/// --------------------------------------------------------------------------------
/// <summary>
/// Returns whether the key exists within the collection. If the collection's
/// IDatabaseObjects.Subset has been set then only the subset is searched not the
/// entire table.
/// </summary>
///
/// <param name="objCollection">
/// The collection to search within.
/// </param>
///
/// <param name="objKey">
/// The key value to search by.
/// </param>
///
/// <returns><see cref="Boolean" /> (System.Boolean)</returns>
///
/// <example>
/// <code>
/// Public Function Exists(ByVal strProductCode As String) As Boolean
///
/// Return objDatabase.ObjectExists(Me, strProductCode)
///
/// End Function
/// </code>
/// </example>
/// --------------------------------------------------------------------------------
///
public bool ObjectExists(IDatabaseObjects objCollection, object objKey)
{
var objSelect = new SQL.SQLSelect();
string keyFieldName = objCollection.KeyFieldName();
EnsureKeyFieldNameIsSet(keyFieldName, objCollection);
objSelect.Tables.Add(objCollection.TableName());
//.Fields.Add objCollection.DistinctFieldName
objSelect.Where.Add(keyFieldName, SQL.ComparisonOperator.EqualTo, objKey);
var objSubset = objCollection.Subset();
if (objSubset != null && !objSubset.IsEmpty)
{
objSelect.Where.Add(objSubset);
}
using (ConnectionScope objConnection = new ConnectionScope(this))
using (IDataReader objReader = objConnection.Execute(objSelect))
return objReader.Read();
}
/// --------------------------------------------------------------------------------
/// <summary>
/// Returns an object from the collection using a unique key value.
/// The key must be unique within the collection. If the collection's
/// IDatabaseObjects.Subset has been implemented then the key need only be unique
/// within the subset specified, not the entire database table.
/// Returns Nothing/null if the object does exist with the specified key.
/// This feature is what differentiates Database.ObjectByKey() from Database.ObjectByKeyExists().
/// </summary>
///
/// <param name="objCollection">
/// The collection which contains the object.
/// </param>
///
/// <param name="objKey">
/// The key that identifies the object with the collection. The key is the value of
/// the field defined by the collection's IDatabaseObjects.KeyFieldName.
/// </param>
///
/// <returns><see cref="IDatabaseObject" /> (DatabaseObjects.IDatabaseObject)</returns>
///
/// <example>
/// <code>
/// Default Public ReadOnly Property Item(ByVal strProductCode As String) As Product
/// Get
///
/// Return objDatabase.ObjectByKey(Me, strProductCode)
///
/// End Get
/// End Property
/// </code>
/// </example>
/// --------------------------------------------------------------------------------
///
public IDatabaseObject ObjectByKeyIfExists(IDatabaseObjects objCollection, object objKey)
{
var objSelect = new SQL.SQLSelect();
string keyFieldName = objCollection.KeyFieldName();
EnsureKeyFieldNameIsSet(keyFieldName, objCollection);
SQL.SQLSelectTable objPrimaryTable = objSelect.Tables.Add(objCollection.TableName());
objSelect.Tables.Joins = objCollection.TableJoins(objPrimaryTable, objSelect.Tables);
objSelect.Where.Add(keyFieldName, SQL.ComparisonOperator.EqualTo, objKey);
var objSubset = objCollection.Subset();
if (objSubset != null && !objSubset.IsEmpty)
{
objSelect.Where.Add(objSubset);
}
using (ConnectionScope objConnection = new ConnectionScope(this))
{
using (IDataReader objReader = objConnection.Execute(objSelect))
{
if (objReader.Read())
return ObjectFromDataReader(objCollection, objReader);
else
return null;
}
}
}
private object ItemKeyFieldValue(IDatabaseObjects objCollection, IDatabaseObject objItem, SQL.SQLFieldValues objFieldValues)
{
//On the rare occurance that the KeyField is the same as the DistinctField
//then the key value may not have been set in the Save and therefore be
//available in the objFieldValues collection. In which case the
//key has to be extracted from the objItem.DistinctField.
object objKeyFieldValue;
if (string.Compare(objCollection.DistinctFieldName(), objCollection.KeyFieldName(), true) == 0)
objKeyFieldValue = objItem.DistinctValue;
else
objKeyFieldValue = objFieldValues[objCollection.KeyFieldName()].Value;
return objKeyFieldValue;
}
private IDictionary ObjectsDictionaryBase(IDatabaseObjects objCollection, bool bKeyIsDistinctField = false)
{
//Returns an IDictionary with the key being either the DistinctField or KeyField
IDictionary objDictionary = new Hashtable();
SQL.SQLSelect objSelect = new SQL.SQLSelect();
string strKeyField;
SQL.SQLSelectTable objPrimaryTable = objSelect.Tables.Add(objCollection.TableName());
objSelect.Tables.Joins = objCollection.TableJoins(objPrimaryTable, objSelect.Tables);
objSelect.Where = objCollection.Subset();
objSelect.OrderBy = objCollection.OrderBy();
using (ConnectionScope objConnection = new ConnectionScope(this))
{
using (IDataReader objReader = objConnection.Execute(objSelect))
{
if (bKeyIsDistinctField)
strKeyField = objCollection.DistinctFieldName();
else
strKeyField = objCollection.KeyFieldName();
while (objReader.Read())
objDictionary.Add(objReader[strKeyField], ObjectFromDataReader(objCollection, objReader));
return objDictionary;
}
}
}
private void ItemKeyEnsureValid(IDatabaseObjects objCollection, IDatabaseObject objItem, SQL.SQLFieldValues objFieldValues)
{
SQL.SQLSelect objSelect;
object objKeyFieldValue;
SQL.SQLConditions objSubset;
//If the key field is set and the key field is specified in the object
if (objCollection.KeyFieldName() != string.Empty && objFieldValues.Exists(objCollection.KeyFieldName()))
{
objKeyFieldValue = ItemKeyFieldValue(objCollection, objItem, objFieldValues);
if (objKeyFieldValue is string)
{
if (String.IsNullOrEmpty((string)objKeyFieldValue))
throw new Exceptions.DatabaseObjectsException(objItem.GetType().Name + " " + objCollection.KeyFieldName() + " field is Null");
}
objSelect = new SQL.SQLSelect();
objSelect.Tables.Add(objCollection.TableName());
objSelect.Fields.Add(objCollection.KeyFieldName());
objSelect.Where.Add(objCollection.KeyFieldName(), SQL.ComparisonOperator.EqualTo, objKeyFieldValue);
objSubset = objCollection.Subset();
if (objSubset != null && !objSubset.IsEmpty)
objSelect.Where.Add(objSubset);
if (objItem.IsSaved)
objSelect.Where.Add(objCollection.DistinctFieldName(), SQL.ComparisonOperator.NotEqualTo, objItem.DistinctValue);
using (ConnectionScope objConnection = new ConnectionScope(this))
using (IDataReader objReader = objConnection.Execute(objSelect))
if (objReader.Read())
throw new Exceptions.ObjectAlreadyExistsException(objItem, objKeyFieldValue);
}
}
