/// <summary>
/// Returns a list of distinct column values that can be used for select filters.
/// </summary>
/// <param name="column">The column.</param>
public virtual IList <string> GetDistinctColumnValues(DataTablesColumn <TEntity, TEntityViewModel> column)
{
var parameterExp = ExpressionHelper.BuildParameterExpression <TEntity>();
var propertyExp = ExpressionHelper.BuildPropertyExpression(parameterExp, column.PrivatePropertyName);
var stringExp = Expression.Call(propertyExp, ExpressionHelper.Object_ToString);
var lambda = Expression.Lambda <Func <TEntity, string> >(stringExp, parameterExp);
return(GetDistinctColumnValues(lambda));
}
protected List <Expression <Func <TEntity, bool> > > BuildWhereExpression <TEntity>(IViewModel viewModel, IList <string> where)
{
//将条件按照列组合起来
Dictionary <UiColumnInfo, List <Condition> > dictConditions = new Dictionary <UiColumnInfo, List <Condition> >();
foreach (var filter in where)
{
var ss = filter.Split(' ');
if (ss.Length != 3)
{
continue;
}
var columnInfo = viewModel.GetColumnInfo(ss[0]);
var condition = new Condition()
{
Key = ss[1], Value = ss[2]
};
if (columnInfo != null)
{
if (dictConditions.ContainsKey(columnInfo))
{
List <Condition> conditions = dictConditions[columnInfo];
conditions.Add(condition);
}
else
{
List <Condition> conditions = new List <Condition>();
conditions.Add(condition);
dictConditions[columnInfo] = conditions;
}
}
}
List <Expression <Func <TEntity, bool> > > expressions = new List <Expression <Func <TEntity, bool> > >();
foreach (var columnCondition in dictConditions)
{
ParameterExpression parameterExpression = ExpressionHelper.BuildParameterExpression(typeof(TEntity));
UiColumnInfo columnInfo = columnCondition.Key;
Expression <Func <TEntity, bool> > prediateExpression = BuildColumnConditionExpression(parameterExpression, typeof(TEntity), columnInfo, columnCondition.Value)
as Expression <Func <TEntity, bool> >;
if (prediateExpression != null)
{
expressions.Add(prediateExpression);
}
}
return(expressions);
}