Dapper Query() returned multiple same column

Question

I'm using dapper Query method to fetch a set of data from sqlite with left join, it does return the column i need but multiple times.

i tried these query on DB Browser it works fine,

 string sql =
         @"select a.id, a.alert_tag, lyr.layer_name, ln.line_name, t.task_name from alert_tag a
              LEFT JOIN layer_group lyr on lyr.layerID = a.layer_group
              LEFT JOIN line ln on ln.lineID = a.line
              LEFT JOIN task t on t.taskID = a.task";

then i call it,

using (IDbConnection cnn = new SQLiteConnection(Tools.LoadConnectionString()))
{
    var output = cnn.Query<dynamic>(sql);
    return output.ToList();
}

List<dynamic> Alerttag_List = new List<dynamic>();

private void LoadDGVdata()
{
     Alerttag_List = SqliteQuery_AlertTagModel.Load();
     dgv_AlertTag.DataSource = Alerttag_List;
}

I expected to get result like these

| id | alert_tag | layer_name | line_name | task_name |

but i got these

| id | alert_tag | layer_name | line_name | task_name | id | alert_tag | layer_name | line_name | task_name |

What happens when you run the query directly against the database — Chetan
– Chetan, Commented May 15, 2019 at 10:37
This sounds like a problem with the grid binding, to be honest. Can you do: var propCount = TypeDescriptor.GetProperties(Alerttag_List[0]).Count and tell me what it says? is it 5, or is it 10? — Marc Gravell
– Marc Gravell, Commented May 15, 2019 at 10:47
also: how many rows are there in this example? is it 2 perhaps? I wonder whether the grid is generating a column per unique PropertyDescriptor reference, but the RowBoundPropertyDescriptor that dapper is exposing here is transient (generated on the fly per row). Also: what kind of grid is that? i.e. is this DataGridView ? or...? And: does this perhaps gain columns, i.e. you have AutoGenerateColumns (or whatever) enabled, and it is adding them whenever you change the source? — Marc Gravell
– Marc Gravell, Commented May 15, 2019 at 10:50
Side note: generating a POCO class and mapping to that (i.e. Query<YourType>) should be very reliable - the dynamic property API via PropertyDescriptor however, is... twitchy — Marc Gravell
– Marc Gravell, Commented May 15, 2019 at 10:52

Chandra Shakar · Accepted Answer · 2020-08-14 19:35:04Z

1

You can use: ExecuteReader. it will return single data. Example:

public dynamic GetTableData(string schemaName, string tableName)
        {
            string sql = $@"select * from {schemaName}.{tableName}";
            var tableData = _sqlConnection.ExecuteReader(sql);
            return tableData;
        }

edited Aug 14, 2020 at 19:35

answered Aug 14, 2020 at 17:20

Chandra Shakar

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3 Comments

Marc Gravell Over a year ago

ExecuteReader is not compatible with dynamic AFAIK (context: I wrote it). And even if it was, I don't think that is the problem here.

Chandra Shakar Over a year ago

ExecuteReader from dapper. I have already tested. and edited the answer with a picture.

deveton Over a year ago

Hello Marc, Maybe same thing but for bindable grid/treelist problem happens. stackoverflow.com/questions/66096906/…

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