I'm trying to figure out if there's a way to update an object in one shot with Dapper rather than having to write out every variable/field alignment. Here's an example of what I'm doing now, which is to explicitly spell out each field:
public string UpdateAttributes(List<ItemAttribute> attributesList)
{
try
{
using (IfxConnection con = new IfxConnection(WebConfigurationManager.AppSettings["LOKICONN"].ToString()))
{
con.Open();
foreach (ItemAttribute item in attributesList)
{
con.Execute("update oe_cnvwrk set cwr_response = ?, cwr_uom = ? where cwr_genero = ? and cwr_line = ?",
new { cwr_response = item.cwr_response, cwr_uom = item.cwr_uom, cwr_genero = item.cwr_genero, cwr_line = item.cwr_line });
}
con.Close();
return "success";
}
}
catch (Exception x)
{
return x.ToString();
}
}
Is there a way to skip spelling out each variable and simply reference the object? Or a better way to approach this period? Dapper allows for dynamically creating an object with a query, and for populating the values of a pre-defined object, but for updating an existing object I'm not finding any documentation or examples. With a larger object that becomes a bit of a pain, as does maintenance if the table and object need to be changed.
This might work:
using (IfxConnection con = new IfxConnection(WebConfigurationManager.AppSettings["LOKICONN"].ToString()))
{
con.Execute("update oe_cnvwrk set cwr_response = ?cwr_response?, cwr_uom = ?cwr_uom? where cwr_genero = ?cwr_genero? and cwr_line = ?cwr_line?", attributesList);
return "success";
}
Changes:
no need to open/close the connection
passes the sequence directly; no need to loop
uses the special dapper ?foo? syntax, which maps named members from the available data to positional SQL; this will be re-written to use positional ? sql, but adding the expected parameters in the expected order
Related
I have a fairly agnostic ADO.NET application that connects to a number of databases and is able to extract the necessary information to run. I have hit a snag with DB2 and how it handles named parameters, particularly when I reuse a named parameter in the same query. I know of a couple of ways to get around this by simply adding more parameters, but in theory it should work as it does on other databases that I connect to as the parameter name is the same.
What I'm doing is a bit more complicated and involves subqueries etc, but to demonstrate, take the following query:
select value from test.table where cola=#key1 and colb=#key1;
The named parameter #key1 is used twice.
My code is as follows:
try
{
DbProviderFactory dbfFactory = DbProviderFactories.GetFactory("IBM.Data.DB2.iSeries");
using (DbConnection dbConnection = dbfFactory.CreateConnection())
{
dbConnection.ConnectionString = "DataSource=xxx.xxx.xxx.xxx;UserID=xxxxxxxx;password=xxxxxxxxx";
using (DbCommand dbCommand = dbConnection.CreateCommand())
{
IDbDataParameter iddpParameter1 = dbCommand.CreateParameter();
iddpParameter1.ParameterName = "#key1";
iddpParameter1.DbType = DbType.String;
iddpParameter1.Value = "1";
dbCommand.Parameters.Add(iddpParameter1);
dbCommand.CommandType = CommandType.Text;
dbCommand.CommandText = "select value from test.table where cola=#key1 and colb=#key1";
dbConnection.Open();
using (IDataReader idrReader = dbCommand.ExecuteReader())
{
while (idrReader.Read())
{
...
}
}
}
} // end dbConnection
} // end try
catch (Exception ex)
{
Console.Write(ex.Message);
}
When I run this I get an exception that tells me:
System.InvalidOperationException: Not enough parameters specified. The command requires 2 parameter(s), but only 1 parameter(s) exist in the parameter collection.
I get what it is telling me, but I'm looking for help in figuring out how I can have the provider use the named parameter for both parameters as they are the same. It seems that it is doing a blind count of named parameters and not realizing that they are the same named parameters. SQL Server seems to allow me to do this with the same code above. I'm guessing it's just one of those differences in the providers, but hoping someone has run into this and has a solution for DB2 that doesn't get into specific DB2 code.
