/// <summary>
/// 根据传入的值，创建一个 NpgsqlParameter 对象，并装入属性 Parameters 中
/// </summary>
/// <param name="val">参数的值</param>
/// <param name="type">运算符类型</param>
/// <param name="specificType">数据库指定列的类型</param>
protected void SetValue(object val, ExpressionType type, Type specificType = null)
{
if (val == null)
{
CommandText.Remove(CommandText.Length - 3, 3);
if (type == ExpressionType.Equal)
{
CommandText.Append(" IS NULL");
}
else if (type == ExpressionType.NotEqual)
{
CommandText.Append(" IS NOT NULL");
}
}
else
{
string p_key = Guid.NewGuid().ToString("N");
NpgsqlParameter parameter = null;
if (specificType != null)
{
parameter = new NpgsqlParameter(p_key, NpgsqlDbType.Enum);
parameter.SpecificType = specificType;
parameter.Value = val;
}
else
{
parameter = new NpgsqlParameter(p_key, val);
}
Parameters.Add(parameter);
CommandText.Append($"@{p_key}");
}
}
/// <summary>
/// 根据传入的值，创建一个 NpgsqlParameter 对象，并装入属性 Parameters 中
/// </summary>
/// <param name="val">参数的值</param>
/// <param name="type">运算符类型</param>
/// <param name="specificType">数据库指定列的类型</param>
protected void SetValue(object val, ExpressionType type)
{
if (val == null)
{
CommandText.Remove(CommandText.Length - 3, 3);
if (type == ExpressionType.Equal)
{
CommandText.Append(" IS NULL");
}
else if (type == ExpressionType.NotEqual)
{
CommandText.Append(" IS NOT NULL");
}
}
else
{
string p_key = Guid.NewGuid().ToString("N");
NpgsqlParameter parameter = new NpgsqlParameter(p_key, val);
Parameters.Add(parameter);
CommandText.Append($"@{p_key}");
}
}
/// <summary>
/// 表达式解析主入口方法，方法重载
/// </summary>
/// <param name="selector">待解析的表达式</param>
/// <param name="parent_type">父级表达式节点类型</param>
private void ExpressionCapture(Expression selector, ExpressionType parent_type)
{
if (selector is BinaryExpression be)
{
ExpressionProvider(be.Left, be.Right, be.NodeType);
}
else if (selector is MemberExpression me)
{
if (!selector.ToString().StartsWith("value(") &&
selector.Type != typeof(DateTime)
||
(
me.Expression != null &&
me.Expression.NodeType == ExpressionType.Parameter &&
!me.ToString().StartsWith("value(") &&
me.Type == typeof(DateTime)
))
{
string tableName = me.Member.DeclaringType == MasterType ? Master_AlisName : Union_AlisName;
if (!string.IsNullOrEmpty(tableName))
{
tableName = tableName + ".";
}
CommandText.Append($"{tableName}{me.Member.Name}");
}
else
{
InvokeExpression(selector, parent_type);
}
}
else if (selector is NewArrayExpression ae)
{
foreach (Expression ex in ae.Expressions)
{
ExpressionCapture(ex, parent_type);
CommandText.Append(",");
}
CommandText.Remove(CommandText.Length - 1, 1);
}
else if (selector is MethodCallExpression callExp)
{
CommandText.Append("(");
switch (callExp.Method.Name)
{
case "Like":
ExpressionCapture(callExp.Arguments[0], parent_type);
CommandText.Append($" ILIKE '%' || ");
ExpressionCapture(callExp.Arguments[1], parent_type);
CommandText.Append(" || '%'");
break;
case "NotLike":
ExpressionCapture(callExp.Arguments[0], parent_type);
CommandText.Append($" NOT ILIKE '%' || ");
ExpressionCapture(callExp.Arguments[1], parent_type);
CommandText.Append(" || '%'");
break;
case "In":
ExpressionCapture(callExp.Arguments[0], parent_type);
In_Not_Parameter(callExp.Arguments[1], "IN");
break;
case "NotIn":
ExpressionCapture(callExp.Arguments[0], parent_type);
In_Not_Parameter(callExp.Arguments[1], "NOT IN");
break;
default:
try
{
InvokeExpression(selector, parent_type);
}
catch (Exception ex)
{
throw new NotSupportedException("使用数据库字段和CLR对象进行函数计算查询时，仅支持 Like,NotLike,In,NotIn 查询", ex);
}
break;
}
CommandText.Append(")");
}
else if (selector is ConstantExpression ce)
{
if (this.Left is UnaryExpression)
{
Type type = ((UnaryExpression)this.Left).Operand.Type;
if (type.BaseType.Name == "Enum")
{
object val = Enum.Parse(type, ce.Value.ToString());
SetValue(val, parent_type, type);
}
else
{
SetValue(ce.Value, parent_type);
}
}
else
{
SetValue(ce.Value, parent_type);
}
}
else if (selector is UnaryExpression ue)
{
ExpressionCapture(ue.Operand, parent_type);
}
else if (selector is ParameterExpression)
{
InvokeExpression(selector, parent_type);
}
else if (selector is NewExpression)
{
InvokeExpression(selector, parent_type);
}
}