How to get list of column per table passed to function ?

Question

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Problem

I work on asp.net core 2.1 project and i need to design function pass to it table name

get columns exist on that table ?

suppose i have table employee have two column employeeid,employeename

then when pass table name employee to function will return two columns

employeeid,employeename .

C#

public List<string> GetColumns<T>(How to pass table name here as string)
        {
            var columnNames = _context.Model.FindEntityType(typeof(T))
                   .GetProperties().Select(x => x.Relational().ColumnName).ToList();
            return columnNames;
        }

How to pass table name as string in function above
i try but it give me compile error
on T

What I have tried:

public List<string> GetColumns<T>(List<T> _)
       {
           var columnNames = _context.Model.FindEntityType(typeof(T))
                  .GetProperties().Select(x => x.Relational().ColumnName).ToList();
           return columnNames;
       }

Posted 11-Mar-19 6:07am

ahmed_sa

Updated 11-Mar-19 6:36am

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Comments

[no name] 11-Mar-19 12:18pm

(List<t> _)

What's that supposed to mean? This is a "string": string name

ahmed_sa 11-Mar-19 12:19pm

public List<string> GetColumnNames(string tablename)
{

ahmed_sa 11-Mar-19 12:21pm

public List<string> GetColumnNames(string tablename)
{
var columnNames = _context.Model.FindEntityType(typeof(T))
.GetProperties().Select(x => x.Relational().ColumnName).ToList();
return columnNames;
}

ahmed_sa 11-Mar-19 12:21pm

I GET ERROR ON T

1 solution

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MadMyche · Answer 1 · 2019-03-11T06:36:00

Why don't you work off of Saturday's question
How to get fields exist on table by passing table name by using ASP.NET core 2.1 ?[^]

To build onto that
1. Create a new Model which mirrors the basics of the sql system table which has the column information, Information_Schema.Columns. While Entity Framework may not like working with that table, you can always use ADO.

SQL

SELECT  TABLE_SCHEMA, TABLE_NAME, COLUMN_NAME, DATA_TYPE
     ,  CHARACTER_MAXIMUM_LENGTH, NUMERIC_PRECISION, NUMERIC_SCALE
FROM    INFORMATION_SCHEMA.COLUMNS
WHERE   (TABLE_SCHEMA <> 'sys')

2. When you want to run your function, you can populate a collection of that new Model, and use LINQ or whatever you want to perform the search.

This approach would also allow you to find all tables that have a particular named column.