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export file with asp.net

This project is an ASP.Net Api project with Angular. What I'm trying to do is export data from a database table and into an excel file. So far, I've managed to export all the table data into an excel file, but struggle to select 2 or 3 fields in the table to export.
[HttpGet("download")]
public IActionResult DownloadExcel(string field)
{
string dbFileName = "DbTableName.xlsx";
FileInfo file = new FileInfo(dbFileName);
byte[] fileContents;
var stream = new MemoryStream();
using (ExcelPackage package = new ExcelPackage(file))
{
IList<UserTable> userList = _context.UserTable.ToList();
ExcelWorksheet worksheet = package.Workbook.Worksheets.Add("DbTableName");
int totalUserRows = userList.Count();
}
return File(fileContents, fileType, dbFileName);
}

There's no need to write so many if ... else if ... else if ... else if ... to get the related field names.
A nicer way is to
Use a field list (IList<string>)as a parameter.
And then generate a required field list by intersect.
Finally, we could use reflection to retrieve all the related values.
Implementation
public IActionResult DownloadExcel(IList<string> fields)
{
// get the required field list
var userType = typeof(UserTable);
fields = userType.GetProperties().Select(p => p.Name).Intersect(fields).ToList();
if(fields.Count == 0){ return BadRequest(); }
using (ExcelPackage package = new ExcelPackage())
{
IList<UserTable> userList = _context.UserTable.ToList();
ExcelWorksheet worksheet = package.Workbook.Worksheets.Add("DbTableName");
// generate header line
for(var i= 0; i< fields.Count; i++ ){
var fieldName = fields[i];
var pi= userType.GetProperty(fieldName);
var displayName = pi.GetCustomAttribute<DisplayNameAttribute>()?.DisplayName;
worksheet.Cells[1,i+1].Value = string.IsNullOrEmpty(displayName ) ? fieldName : displayName ;
}
// generate row lines
int totalUserRows = userList.Count();
for(var r=0; r< userList.Count(); r++){
var row = userList[r];
for(var c=0 ; c< fields.Count;c++){
var fieldName = fields[c];
var pi = userType.GetProperty(fieldName);
// because the first row is header
worksheet.Cells[r+2, c+1].Value = pi.GetValue(row);
}
}
var stream = new MemoryStream(package.GetAsByteArray());
return new FileStreamResult(stream,"application/vnd.openxmlformats-officedocument.spreadsheetml.sheet");
}
}
You could configure the display name using the DsiplayNameAttribute:
public class UserTable
{
public int Id{get;set;}
[DisplayName("First Name")]
public string fName { get; set; }
[DisplayName("Last Name")]
public string lName { get; set; }
[DisplayName("Gender")]
public string gender { get; set; }
}
It's possible to add any properties as you like without hard-coding in your DownloadExcel method.
Demo :
passing a field list fields[0]=fName&fields[1]=lName&fields[2]=Non-Exist will generate an excel as below:
[Update]
To export all the fields, we could assume the client will not pass a fields parameter. That means when the fields is null or if the fields.Count==0, we'll export all the fields:
[HttpGet("download")]
public IActionResult DownloadExcel(IList<string> fields)
{
// get the required field list
var userType = typeof(UserTable);
var pis= userType.GetProperties().Select(p => p.Name);
if(fields?.Count >0){
fields = pis.Intersect(fields).ToList();
} else{
fields = pis.ToList();
}
using (ExcelPackage package = new ExcelPackage()){
....
}
}

if you want to use the datatable then we can define which you need to select from the datatable in this way
string[] selectedColumns = new[] { "Column1","Column2"};
DataTable dt= new DataView(fromDataTable).ToTable(false, selectedColumns);
or else if you wanna you list then you can use linq for selection of particular columns
var xyz = from a in prod.Categories
where a.CatName.EndsWith("A")
select new { CatName=a.CatName, CatID=a.CatID, CatQty = a.CatQty};

