For pinned records, load from root dataset irrespective of the value of loadFrom
if (IsPinned <TRecord>())
{
loadFrom = TemporalId.Empty;
}
// String value of the key in semicolon delimited format for use in the query
string keyValue = key.ToString();
// Look for exact match of the key
var baseQueryable = GetOrCreateCollection <TRecord>()
.BaseCollection
.AsQueryable()
.Where(p => p.Key == keyValue);
// Apply constraints on dataset and revision time
var queryableWithFinalConstraints = ApplyFinalConstraints(baseQueryable, loadFrom);
// Order by dataset and then by ID in descending order
var orderedQueryable = queryableWithFinalConstraints
.OrderByDescending(p => p.DataSet)
.OrderByDescending(p => p.Id);
// Result will be null if the record is not found
var baseResult = orderedQueryable.FirstOrDefault();
// Check not only for null but also for the DeletedRecord
if (baseResult != null && !baseResult.Is <DeletedRecord>())
{
// Record is found but we do not yet know if it has the right type.
// Attempt to cast Record to TRecord and check if the result is null.
TRecord result = baseResult.As <TRecord>();
if (result == null)
{
// If cast result is null, the record was found but it is an instance
// of class that is not derived from TRecord, in this case the API
// requires error message, not returning null
throw new Exception(
$"Stored type {result.GetType().Name} for Key={key.Value} in " +
$"DataSet={loadFrom} is not an instance of the requested type {typeof(TRecord).Name}.");
}
// Initialize before returning
result.Init(Context);
return(result);
}
else
{
// Record not found or is a DeletedRecord, return null
return(null);
}
}
/// <summary>
/// Load record from context.DataSource, overriding the dataset
/// specified in the context with the value specified as the
/// second parameter. The lookup occurs in the specified dataset
/// and its imports, expanded to arbitrary depth with repetitions
/// and cyclic references removed.
///
/// IMPORTANT - this overload of the method loads from loadFrom
/// dataset, not from context.DataSet.
///
/// If Record property is set, its value is returned without
/// performing lookup in the data store; otherwise the record
/// is loaded from storage and cached in Record and the
/// cached value is returned from subsequent calls.
///
/// Once the record has been cached, the same version will be
/// returned in subsequent calls with the same key instance.
/// Create a new key or call earRecord() method to force
/// reloading new version of the record from storage.
///
/// Error message if the record is not found or is a DeletedRecord.
/// </summary>
public static TRecord Load <TKey, TRecord>(this DataSource obj, TypedKey <TKey, TRecord> key, TemporalId loadFrom)
where TKey : TypedKey <TKey, TRecord>, new()
where TRecord : TypedRecord <TKey, TRecord>
{
// This method will return null if the record is
// not found or the found record is a DeletedRecord
var result = obj.LoadOrNull(key, loadFrom);
// Error message if null, otherwise return
if (result == null)
{
throw new Exception(
$"Record with key {key} is not found in dataset with TemporalId={loadFrom}.");
}
return(result);
}
/// <summary>
/// Write a DeletedRecord in deleteIn dataset for the specified key
/// instead of actually deleting the record. This ensures that
/// a record in another dataset does not become visible during
/// lookup in a sequence of datasets.
///
/// To avoid an additional roundtrip to the data store, the delete
/// marker is written even when the record does not exist.
/// </summary>
public abstract void Delete <TKey, TRecord>(TypedKey <TKey, TRecord> key, TemporalId deleteIn)
where TKey : TypedKey <TKey, TRecord>, new()
where TRecord : TypedRecord <TKey, TRecord>;
/// <summary>
/// Load record by string key from the specified dataset or
/// its list of imports. The lookup occurs first in descending
/// order of dataset TemporalIds, and then in the descending
/// order of record TemporalIds within the first dataset that
/// has at least one record. Both dataset and record TemporalIds
/// are ordered chronologically to one second resolution,
/// and are unique within the database server or cluster.
///
/// The root dataset has empty TemporalId value that is less
/// than any other TemporalId value. Accordingly, the root
/// dataset is the last one in the lookup order of datasets.
///
/// The first record in this lookup order is returned, or null
/// if no records are found or if DeletedRecord is the first
/// record.
///
/// Return null if there is no record for the specified TemporalId;
/// however an exception will be thrown if the record exists but
/// is not derived from TRecord.
