How can I print all the column names?
Console.WriteLine(row.RawRow.ETag); does not work it prints blank lines
This is my code so far
static void Main(string[] args)
{
List<string> rows = new List<string>();
string projectId = "project-id 123";
var client = BigQueryClient.Create(projectId);
string sql = #"SELECT * FROM table";
var res = client.ExecuteQuery(sql, parameters: null);
foreach (var row in res)
Console.WriteLine(row["id"])
//rows.Add(row["id"])
}
One of the examples has your answer
Here
public List<T> Execute<T>(string sql)
{
var client = BigQueryClient.Create(projectId);
List<T> result = new List<T>();
try
{
string query = sql;
BigQueryResults results = client.ExecuteQuery(query, parameters: null);
List<string> fields = new List<string>();
foreach (var col in results.Schema.Fields)
{
fields.Add(col.Name);
}
while filling a combobx, I need to convert a Linq-result to a viewmodel.
Actually, I query the records and then I fill a list of the viewmodel in a loop, but that seems to be a bit strange:
public static IEnumerable<ComboBoxActivities> GetActivitySelectList()
{
using(ApplicationDbContext db = new ApplicationDbContext())
{
var result = from activity in db.Activities
where activity.Available
select new
{
ActivityId = activity.Id,
ActivityName = activity.ActivityName,
Available = activity.Available
};
List<ComboBoxActivities> list = new List<ComboBoxActivities>();
foreach(var res in result)
{
ComboBoxActivities listItem = new ComboBoxActivities()
{
ActivityId= res.ActivityId,
ActivityName= res.ActivityName,
Available= res.Available
};
list.Add(listItem);
}
return list;
}
}
Is this really the right way?
I also tried:
var result = from activity in db.Activities
where activity.Available
select new ComboBoxActivities()
{
ActivityId = activity.Id,
ActivityName = activity.ActivityName,
Available = activity.Available
};
But then my razorview crashes with the message that direct binding to a quers (DbSet, DbQuery...) is not supported.
You can convert the IEnumerable<T> to a List<T> by using ToList()
public static List<ComboBoxActivities> GetActivitySelectList()
{
using(ApplicationDbContext db = new ApplicationDbContext())
{
var result = from activity in db.Activities
where activity.Available
select new ComboBoxActivities()
{
ActivityId = activity.Id,
ActivityName = activity.ActivityName,
Available = activity.Available
};
return result.ToList();
}
}
As for loading a ComboBox from a table query, ComboBox has a DataSource property which you can assign the List to.
I have problem
I need to get list from list in linq. But it type of list is unknown on compilation stage.
using(var context = MyDbContext())
{
var list = (from p in context.Employee select p).ToList()
}
I dont know what just property (change Employee)
I want to do something that
public IList<T> GetAll(string propName)
{
using (var context = new ModelContext())
{
return (from p in context.GetType().GetProperty(propName) select p).ToList();
}
}
The DbContext.Database property provides an API that allows you to perform ADO.NET operations directly. The GetDbConnection method returns a DbConnection object representing the context's underlying connection. From that point, you can revert to the familiar ADO.NET APIs:
public dynamic GetAll(string propName)
{
using (var context = new SampleContext())
using (var command = context.Database.GetDbConnection().CreateCommand())
{
//Escape propName to prevent SQL injection
var builder = new SqlCommandBuilder();
string escapedTableName = builder.QuoteIdentifier(propName);
command.CommandText = $"SELECT * From {escapedTableName}";
context.Database.OpenConnection();
using (var dataReader= command.ExecuteReader())
{
var dataTable = new DataTable();
dataTable.Load(dataReader);
return dataTable ;
}
}
}
my problem is very common, but I have not found any solution.
