/// <summary>
/// In case of a delete command we always filter based on the tenantId
/// </summary>
private static void InterceptDeleteCommand(DbCommandTreeInterceptionContext interceptionContext, string userId)
{
var deleteCommand = interceptionContext.Result as DbDeleteCommandTree;
if (deleteCommand != null)
{
var column = TenantAwareAttribute.GetTenantColumnName(deleteCommand.Target.VariableType.EdmType);
if (!string.IsNullOrEmpty(column))
{
// Create the variable reference in order to create the property
var variableReference = DbExpressionBuilder.Variable(deleteCommand.Target.VariableType,
deleteCommand.Target.VariableName);
// Create the property to which will assign the correct value
var tenantProperty = DbExpressionBuilder.Property(variableReference, column);
var tenantIdWherePredicate = DbExpressionBuilder.Equal(tenantProperty, DbExpression.FromString(userId));
// The initial predicate is the sql where statement
var initialPredicate = deleteCommand.Predicate;
// Add to the initial statement the tenantId statement which translates in sql AND TenantId = 'value'
var finalPredicate = initialPredicate.And(tenantIdWherePredicate);
var newDeleteCommand = new DbDeleteCommandTree(
deleteCommand.MetadataWorkspace,
deleteCommand.DataSpace,
deleteCommand.Target,
finalPredicate);
interceptionContext.Result = newDeleteCommand;
}
}
}
/// <summary>
/// This method called before the one below it when a filtering is already exists in the query (e.g. fetch an entity by id)
/// so we apply the dynamic filtering at this level
/// </summary>
public override DbExpression Visit(DbFilterExpression expression)
{
var column = TenantAwareAttribute.GetTenantColumnName(expression.Input.Variable.ResultType.EdmType);
if (!_injectedDynamicFilter && !string.IsNullOrEmpty(column))
{
var newFilterExpression = BuildFilterExpression(expression.Input, expression.Predicate, column);
if (newFilterExpression != null)
{
// If not null, a new DbFilterExpression has been created with our dynamic filters.
return(base.Visit(newFilterExpression));
}
}
return(base.Visit(expression));
}
/// <summary>
/// In case of an update command we always filter based on the tenantId
/// </summary>
private static bool InterceptUpdate(DbCommandTreeInterceptionContext interceptionContext, string userId)
{
var updateCommand = interceptionContext.Result as DbUpdateCommandTree;
if (updateCommand != null)
{
var column = TenantAwareAttribute.GetTenantColumnName(updateCommand.Target.VariableType.EdmType);
if (!string.IsNullOrEmpty(column))
{
// Create the variable reference in order to create the property
var variableReference = DbExpressionBuilder.Variable(updateCommand.Target.VariableType,
updateCommand.Target.VariableName);
// Create the property to which will assign the correct value
var tenantProperty = DbExpressionBuilder.Property(variableReference, column);
// Create the tenantId where predicate, object representation of sql where tenantId = value statement
var tenantIdWherePredicate = DbExpressionBuilder.Equal(tenantProperty, DbExpression.FromString(userId));
// Remove potential assignment of tenantId for extra safety
var filteredSetClauses =
updateCommand.SetClauses.Cast <DbSetClause>()
.Where(sc => ((DbPropertyExpression)sc.Property).Property.Name != column);
// Construct the final clauses, object representation of sql insert command values
var finalSetClauses =
new ReadOnlyCollection <DbModificationClause>(new List <DbModificationClause>(filteredSetClauses));
// The initial predicate is the sql where statement
var initialPredicate = updateCommand.Predicate;
// Add to the initial statement the tenantId statement which translates in sql AND TenantId = 'value'
var finalPredicate = initialPredicate.And(tenantIdWherePredicate);
var newUpdateCommand = new DbUpdateCommandTree(
updateCommand.MetadataWorkspace,
updateCommand.DataSpace,
updateCommand.Target,
finalPredicate,
finalSetClauses,
updateCommand.Returning);
interceptionContext.Result = newUpdateCommand;
// True means an interception successfully happened so there is no need to continue
return(true);
}
}
return(false);
}
public override DbExpression Visit(DbScanExpression expression)
{
var column = TenantAwareAttribute.GetTenantColumnName(expression.Target.ElementType);
if (!_injectedDynamicFilter && !string.IsNullOrEmpty(column))
{
// Get the current expression
var dbExpression = base.Visit(expression);
// Get the current expression binding
var currentExpressionBinding = DbExpressionBuilder.Bind(dbExpression);
var newFilterExpression = BuildFilterExpression(currentExpressionBinding, null, column);
if (newFilterExpression != null)
{
// If not null, a new DbFilterExpression has been created with our dynamic filters.
return(base.Visit(newFilterExpression));
}
}
return(base.Visit(expression));
}