How can I return result of string Kusto Query from c#

var kusto = string.Format("let MyData = CompanyMydata" +
" | where ID == 'Z123' | top 1 by dateTimeUtc desc");
var reader = client.ExecuteQuery(kusto);
while (reader.Read())
{
//how can i return coming result as list of string or json string?
}
In while loop I can able to return single column value one by one by using
string state = reader.GetString(1); but i want to return complete result instead of one by one column value.
so that i can do JsonConvert.DeserializeObject<T>(resultString); to specific class.

assuming you're using the client libraries mentioned here, you should be able to do something like the following:
static void Main(string[] args)
{
var kcsb = new KustoConnectionStringBuilder("https://help.kusto.windows.net").WithAadUserPromptAuthentication();
var databaseName = "Samples";
using (var queryProvider = KustoClientFactory.CreateCslQueryProvider(kcsb))
{
var clientRequestProperties = new ClientRequestProperties() { ClientRequestId = "Sample;" + Guid.NewGuid() };
var query = "StormEvents | summarize count(), max(EndTime) by State";
var result = queryProvider.ExecuteQuery<MyType>( // focus on this part
databaseName,
query,
clientRequestProperties)
.ToList();
foreach (var row in result)
{
Console.WriteLine($"State = {row.State}, Count = {row.Count}, MaxEndTime = {row.MaxEndTime}");
}
}
}
class MyType
{
public string State;
public long Count;
public DateTime MaxEndTime;
}

Dapper query with dynamic list of filters

I have a c# mvc app using Dapper. There is a list table page which has several optional filters (as well as paging). A user can select (or not) any of several (about 8 right now but could grow) filters, each with a drop down for a from value and to value. So, for example, a user could select category "price" and filter from value "$100" to value "$200". However, I don't know how many categories the user is filtering on before hand and not all of the filter categories are the same type (some int, some decimal/double, some DateTime, though they all come in as string on FilterRange).
I'm trying to build a (relatively) simple yet sustainable Dapper query for this. So far I have this:
public List<PropertySale> GetSales(List<FilterRange> filterRanges, int skip = 0, int take = 0)
{
var skipTake = " order by 1 ASC OFFSET #skip ROWS";
if (take > 0)
skipTake += " FETCH NEXT #take";
var ranges = " WHERE 1 = 1 ";
for(var i = 0; i < filterRanges.Count; i++)
{
ranges += " AND #filterRanges[i].columnName BETWEEN #filterRanges[i].fromValue AND #filterRanges[i].toValue ";
}
using (var conn = OpenConnection())
{
string query = #"Select * from Sales "
+ ranges
+ skipTake;
return conn.Query<Sale>(query, new { filterRanges, skip, take }).AsList();
}
}
I Keep getting an error saying "... filterRanges cannot be used as a parameter value"
Is it possible to even do this in Dapper? All of the IEnumerable examples I see are where in _ which doesn't fit this situation. Any help is appreciated.

You can use DynamicParameters class for generic fields.
Dictionary<string, object> Filters = new Dictionary<string, object>();
Filters.Add("UserName", "admin");
Filters.Add("Email", "admin#admin.com");
var builder = new SqlBuilder();
var select = builder.AddTemplate("select * from SomeTable /**where**/");
var parameter = new DynamicParameters();
foreach (var filter in Filters)
{
parameter.Add(filter.Key, filter.Value);
builder.Where($"{filter.Key} = #{filter.Key}");
}
var searchResult = appCon.Query<ApplicationUser>(select.RawSql, parameter);

