making a new list with comparing a list with the Field of a Table-CodePudding

I have a list of string

 List<string> totalTags =new ({"Test1","test2","Test3","test4","Test5"});

I want to search the table Tags and find list of following Name and make a list for their associated Ids The Tag Table has two fields ,Id and Name. like

  Id     Name
 ==============
   1      Test1
   2      Test4

and so on

  var IdList= _context.Tags.Where(t2 => !totalTags .Any(t1 => t2.Name.Contains(t1))).Select(p=>p.Id).ToList();

and want to have

  IdList ={"1","2",....}     (the Id of the rest)

but it doesn't work

CodePudding user response：

I think you might want to compare t1 == t2.Name in Any becasue t2.Name is a string instead of list, otherwise that will compare by char.

var IdList = _context.Tags.Where(t2 => totalTags.Any(t1 => t1 == t2.Name)).Select(p => p.Id).ToList();

CodePudding user response：

If you want to select all ids from _context.Tags where tag.Name should present in totalTags list, then try below

 var IdList = _context.Tags`
     .Where(x => totalTags.Contains(x.Name)) //No `!` operator
     .Select(x => x.Id)
     .ToList();

CodePudding user response：

You should use Contains method like

var idsList = _context.Tags
                      .Where(t=> totalTags.Contains(t.Name))
                      .Select(t=> t.Id)
                      .ToList()