Thanks, appreciate the assistance.
well I did a little more digging, and I wonder if it might be the connector that you are using. So I'm doing the following (which is very similar to what you are doing)
in my app config file I have
<connectionStrings>
<add name="AWOLNATION" providerName="Ibm.Data.DB2" connectionString="Server=sail:50000;Database=Remix;" />
</connectionStrings>
in my Databasemanager class I would initialize it like so
public static DatabaseManager Instance(string connectionStringName)
{
var connectionStringSettings = ConfigurationManager.ConnectionStrings[connectionStringName];
if (connectionStringSettings == null) throw new MissingMemberException("[app.config]", string.Format("ConnectionStrings[{0}]", connectionStringName));
return new DatabaseManager(connectionStringSettings);
}
private DatabaseManager(ConnectionStringSettings connectionInformation)
{
_connectionInformation = connectionInformation;
_parameters = new Dictionary<string, object>();
}
private void Initialize()
{
_connection = DbProviderFactories.GetFactory(_connectionInformation.ProviderName).CreateConnection();
_connection.ConnectionString = _connectionInformation.ConnectionString;
_command = _connection.CreateCommand();
}
I add parameters a little different though. I have a Dictionary<string,object> that I add too when setting up my query. To use your example I would have had this
public IEnumerable<object> GetSomething(string key)
{
var sql = "select value from test.table where cola = #key1 and colb = #key1";
_manager.AddParameter("#key1", key);
return _manager.ExecuteReader<object>(sql, ToSomethignUseful);
}
private object ToSomethignUseful(DatabaseManager arg)
{
return new { Value = arg.GetArgument<object>("value") };
}
then reading is where the OP and I have similar code
public IEnumerable<T> ExecuteReader<T>(string sql, Func<DatabaseManager, T> conversionBlock)
{
Initialize();
using (_connection)
{
_connection.Open();
_command.CommandText = sql;
_command.CommandType = CommandType.Text;
if (_parameters.Count > 0)
AddParameters(_command, _parameters);
_parameters.Clear();
using (_reader = _command.ExecuteReader())
{
while (_reader.Read())
{
yield return conversionBlock(this);
}
}
}
}
private static void AddParameters(DbCommand command, Dictionary<string, object> parameters)
{
foreach (var param in parameters)
{
command.Parameters.Add(CreateParameter(command, param.Key, param.Value));
}
}
private static DbParameter CreateParameter(DbCommand command, string key, object value)
{
var parameter = command.CreateParameter();
parameter.ParameterName = key;
parameter.Value = value;
return parameter;
}
running said code is working for me, so I wonder if the difference is in the provider that we are using. I'm using named parameters in production and have been for atleast a year now, possibly closer to 2 years.
I will say that I did get the same error when essentially running the same code twice, as shown in this code
public static void IndendedPrintForEach<T>(this IEnumerable<T> array, string header, Func<T, string> consoleStringConverterMethod)
{
var list = array.ToList();
var color = Console.ForegroundColor;
Console.ForegroundColor = ConsoleColor.Magenta;
Console.WriteLine($"<<<{header}>>>");
Console.ForegroundColor = color;
if (!list.Any())
{
Console.ForegroundColor = ConsoleColor.DarkRed;
Console.WriteLine(" ************NoItemsFound************");
Console.ForegroundColor = color;
}
else
{
foreach (var item in list)
Console.WriteLine($" {consoleStringConverterMethod(item)}");
}
}
on line 3 var list = array.ToList() was the fix to the problem that you were seeing for me. before I had if (!array.Any()) which would run the query and use the parameters (which I clear out before I execture the query) then when I go to enumerate through and print each item in the array I was then getting the error. For me the problem was that it was re-running the query which I had no more parameters. The fix was to enumerate the query with the ToList() and then do my checking and printing on the list.
You answered you own question: "Unfortunately, I have not found a solution. I had to create another named parameter and just assign it the same value"
Oracle/DB2/Sybase especially are difficult with SQL queries and parameters.
Parameters in the SQL query should be in the same order they are added to the C# parameters are added to the C# SQL command (Oracle, Sybase)
Put parenthesis around the SQL query where clause parts using parameters (all)
Make sure the SQL data types are matching the C# parameter data types (all)
Check for overflow/underflow of parameter data so that the SQL query does not error
Pass in null/empty string in the appropriate format for the database. Ideally, create C# SQLParameter create methods to create the parameter in the correct format for the database
Oracle is particularly finicky about this. Take the time to build a C# wrapper library to construct a C# query object correctly, construct C# parameters correctly and add the C# SQL parameters to the query.