You can use a list of dynamic column values but you cannot do this also for the column name other than using string format which can cause a SQL injection.
You have to validate the column names from the list in order to be sure that they really exist before using them in a SQL query.
This is how you can use the list of filterRanges dynamically :
const string sqlTemplate = "SELECT /**select**/ FROM Sale /**where**/ /**orderby**/";
var sqlBuilder = new SqlBuilder();
var template = sqlBuilder.AddTemplate(sqlTemplate);
sqlBuilder.Select("*");
for (var i = 0; i < filterRanges.Count; i++)
{
sqlBuilder.Where($"{filterRanges[i].ColumnName} = #columnValue", new { columnValue = filterRanges[i].FromValue });
}
using (var conn = OpenConnection())
{
return conn.Query<Sale>(template.RawSql, template.Parameters).AsList();
}

You can easily create that dynamic condition using DapperQueryBuilder:
using (var conn = OpenConnection())
{
var query = conn.QueryBuilder($#"
SELECT *
FROM Sales
/**where**/
order by 1 ASC
OFFSET {skip} ROWS FETCH NEXT {take}
");
foreach (var filter in filterRanges)
query.Where($#"{filter.ColumnName:raw} BETWEEN
{filter.FromValue.Value} AND {filter.ToValue.Value}");
return conn.Query<Sale>(query, new { filterRanges, skip, take }).AsList();
}
Or without the magic word /**where**/:
using (var conn = OpenConnection())
{
var query = conn.QueryBuilder($#"
SELECT *
FROM Sales
WHERE 1=1
");
foreach (var filter in filterRanges)
query.Append($#"{filter.ColumnName:raw} BETWEEN
{filter.FromValue.Value} AND {filter.ToValue.Value}");
query.Append($"order by 1 ASC OFFSET {skip} ROWS FETCH NEXT {take}");
return conn.Query<Sale>(query, new { filterRanges, skip, take }).AsList();
}
The output is fully parametrized SQL, even though it looks like we're doing plain string concatenation.
Disclaimer: I'm one of the authors of this library

I was able to find a solution for this. The key was to convert the List to a Dictionary. I created a private method:
private Dictionary<string, object> CreateParametersDictionary(List<FilterRange> filters, int skip = 0, int take = 0)
{
var dict = new Dictionary<string, object>()
{
{ "#skip", skip },
{ "#take", take },
};
for (var i = 0; i < filters.Count; i++)
{
dict.Add($"column_{i}", filters[i].Filter.Description);
// some logic here which determines how you parse
// I used a switch, not shown here for brevity
dict.Add($"#fromVal_{i}", int.Parse(filters[i].FromValue.Value));
dict.Add($"#toVal_{i}", int.Parse(filters[i].ToValue.Value));
}
return dict;
}
Then to build my query,
var ranges = " WHERE 1 = 1 ";
for(var i = 0; i < filterRanges.Count; i++)
ranges += $" AND {filter[$"column_{i}"]} BETWEEN #fromVal_{i} AND #toVal_{i} ";
Special note: Be very careful here as the column name is not a parameter and you could open your self up to injection attacks (as #Popa noted in his answer). In my case those values come from an enum class and not from user in put so I am safe.
The rest is pretty straight forwared:
using (var conn = OpenConnection())
{
string query = #"Select * from Sales "
+ ranges
+ skipTake;
return conn.Query<Sale>(query, filter).AsList();
}

How to add object to database from an IEnumerable collection?

