I am looking for a function that manages programmatically the parameters in a GET, to create DB quer...

# ktor

[Francesco Di Sciascio]

I am looking for a function that manages programmatically the parameters in a GET, to create DB queries dynamically.
At the moment, i have the following:

route("/sCap"){
    val dao: DAOFacade = DAOFacadeImpl()
    get{      
        val codiceParam = call.request.queryParameters["codice"]
        val listSCap = dao.allSCapFiltered(codiceParam)
        if(listSCap.isEmpty())
            call.respondText("Nessun elemento trovato", status = HttpStatusCode.NotFound)
        else
            call.respond(listSCap)
    }
...
}

and in the DAO:

override suspend fun allSCapFiltered(codice: String?): List<SCap> {
    return if(codice.isNullOrEmpty()){
        DatabaseFactory.dbQuery {
            S_Cap.selectAll().map(::resultRowToSCap)
        }
    } else {
        DatabaseFactory.dbQuery {
            S_Cap
                .select { S_Cap.codice like "%$codice%" }
                .map(::resultRowToSCap)
        }
    }
}

is there a way to manage all the parameters expected dynamically, based on properties of data class?

data class SCap(val idcap: Int?,
                    val regione: String?,
                    val prov: String?,
                    val comune: String?,
                    val cap: Int?,
                    val codice: String?
                    )

Thanks everyone for suggestions!

[Aleksei Tirman [JB]]

Do you mean to map query parameters to the properties of the SCap data class?

[Francesco Di Sciascio]

yes, map and create the select properly, based on parameters passed in call (only the ones with value)

[Aleksei Tirman [JB]]

So what is the problem with having functions that transform query parameters to an object of the data class and that object to a select statement?

[Francesco Di Sciascio]

No problem indeed...my problem was that I haven't thought about that simple solution!
But what do you suggest to use to do that transformation properly?

[Francesco Di Sciascio]

In particular, how to create the select properly (I've created a function that maps the Parameters to SCap)

[Francesco Di Sciascio]

I've tried to create a function that allows me to create a query in a dynamic way, but I miss the part in which I add an "andPart" in the query...here is the partial code:

parameters.forEach { it, list ->
    for(property in S_Cap::class.declaredMemberProperties){
        if(property.name == it) {            parameters["$it"]?.let{query.andWhere { ??? }}
        }
    }

}

parameters is of type io.ktor.http.Parameters

[Francesco Di Sciascio]

any suggestion?