How can return string from database using dapper

Question

I tried but it gives this error

Must declare the scalar variable "@imageid"

controller.cs

    [HttpGet]
    [Route("download/{id:int}")]
    public String Getfiles(int imageid)
    {

        return _ShopDataProvider.DownloadImage(imageid);

    }

class.cs

public String  DownloadImage(int imageid)
    {
        using(IDbConnection dbConnection = Connection)
        {

            string sQuery0 = "SELECT path FROM Shop WHERE ShopId = @imageid";
            dbConnection.Open();
            String Path = dbConnection.QueryFirstOrDefault<String>(sQuery0, new { ShopId = imageid });

            return Path;
        } 
    }

Daniel Mann · Accepted Answer · 2018-10-27 17:46:36Z

2

You're declaring a parameter in your SQL query named @imageid but not providing a value for it. You're providing a value for the parameter @ShopID (new { ShopId = imageid }), which your SQL query doesn't use.

Change new { ShopId = imageid } to new { imageid = imageid }

Please refer to the documentation.

answered Oct 27, 2018 at 17:46

Daniel Mann

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4 Comments

Dulanga Heshan Over a year ago

there are values in my DB error is fixed but return string is null when i changed SELECT path FROM Shop WHERE ShopId = @imageid to Select ShopName ..etc

Dulanga Heshan Over a year ago

String Path = dbConnection.QueryFirstOrDefault<String>(sQuery0, new { imageid = 1 }); it return me a values but String Path = dbConnection.QueryFirstOrDefault<String>(sQuery0, new { imageid = imageid }); it doesnt return value

Daniel Mann Over a year ago

@DulangaHeshan Use a debugger. Look at the value of imageid. Does it have the value you're expecting?

Dulanga Heshan Over a year ago

yes thnks i fixed error was [Route("download/{id:int}")] here thank you very much brother

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