I have a collection of ienumerable entities to be added to the database but it seems some conversion is needed. Can anyone point me in the right direction?
bool InsertDetails(DataTable detailTable, string fileName)
{
using (SunseapEBTContext context = new SunseapEBTContext())
{
if (InsertMaster(fileName))//if creating master record successful
{
int masterId = GetSPReadingM(m => m.FileName == fileName).SPReadingMasterId; //get MasterID of file uploaded
var details = detailTable.AsEnumerable().Select(row => new LeasingSPReadingDetailEntity()//new entity from datatable
{
//SPReadingId = row.Field<long>("ProductID"),
SPReadingMasterId = masterId,
BillCycleYear = int.Parse(row.Field<int>("Bill Cycle").ToString().Substring(0, 4)),
BillCycleMonth = byte.Parse(row.Field<byte>("Bill Cycle").ToString().Substring(4))
});
foreach(IEnumerable<LeasingSPReadingDetailEntity> detail in details)
{
context.LeasingSPReadingDetailEntities.AddObject(detail);
}
context.SaveChanges();
}
return true;
}
}
In the foreach loop, exception is thrown
CS1503 Argument 1: cannot convert from 'System.Collections.Generic.IEnumerable' to 'SunseapEBT.Domain.BillingModule.LeasingContract.Entity.LeasingSPReadingDetailEntity'
LeasingSPReadingDetailEntity class:
public class LeasingSPReadingDetailEntity
{
public long SPReadingId { get; set; }
public int SPReadingMasterId { get; set; }
public int BillCycleYear { get; set; }
public byte BillCycleMonth { get; set; }
}
More info:
A file which contains details is uploaded and will create a master record in one table. The details in the file are to be added to a separate table with the auto generated masterId from the first table. The issue is not being able to add the details into the database.
Edit:
I have found out why there was an error. The error was because of the contents of the file. Some rows had no values entered and the last row did not follow the format for the rest of the rows as it shows the total number of rows. Thanks all for the help!

#slawekwin comment is the answer. But I think there is a better solution, because it seems like your code is iterating 2x: 1st to generate new Enumerable (wasting memory), 2nd to add the object to context.
Might as well add the object directly when you iterate each rows.
foreach(var row in detailTable.AsEnumerable())
{
context.LeasingSPReadingDetailEntities.AddObject(
new LeasingSPReadingDetailEntity()//new entity from datatable
{
//SPReadingId = row.Field<long>("ProductID"),
SPReadingMasterId = masterId,
BillCycleYear = int.Parse(row.Field<string>("Bill Cycle").Substring(0, 4)),
BillCycleMonth = byte.Parse(row.Field<string>("Bill Cycle").Substring(4)),
AccountNumber = row.Field<string>("Account No."),
PeriodStart = row.Field<DateTime>("Period Start"),
PeriodEnd = row.Field<DateTime>("Period End"),
TownCouncil = row.Field<string>("Customer Name"),
Service = row.Field<string>("Service Type"),
Adjustment = row.Field<string>("Adjustment"),
Block = row.Field<string>("Blk"),
AddressLine1 = row.Field<string>("Adress Line 1"),
AddressLine2 = row.Field<string>("Adress Line 2"),
AddressLine3 = row.Field<string>("Postal Code"),
Usage = row.Field<decimal>("Usage"),
Rate = row.Field<decimal>("Rate"),
Amount = row.Field<decimal>("Amount")
}
);
}
--- EDIT ---
I am not sure, but I can guess that "Bill Cycle" field is neither int nor byte. Therefore, you should have retrieved it as string, then parse it to your new object. This is the part the I changed:
BillCycleYear = int.Parse(row.Field<string>("Bill Cycle").Substring(0, 4)),
BillCycleMonth = byte.Parse(row.Field<string>("Bill Cycle").Substring(4)),

You can change the problematic foreach loop to either of the below ones. I would prefer the first one as it is less verbose.
foreach(var detail in details)
{
context.LeasingSPReadingDetailEntities.AddObject(detail);
}
OR
foreach(LeasingSPReadingDetailEntity detail in details)
{
context.LeasingSPReadingDetailEntities.AddObject(detail);
}
If you look at the syntax of foreach loop, the very first construct variableType is type of the element being stored in the collection (LeasingSPReadingDetailEntity in your case) and NOT the type of the collection. You did the later which is why you are getting the invalid cast error.
foreach(variableType currentElementBeingIterated in collection){
//code block to operate on currentElement
}