This is my code:
public async Task<QueryResult> RollbackQuery(ActionLog action)
{
var inputParameters = JsonConvert.DeserializeObject<Parameter[]>(action.Values);
var data = DeserailizeByteArrayToDataSet(action.RollBackData);
using (var structure = PrepareStructure(action.Query, action.Query.DataBase, inputParameters))
{
//_queryPlanner is the implementor for my interface
return await _queryPlanner.RollbackQuery(structure, data);
}
}
I need to load DataTable (from whereever) and replace data to database. This is my Rollback function. This function use a "CommandStructure" where I've incapsulated all SqlClient objects. PrepareStructure initialize all objects
//_dataLayer is an Helper for create System.Data.SqlClient objects
//ex: _dataLayer.CreateCommand(preSelect) => new SqlCommand(preSelect)
private CommandStructure PrepareStructure(string sql, string preSelect, DataBase db, IEnumerable<Parameter> inputParameters)
{
var parameters = inputParameters as IList<Parameter> ?? inputParameters.ToList();
var structure = new CommandStructure(_logger);
structure.Connection = _dataLayer.ConnectToDatabase(db);
structure.SqlCommand = _dataLayer.CreateCommand(sql);
structure.PreSelectCommand = _dataLayer.CreateCommand(preSelect);
structure.QueryParameters = _dataLayer.CreateParemeters(parameters);
structure.WhereParameters = _dataLayer.CreateParemeters(parameters.Where(p => p.IsWhereClause.HasValue && p.IsWhereClause.Value));
structure.CommandBuilder = _dataLayer.CreateCommandBuilder();
structure.DataAdapter = new SqlDataAdapter();
return structure;
}
So, my function uses SqlCommandBuilder and DataAdapter to operate on Database.
PreSelectCommand is like "Select * from Purchase where CustomerId = #id"
The table Purchase has one primaryKey on ID filed
public virtual async Task<QueryResult> RollbackQuery(CommandStructure cmd, DataTable oldData)
{
await cmd.OpenConnectionAsync();
int record = 0;
using (var cmdPre = cmd.PreSelectCommand as SqlCommand)
using (var dataAdapt = new SqlDataAdapter(cmdPre))
using (var cmdBuilder = new SqlCommandBuilder(dataAdapt))
{
dataAdapt.UpdateCommand = cmdBuilder.GetUpdateCommand();
dataAdapt.DeleteCommand = cmdBuilder.GetDeleteCommand();
dataAdapt.InsertCommand = cmdBuilder.GetInsertCommand();
using (var tbl = new DataTable(oldData.TableName))
{
dataAdapt.Fill(tbl);
dataAdapt.FillSchema(tbl, SchemaType.Source);
tbl.Merge(oldData);
foreach (DataRow row in tbl.Rows)
{
row.SetModified();
}
record = dataAdapt.Update(tbl);
}
}
return new QueryResult
{
RecordAffected = record
};
}
I Execute the code and I don't have any errors, but the data are not updated.
variable "record" contain the right number of modified (??) record, but..... on the table nothing
can someone help me?
EDIT 1:
With SQL Profiler I saw that no query is executed on DB. Only select query on .Fill(tbl) command.
EDIT 2:
Now I have made one change:
tbl.Merge(oldData) => tbl.Merge(oldData, true)
so I see perform the expected query but, with reversed parameters.
UPDATE Purchase SET price=123 where id=6 and price=22
instead of
UPDATE Purchase SET price=22 where id=6 and price=123
In MVC 4 and EF 5 i want to run dynamic query.
var returndata = Context.Database.SqlQuery(Type, strsql, null);
i don't know, how many fields it will return and name. Out of this result i want to make table structure that will display on view.
Question : What should i passed as Type?
my query return below result:
Field 1, Field 2, Field 3, Field 4, Field 5
Row1...
Row2..
Appreciate any suggestion.
You could use a raw SQL query because EF doesn't support that:
private static IEnumerable<object[]> Read(DbDataReader reader)
{
while (reader.Read())
{
var values = new List<object>();
for (int i = 0; i < reader.FieldCount; i++)
{
values.Add(reader.GetValue(i));
}
yield return values.ToArray();
}
}
and then:
public ActionResult Index()
{
using (var ctx = new UsersContext())
using (var cmd = ctx.Database.Connection.CreateCommand())
{
ctx.Database.Connection.Open();
cmd.CommandText = "SELECT * FROM UserProfile";
using (var reader = cmd.ExecuteReader())
{
var model = Read(reader).ToList();
return View(model);
}
}
}
and finally in your view:
#model IEnumerable<object[]>
<table>
<tbody>
#foreach (var row in Model)
{
<tr>
#foreach (var column in row)
{
<td>#column</td>
}
</tr>
}
</tbody>
</table>
This method loads data from SQL select (with parameters) to the list of rows, where each row is the dictionary of columns (the key is the column name).