Put in notes that the query parameter add order should match the order of "#" parameters in the SQL query.
This wrapper library is you documentation for you and the next developer to avoid the problems you've encountered.
I'm looking for the absolute easiest way to call stored procedures from C# without explicit parameter objects, like so:
using (DataTable dt=conn.ExecuteQuery("MySP", param1, "param2", p3, p4)) {
On first invocation the library queries the DB schema for the SP signature then caches it for subsequent calls.
A) Is there any way to do it THIS SIMPLY with the Enterprise Library Data Access Block?
B) I don't find ORMs attractive because of synchronization issues between schema and code metadata.
I DID find this generator-less wrapper but am hoping there is a major library or best practice I somehow just haven't discovered yet.
I do have an example of an SqlDataReader where the Function call is
ExecuteNonQuery("dbo.[Sp_Skp_UpdateFuncties]", parameters);
This is in a class DataBaseManager which hold the databaseconnectionstring
public classDataBaseManager
{
...
public int ExecuteStoredProcedure(string storedprocedureNaam, IEnumerable<KeyValuePair<string, object>> parameters)
{
var sqlCommand = new SqlCommand
{
Connection = DatabaseConnectie.SqlConnection,
CommandType = CommandType.StoredProcedure,
CommandText = storedprocedureNaam,
};
foreach (KeyValuePair<string, object> keyValuePair in parameters)
{
sqlCommand.Parameters.Add(
new SqlParameter { ParameterName = "#" + keyValuePair.Key, Value = keyValuePair.Value ?? DBNull.Value }
);
}
if (sqlCommand == null)
throw new KoppelingException("Stored procedure ({0}) aanroepen lukt niet", storedprocedureNaam);
return sqlCommand.ExecuteNonQuery();
}
....
}
Dapper?
var rows = conn.Query("procname",
new { name = "abc", id = 123 }, // <=== args, fully named and typed
commandType: CommandType.StoredProcedure
).ToList();
The above is the dynamic API which allows automatic binding to column names:
foreach(var row in rows) {
int x = row.X; // look ma, no column mappings
string y = row.Y;
//...
}
But you can also use Query<SomeType> and it will populate an object model for you. When binding to an object model it includes all the meta-programming / caching you might expect from people obsessive-compulsive about performance. Hint: I usually use the generic API - it is very very fast.
TL;DR I'm using EntityFramework 5.0 with Oracle and need to query a table for two columns only using index with NVL of two columns.
Details after hours of attempts... I'll try to organize it as possible.
The desired SQL query should be:
SELECT t.Code, NVL(t.Local, t.Global) Description
FROM Shows t
Where t.Code = 123
So what is the problem? If I want to use Context.Shows.Parts.SqlQuery(query) I must return the whole row(*), but then I get Table Access Full, so I must return only the desired columns.
The next thing(Actually there were a lot of tries before the following...) that I've tried which gives a very close results was using the null-coalescing operator(??) :
Context.Shows.Where(x => x.Code == 123)
.Select(x => new { x.Code, Description = x.Local ?? x.Global);
But the SQL it's using is complicated using case & when and not using my Index on Code, Nvl(Local, Global) which is critical!
My next step was using Database.SqlQuery
context.Database.SqlQuery<Tuple<int, string>>("the Raw-SQLQuery above");
But I get an error that Tuple must not be abstract and must have default ctor(it doesn't).
Final step which I dislike is creating a class which has only those two properites(Code, Description), now... it works great, but I don't want to write a class for each query like that.
Ideas?
This is a no-solution answer.
I think whatever you try, you can't do that. Even if you define your own mutable generic Tuple, it will failed since the name of the property must match the name of the column:
SqlQuery(String, Object[]): Creates a raw SQL query that will
return elements of the given generic type. The type can be any type
that has properties that match the names of the columns returned from
the query, or can be a simple primitive type.