Change it to List then add the item.
var details = detailTable.AsEnumerable().Select(row => new LeasingSPReadingDetailEntity()//new entity from datatable
{
SPReadingId = row.Field<long>("ProductID"),
SPReadingMasterId = masterId,
BillCycleYear = int.Parse(row.Field<int>("Bill Cycle").ToString().Substring(0, 4)),
BillCycleMonth = byte.Parse(row.Field<byte>("Bill Cycle").ToString().Substring(4)),
}).ToList();
foreach(var detail in details)
{
context.LeasingSPReadingDetailEntities.Add(detail);
}
or better still:
var details = detailTable.AsEnumerable().Select(row => new LeasingSPReadingDetailEntity()//new entity from datatable
{
SPReadingId = row.Field<long>("ProductID"),
SPReadingMasterId = masterId,
BillCycleYear = int.Parse(row.Field<int>("Bill Cycle").ToString().Substring(0, 4)),
BillCycleMonth = byte.Parse(row.Field<byte>("Bill Cycle").ToString().Substring(4)),
}).ToList();
context.LeasingSPReadingDetailEntities.AddRange(details);

Dynamic Array to MS SQL Database

private void getRRvalue(string DELRRNO)
{
try {
DBSFCDataContext SFC = new DBSFCDataContext();
var query = (from i in SFC.POP10500s where i.POPRCTNM == DELRRNO select new { PONO = i.PONUMBER, DATEREC = i.DATERECD, VENDID = i.VENDORID, ITEMCODE = i.ITEMNMBR, QTYBAGS = i.QTYBAGS, QTYSHIP = i.QTYSHPPD, DEPT = i.TRXLOCTN });
foreach (var r in query)
{
string[] row = {
DELRRNO,
r.PONO,
Convert.ToDateTime(r.DATEREC).ToString(),
r.VENDID,
r.ITEMCODE,
r.QTYBAGS.ToString(),
r.QTYSHIP.ToString(),
r.DEPT
};
//glbVariables.getRRNO = ;
//glbVariables.getPONO = ;
//glbVariables.getRRdateRec = ;
//glbVariables.getVendID = ;
//glbVariables.getItemNO = ;
//glbVariables.getQtyBags = ;
//glbVariables.getQtyShipped = ;
//glbVariables.getLocnCode = ;
}
SFC.Connection.Close();
}
catch (Exception ex)
{ MessageBox.Show(ex.Message.ToString()); }
}
I'm new to C#.NET and I was just thinking if I could use a dynamic array like for this code above do I need to declare a global array like this --> "public static string[] row;" so I can use this array string in another form by calling it with the data that I have stored from this function, could this happen in c#?
I need help here please anyone that is good at arrays in c#...

To get you desired results, you will have to do little more work. I explain your solution using List.
First create a class for your one query result:
public class OneRowData
{
public string DELRRNO;
public string PONO;
public string DATEREC;
public string VENDID;
public string ITEMCODE;
public string QTYBAGS;
public string QTYSHIP;
public string DEPT;
}
In your given code, create a List of OneRowData type and make it public static to access it from outside the class as well:
public static List<OneRowData> QueryResults = new List<OneRowData>();
Now in your foreach loop, create an object of OneRowData, assing values to it and add it to the List:
foreach (var r in query)
{
OneRowData Obj = new OneRowData();
//assing values to them
Obj.DATEREC = Convert.ToDateTime(r.DATEREC).ToString();
Obj.DELRRNO = DELRRNO;
Obj.DEPT = r.DEPT;
Obj.ITEMCODE = r.ITEMCODE;
Obj.PONO = r.PONO;
Obj.QTYBAGS = r.QTYBAGS.ToString();
Obj.QTYSHIP = r.QTYSHIP.ToString();
Obj.VENDID = r.VENDID;
//then add the object to your list
QueryResults.Add(Obj);
}
Now you can simply call your List any where and fetch your data like this:
foreach (OneRowData Row in QueryResults)
{
//Row.DATEREC
//Row.DELRRNO
//call them like this and use as you need
}