private static List<Dictionary<string, object>> LoadData(string sqlSelect, params object[] sqlParameters)
{
var table = new List<Dictionary<string, object>>();
using (var ctx = new DbEntities())
{
ctx.Database.Connection.Open();
using (var cmd = ctx.Database.Connection.CreateCommand())
{
cmd.CommandText = sqlSelect;
foreach (var param in sqlParameters)
cmd.Parameters.Add(param);
using (var reader = cmd.ExecuteReader())
{
while (reader.Read())
{
var row = new Dictionary<string, object>();
for (int i = 0; i < reader.FieldCount; i++)
row[reader.GetName(i)] = reader[i];
table.Add(row);
}
}
}
}
return table;
}
Finally i made is using TypeBuilder option suggested by "Mortalus" and ExpandoObject object. It has little performance overhead right now.
Take Typebuilder code from "Mortalus" answer then i made code according to my requirement as below.
List<Dictionary<string, object>> expandolist = new List<Dictionary<string, object>>();
foreach (var item in returndata)
{
IDictionary<string, object> expando = new ExpandoObject();
foreach (PropertyDescriptor propertyDescriptor in TypeDescriptor.GetProperties(item))
{
var obj = propertyDescriptor.GetValue(item);
expando.Add(propertyDescriptor.Name, obj);
}
expandolist.Add(new Dictionary<string, object>(expando));
}
return expandolist;
so now, I have "Dictionary" object from dynamic object. and using it you can work easily at design time rather then wait until runtime using "dynamic" object.
I have recently stumbled upon this example:
http://www.markzhou.com/blog/post/2011/06/02/Use-dynamic-type-in-Entity-Framework-41-SqlQuery()-method.aspx
I haven't had the time to test it myself but it seems that it is possible with some additional work to construct the dynamic type.
In short you would want to do something like this:
TypeBuilder builder = Program.CreateTypeBuilder(
"MyDynamicAssembly", "MyModule", "MyType");
Program.CreateAutoImplementedProperty(builder, "name", typeof(string));
Program.CreateAutoImplementedProperty(builder, "type", typeof(string));
Program.CreateAutoImplementedProperty(builder, "id", typeof(int));
Type resultType = builder.CreateType();
dynamic queryResult = context.Database.SqlQuery(
resultType, "SELECT * FROM sys.sysobjects");
Where TypeBuilder is described in details in the post I have attached.
Without knowing anything about the type that is returned, I think you might be out of luck.
If you know what patterns it might fall under, you could use some try { } catch () { }'s on interfaces that match those parameters on your otherwise dynamic query, but that seems like it might be a bit painful.
Unfortunately, EF won't materialize objects unless it knows their Type.
If this is really necessary for you, I think your best bet would be to fall back to ADO.NET and DataTable.
Similarly post by Darin Dimitrov, but it returns DataTable
public DataTable QueryToTable(Entities db, string queryText, SqlParameter[] parametes)
{
using ( DbDataAdapter adapter = new SqlDataAdapter())
{
adapter.SelectCommand = db.Database.Connection.CreateCommand();
adapter.SelectCommand.CommandText = queryText;
if (parametes != null)
adapter.SelectCommand.Parameters.AddRange(parametes);
DataTable table = new DataTable();
adapter.Fill(table);
return table;
}
}
Use
SqlParameter[] parametes = new[]
{
new SqlParameter("date_from", dateFrom)
};
DataTable tab = QueryToTable(new Entities(),
"Select * From SomeTable Where ADate >= #date_from", parametes);
Example for MS SQL Server
Adding to Petr VobornÃk's answer, dynamic query, I add dynamic insert of ResultSet, my application takes the dynamic query of all tables of the entire database, a chunk at a time and then inserts the dynamic results into a remote database, using Always Encrypted (omitted here). Passing a sb command and parameter object.
