Does GORM support IIF functions using SQL?

Question

I have a table for assignments, a table for solutions, and a table for students. I want to retrieve all assignments, and for each assignment I want to add a "flag" that shows if the currently logged in student has attempted the assignment.

I tried this:

import (
   "fmt"
   "gorm.io/gorm"
   "encoding/json"
   "github.com/my_organisation/myorg-repo/db"
)

var database *gorm.DB

var solutions[]db.Solution
var listOfAsnmtIDs []uint

func myfuncn (w http.ResponseWriter, r *http.Request){
   //...
   _ = database.Table("solutions").Where("pupil_id = ?",
   pupil.ID).Select("assignment_id").Find(&solutions)
    
    for _, solution := range solutions {
        listOfAsnmtIDs = append(listOfAsnmtIDs, solution.AssignmentID)
    }

response := database.Table("assignments").Select(`id, created_at, IIF((id IN ?), 'attempted', 'Not attempted') as attempted`, listOfAsnmtIDs).Find(&allAssignments)

if response.RowsAffected < 1 {
   respondToClient(w, 404, nil, "No assignments found")
   return
 }
//...
}

Answer 1

You only need to list the parameters. Similar to this

    var mad string
    for i, solution := range solutions {
        mad += strconv.FormatUint(uint64(solution.AssignmentID), 10)
        if i != len(solutions) {
            mad += ","
        }
        listOfAsnmtIDs = append(listOfAsnmtIDs, solution.AssignmentID)
    }

    response := database.Table("assignments").Select(`id, created_at, IIF((id IN ?), 'attempted', 'Not attempted') as attempted`, mad).Find(&allAssignments)