/// </summary>
public abstract TRecord LoadOrNull <TKey, TRecord>(TypedKey <TKey, TRecord> key, TemporalId loadFrom)
where TKey : TypedKey <TKey, TRecord>, new()
where TRecord : TypedRecord <TKey, TRecord>;
/// <summary>
/// Write a DeletedRecord in deleteIn dataset for the specified key
/// instead of actually deleting the record. This ensures that
/// a record in another dataset does not become visible during
/// lookup in a sequence of datasets.
///
/// To avoid an additional roundtrip to the data store, the delete
/// marker is written even when the record does not exist.
/// </summary>
public static void Delete <TKey, TRecord>(this Context obj, TypedKey <TKey, TRecord> key, TemporalId deleteIn)
where TKey : TypedKey <TKey, TRecord>, new()
where TRecord : TypedRecord <TKey, TRecord>
{
obj.DataSource.Delete(key, deleteIn);
}
/// <summary>
/// Load record by string key from the specified dataset or
/// its list of imports. The lookup occurs first in descending
/// order of dataset TemporalIds, and then in the descending
/// order of record TemporalIds within the first dataset that
/// has at least one record. Both dataset and record TemporalIds
/// are ordered chronologically to one second resolution,
/// and are unique within the database server or cluster.
///
/// The root dataset has empty TemporalId value that is less
/// than any other TemporalId value. Accordingly, the root
/// dataset is the last one in the lookup order of datasets.
///
/// The first record in this lookup order is returned, or null
/// if no records are found or if DeletedRecord is the first
/// record.
///
/// Return null if there is no record for the specified TemporalId;
/// however an exception will be thrown if the record exists but
/// is not derived from TRecord.
/// </summary>
public static TRecord LoadOrNull <TKey, TRecord>(this Context obj, TypedKey <TKey, TRecord> key, TemporalId loadFrom)
where TKey : TypedKey <TKey, TRecord>, new()
where TRecord : TypedRecord <TKey, TRecord>
{
return(obj.DataSource.LoadOrNull(key, loadFrom));
}
/// <summary>
/// Load record from context.DataSource, overriding the dataset
/// specified in the context with the value specified as the
/// second parameter. The lookup occurs in the specified dataset
/// and its imports, expanded to arbitrary depth with repetitions
/// and cyclic references removed.
///
/// This overload of the method loads from from context.DataSet.
///
/// If Record property is set, its value is returned without
/// performing lookup in the data store; otherwise the record
/// is loaded from storage and cached in Record and the
/// cached value is returned from subsequent calls.
///
/// Once the record has been cached, the same version will be
/// returned in subsequent calls with the same key instance.
/// Create a new key or call earRecord() method to force
/// reloading new version of the record from storage.
///
/// Error message if the record is not found or is a DeletedRecord.
/// </summary>
public static TRecord Load <TKey, TRecord>(this Context obj, TypedKey <TKey, TRecord> key)
where TKey : TypedKey <TKey, TRecord>, new()
where TRecord : TypedRecord <TKey, TRecord>
{
return(obj.DataSource.Load(key, obj.DataSet));
}
/// <summary>
/// Load record by string key from the specified dataset or
/// its list of imports. The lookup occurs first in descending
/// order of dataset TemporalIds, and then in the descending
/// order of record TemporalIds within the first dataset that
/// has at least one record. Both dataset and record TemporalIds
/// are ordered chronologically to one second resolution,
/// and are unique within the database server or cluster.
///
/// The root dataset has empty TemporalId value that is less
/// than any other TemporalId value. Accordingly, the root
/// dataset is the last one in the lookup order of datasets.
///
/// The first record in this lookup order is returned, or null
/// if no records are found or if DeletedRecord is the first
/// record.
///
/// Return null if there is no record for the specified TemporalId;
/// however an exception will be thrown if the record exists but
/// is not derived from TRecord.
/// </summary>
public override TRecord LoadOrNull <TKey, TRecord>(TypedKey <TKey, TRecord> key, TemporalId loadFrom)
{
throw MethodCalledForNullDataSourceError();
}
/// <summary>
/// Write a DeletedRecord in deleteIn dataset for the specified key
/// instead of actually deleting the record. This ensures that
/// a record in another dataset does not become visible during
/// lookup in a sequence of datasets.
///
/// To avoid an additional roundtrip to the data store, the delete
/// marker is written even when the record does not exist.
/// </summary>
public override void Delete <TKey, TRecord>(TypedKey <TKey, TRecord> key, TemporalId deleteIn)
{
throw MethodCalledForNullDataSourceError();
}