I think the best you can do is creating your own generic method for querying the database via classic Command and ExecuteReader pattern. Untested, but you get the idea:
public static IEnumerable<Tuple<T>> SqlQuery<T>(this DbContext context, string sql)
{
using(var connection = new SqlConnection(context.Database.Connection.ConnectionString))
using (var command = new SqlCommand(sql, connection))
{
var reader = command.ExecuteReader();
while (reader.NextResult())
{
yield return new Tuple<T>((T)reader[0]);
}
}
}
public static IEnumerable<Tuple<T1, T2>> SqlQuery<T1, T2>(this DbContext context, string sql)
{
using (var connection = new SqlConnection(context.Database.Connection.ConnectionString))
using (var command = new SqlCommand(sql, connection))
{
var reader = command.ExecuteReader();
while (reader.NextResult())
{
yield return new Tuple<T1, T2>((T1)reader[0], (T2)reader[1]);
}
}
}
I want one method that can query my entire RavenDB database.
My method signature looks like this:
public static DataTable GetData(string className, int amount, string orderByProperty, string filterByProperty, string filterByOperator, string filterCompare)
I figured I can accomplish all of the above with a dynamic LuceneQuery.
session.Advanced.LuceneQuery<dynamic>();
The problem is: Since I'm using dynamic in the type given, how do I ensure that the query only includes the types matching the className?
I'm looking for something like .WhereType(className) or .Where("type: " + className).
Solution
This returns the results of the correct type:
var type = Type.GetType("Business.Data.DTO." + className);
var tagName = RavenDb.GetTypeTagName(type);
using (var session = RavenDb.OpenSession())
{
var result = session.Advanced
.LuceneQuery<object, RavenDocumentsByEntityName>()
.WhereEquals("Tag", tagName)
.ToList();
}
Note, it is not possible to add additional "WhereEquals" or other filters to this. This is because nothing specific to that document type is included in the "RavenDocumentByEntityName" index.
This means that this solution cannot be used for what I wanted to accomplish.
What I ended up doing
Although it doesn't fulfill my requirement completely, this is what I ended up doing:
public static List<T> GetData<T>(DataQuery query)
{
using (var session = RavenDb.OpenSession())
{
var result = session.Advanced.LuceneQuery<T>();
if (!string.IsNullOrEmpty(query.FilterByProperty))
{
if (query.FilterByOperator == "=")
{
result = result.WhereEquals(query.FilterByProperty, query.FilterCompare);
}
else if (query.FilterByOperator == "StartsWith")
{
result = result.WhereStartsWith(query.FilterByProperty, query.FilterCompare);
}
else if (query.FilterByOperator == "EndsWith")
{
result = result.WhereEndsWith(query.FilterByProperty, query.FilterCompare);
}
}
if (!string.IsNullOrEmpty(query.OrderByProperty))
{
if (query.Descending)
{
result = result.OrderBy(query.OrderByProperty);
}
else
{
result = result.OrderByDescending(query.OrderByProperty);
}
}
result = result.Skip(query.Skip).Take(query.Amount);
return result.ToList();
}
}
Although this is most certainly an anti-pattern, it's a neat way to just look at some data, if that's what you want. It's called very easily like this:
DataQuery query = new DataQuery
{
Amount = int.Parse(txtAmount.Text),
Skip = 0,
FilterByProperty = ddlFilterBy.SelectedValue,
FilterByOperator = ddlOperator.SelectedValue,
FilterCompare = txtCompare.Text,
OrderByProperty = ddlOrderBy.SelectedValue,
Descending = chkDescending.Checked
};
grdData.DataSource = DataService.GetData<Server>(query);
grdData.DataBind();
"Server" is one of the classes/document types I'm working with, so the downside, where it isn't completely dynamic, is that I would have to define a call like that for each type.
I strongly suggest you don't go down this road. You are essentially attempting to hide the RavenDB Session object, which is very powerful and intended to be used directly.
Just looking at the signature of the method you want to create, the parameters are all very restrictive and make a lot of assumptions that might not be true for the data you're working on. And the return type - why would you return a DataTable? Maybe return an object or a dynamic, but nothing in Raven is structured in tables, so DataTable is a bad idea.
To answer the specific question, the type name comes from the Raven-Entity-Name metadata, which you would need to build an index over. This happens automatically when you index using the from docs.YourEntity syntax in an index. Raven does this behind the scenes when you use a dynamic index such as .Query<YourEntity> or .Advanced.LuceneQuery<YourEntity>.
Still, you shouldn't do this.
I need to figure out if it is possible to dynamically build a query with LINQ, dynamically selecting the table in which to perform the query.