public void StoreData(DbContext dbContext, Dictionary<string, string> columnInfo, List<Dictionary<string, object>> multiInsertObj, string tableName)
{
_ctx = dbContext;
_columnInfo = columnInfo;
var sb = new StringBuilder();
sb.Append(BuildSqlCommand(tableName, columnInfo, multiInsertObj.Count));
ExecuteSqlCommand(sb, GetParamsObject(columnInfo, multiInsertObj));
}
private static StringBuilder BuildSqlCommand(string tableName, Dictionary<string, string> variableInfo, int variableCount)
{
//Build sql command
var sb = new StringBuilder();
sb.Append("INSERT INTO dbo." + tableName + "(");
foreach (var variable in variableInfo)
{
sb.Append(variable.Key);
sb.Append(", ");
}
sb.Append("SystemNumber, ");
sb.Remove(sb.Length - 2, 2).Append(") VALUES ");
for (var i = 0; i < variableCount; i++)
{
sb.Append("(");
foreach (var name in variableInfo.Keys)
{
sb.Append("#" + name + "_" + i + ",");
}
sb.Append("#SystemNumber" + "_" + i + ",");
sb.Remove(sb.Length - 1, 1).Append("),");
}
sb.Remove(sb.Length - 1, 1);
return sb;
}
private static object[] GetParamsObject(Dictionary<string, string> columnInfo, List<Dictionary<string, object>> multiInsertObj)
{
var variableCount = multiInsertObj.Count;
var rowCount = multiInsertObj[0].Keys.Count;
var objectLength = (rowCount + 1) * variableCount;
var variableDataTypes = columnInfo.Values.ToList();
var paramObj = new object[objectLength];
var j = 0;
var i = 0;
foreach (var row in multiInsertObj)
{
var k = 0;
foreach (var data in row)
{
var sb = new StringBuilder();
sb.Append("#");
sb.Append(data.Key);
sb.Append("_" + i);
paramObj[j] = new SqlParameter(sb.ToString(), SetSqlDataType(variableDataTypes[k])) { Direction = Input, Value = data.Value };
j++;
k++;
}
paramObj[j] = new SqlParameter(("#SystemNumber" + "_" + i), SetSqlDataType("int")) { Direction = Input, Value = _systemNumber };
i++;
j++;
}
return paramObj;
}
private static void ExecuteSqlCommand(StringBuilder sb, params object[] sqlParameters)
{
using (_ctx)
{
_ctx.Database.Connection.Open();
using (var cmd = _ctx.Database.Connection.CreateCommand())
{
cmd.CommandText = sb.ToString();
foreach (var param in sqlParameters)
cmd.Parameters.Add(param);
try
{
cmd.ExecuteNonQuery();
}
catch (Exception e)
{
Console.WriteLine(e);
throw;
}
}
}
}
These approaches seemed a bit complicated to me, at least in my situation. All I needed was to return a DataTable so it could be previewed. Meaning every value could be a string.
So I created two classes:
public class DynamicResultModel
{
public DynamicResultColumnModel headers = new();
public List<DynamicResultColumnModel> rows = new();
}
public class DynamicResultColumnModel
{
public List<string> columns = new();
}
Then created a simple helper class to basically serialize and deserialize a DataTable into and out of a DynamicResultModel
public static DynamicResultModel DataTableToDynamic(DataTable dtData)
{
DynamicResultModel result = new();
DynamicResultColumnModel headers = new();
foreach (DataColumn col in dtData.Columns)
{
result.headers.columns.Add(col.ColumnName);
}
foreach (DataRow row in dtData.Rows)
{
DynamicResultColumnModel rowData = new();
foreach (var item in row.ItemArray)
{
rowData.columns.Add(item.ToString());
}
result.rows.Add(rowData);
}
return result;
}
The only caveat was that I could not return a DynamicResultModel from my controller, I had to serialize it into a string first. Regardless, this worked for me and saved me a lot of time.
So my API endpoint definition was
Task<ApiResponse<string>>
Instead of
Task<ApiResponse<DynamicResponseModel>>