Create KeyValuePair<TKey, TValue> from columns in a single data row - sql-server

Question

I have the following table in Sql Server that stores the permissions the Foreign Key UserId has to the Foreign Keyed BlogId. What I would like to do is write a query with Dapper that takes each column after BlogId and returns it as a KeyValuePair<TKey, TValue>.
CREATE TABLE [dbo].[UserPermission] (
[UserPermissionId] INT IDENTITY (1, 1) NOT NULL,
[BlogId] INT NOT NULL,
[UserId] INT NOT NULL,
[CanCreateNewPosts] BIT NOT NULL,
[CanEditExistingPosts] BIT NOT NULL,
[CanDeleteExistingPosts] BIT NOT NULL,
[CanPublishDraftPosts] BIT NOT NULL,
CONSTRAINT [PK_UserPermission] PRIMARY KEY CLUSTERED ([UserPermissionId] ASC),
CONSTRAINT [FK_UserPermission_Blog] FOREIGN KEY ([BlogId]) REFERENCES [dbo].[Blog] ([BlogId]),
CONSTRAINT [FK_UserPermission_User] FOREIGN KEY ([UserId]) REFERENCES [dbo].[User] ([UserId])
);
I would like to query via Dapper like this:
using (var connection = new SqlConnection(this.connectionString))
{
string sql = "SELECT * FROM [Permission] WHERE UserId = #UserId";
await connection.OpenAsync();
IEnumerable<KeyValuePair<string, bool>> results = await connection.QueryAsync(
sql,
new { UserId = this.userId });
}
var p1 = results.First();
var p2 = results.Skip(1).First();
In the above example, I would like p1 to result in a KeyValuePair with the Key being CanCreateNewPosts and the Value being the column value, either true or false. Same applies with p2, where the Key would be CanEditExistingPosts, with it's corresponding value.
The underlying need for this is to simplify transforming the record into a list of Claims in Identity, one claim per column.
I looked at splitOn:, to try and split after the UserId column but that doesn't seem like it's what I want. It would require n-generic arguments for each column I split. Ideally I'd like to add columns to this table in the future and my security/data/servicing layer just handles turning it into a Claim - letting me just focus on the Controller Action that needs to check for the claim. Having the query and Dapper return map the column-name/values into a collection of KeyValuePairs would facilitate that need for me.

Answer 1

You can use the SQL UNPIVOT operation to transform columns into column values. Here's an example for your particular case:
SELECT u.BlogId, u.permission
FROM UserPermissions up
UNPIVOT
(
permission for perms in (
CanCreateNewPosts,
CanEditExistingPosts,
CanDeleteExistingPosts,
CanPublishDraftPosts
)
) u;