This is an example of what I would do:
//Not working,just for example
public List<dynamic> _getGenericList(String tableName)
{
var l = from a in db.//I need to use here tableName
select a;
return l.ToList<dynamic>();
}
Is there a way to make this possible?
If the query is this simple you can dynamically create a standard sql statement and execute it, this is the most simplest way without using processor heavy reflection and complex code?
var query = "SELECT * FROM " + tableName;
var res = context.ExecuteQuery<dynamic>(query).ToList();
I've found a way to do it, but I'm not sure if I'd use this code. If you have a DataContext that contains two tables:
PrimaryTable
ID,
FirstValue,
SecondValue
SecondaryTable
ID,
FirstSecondaryValue
You could use the following DataHelper class:
class DataHelper
{
public MyDatabaseDataContext db = new MyDatabaseDataContext();
List<dynamic> GetDynamicList<T>() where T : class
{
System.Data.Linq.Table<T> table = db.GetTable<T>();
var result = from a in table select a;
return result.ToList<dynamic>();
}
public List<dynamic> GetWhatIWant(string tableName)
{
Type myClass = Type.GetType("DynamicLinqToSql." + tableName);
MethodInfo method = typeof(DataHelper).GetMethod("GetDynamicList", BindingFlags.NonPublic | BindingFlags.Instance);
method = method.MakeGenericMethod(myClass);
return (List<dynamic>)method.Invoke(this, null);
}
}
Then you can create an instance of your DataHelper and call the GetWhatIWant method, passing in the table name.
var dataHelper = new DataHelper();
List<dynamic> myFirstList = dataHelper.GetWhatIWant("PrimaryTable");
for (int i = 0; i < 5 && i < myFirstList.Count; i++)
{
System.Console.WriteLine(String.Format("{0} - {1}", myFirstList[i].FirstValue.ToString(), myFirstList[i].SecondValue.ToString()));
}
List<dynamic> mySecondList = dataHelper.GetWhatIWant("SecondaryTable");
for (int i = 0; i < 5 && i < mySecondList.Count; i++)
{
System.Console.WriteLine(mySecondList[i].FirstSecondaryValue.ToString());
}
System.Console.ReadKey();
I know this is old, but if you are here looking for answers like I was, then maybe this will help. I'm using a .NET ObjectContext directly instead of a DataContext data source. If you are using the DataContext version then you can simply (I hope) use queryResults = myGlobalContext.ExecuteQuery<dbGenericData>(query).ToList(); instead and I'm pretty sure it will work the same way.
Your tables will be a lot easier to work with if you have standards in naming and design like
the ID field for the table is always X type (INT, GUID, etc)
the ID field is always named tableNameID, the 'table name' with ID tagged on.
etc,
This will allow you to easily build the ID field by simply appending the 'ID' string onto the table name and will allow you to use a reliable CAST, if needed.
Speaking of CAST you will notice one in the query string. You will need to modify the use of the SQL string using CAST, changing field lengths like my nvarChar(50) example, etc, to overcome getting various TYPES of data from your database.
Final note: In the query string you will see I use the 'AS' key word to cast the DB field to a new name. I cast the 'tableIDField' into the name 'id' and I cast the 'requestedField' into the name 'dbData'. This allows the system to match up the renamed fields from the DB into the STRUCT object container we dump the data into. This allows you to construct generic containers to hold the data returned without having to worry about matching up with the DB field names.
I'm not a guru at this stuff, but I hope this helps somebody out.
private void testMethod(string requestedField, string tableName)
{
var tableIDField = tableName + "ID";
var query = "select " + tableIDField + " as id, CAST(" + requestedField + "as nvarchar(50)) as dbData from " + tableName;
List<dbGenericData> queryResults = null;
try
{
queryResults = myGlobalContext.ExecuteStoreQuery<dbGenericData>(query).ToList();
}
catch (Exception ex)
{
//Simply ignore any exceptions.
//These will need examined to determine best solution to unexpected results.
}
}
private struct dbGenericData
{
public dbGenericData(int id, string dbData)
{
this = new dbGenericData();
ID = id;
DBData = dbData;
}
public int ID { get; set; }
public string DBData { get; set; }
}
you can Generic Method and use db.Set<T> that return a DbSet Based on T
var esql = "select t from TypeName as t"
var q = db.CreateQuery(esql);
Use entity sql for linq to sql, http://esql.codeplex.com