Is there a way of looping through the properties of the underlining result of the linq statement when the linq statement contains no elements?
I would like to create a DataTable and add the individual properties as columns, but it seems this can only be done when the linq statement contains items. Please see my current code below
private static void GetProperties<T>(IEnumerable<T> query)
{
DataTable dt = new DataTable();
PropertyInfo[] queryInfo = null;
foreach (var item in query)
{
if (queryInfo == null)
{
queryInfo = item.GetType().GetProperties();
foreach (var info in queryInfo)
{
dt.Columns.Add(info.Name);
}
}
DataRow dr = dt.NewRow();
foreach (PropertyInfo pi in queryInfo)
{
dr[pi.Name] = pi.GetValue(item, null) ?? DBNull.Value;
}
dt.Rows.Add(dr);
}
}
Desired code, or something similar:
private static void GetProperties<T>(IEnumerable<T> query)
{
DataTable dt = new DataTable();
PropertyInfo[] queryInfo = null;
queryInfo = query.FirstOrDefault().GetType().GetProperties();
foreach (var info in queryInfo)
{
dt.Columns.Add(info.Name);
}
foreach (var item in query)
{
DataRow dr = dt.NewRow();
foreach (PropertyInfo pi in queryInfo)
{
dr[pi.Name] = pi.GetValue(item, null) ?? DBNull.Value;
}
dt.Rows.Add(dr);
}
}
I would always like the DataTable to contain the columns, even if the linq statement contains no items.
I am open to any suggestions.
Thanks.
I suspect all you're looking for it:
PropertyInfo[] queryInfo = typeof(T).GetProperties();
In other words, get the properties from the generic type argument rather than for a particular instance of that type.
Related
I am currently having a performance problem with the following query written in NHibernate. I am trying to transform the data I queried into DTO's. With this complex structure I cannot use QueryOver to transform the entities. On the other side Linq provider is so useful but it takes ~10 seconds to load and transform ~6000 entities with each 30 child items. It creates an SQL query with left outer join. Are there any other ways to write this query with a better approach?
var Entities = session.Query<crmEntity>()
.Where(x => x.EntityType.ID == EntityType)
.Select(entity => new EntityDTO()
{
ID = entity.ID,
EntityType = entity.EntityType.ID,
InstanceID = entity.Instance.ID,
Values = entity.Values.Select(
value => new CustomFieldValueDTO()
{
ID = value.ID,
FieldID = value.Field.ID,
Value = value.Value
}).ToList<CustomFieldValueDTO>()
}).ToList();
Here is my solution. if there is any other better way, I am completely open to it:
session.CreateQuery(#"select vals.ID,
vals.Field.ID,
vals.Value,
ent.ID
from crmEntity ent inner join ent.Values vals
with vals.Value IS NOT NULL
where ent.EntityType.ID=:eID and ent.Instance.ID=:instanceID order by ent.ID")
.SetGuid("instanceID", InstanceID)
.SetGuid("eID", EntityType)
.SetResultTransformer(new EntityListTransformer()).Future<ReadOnlyEntityDTO>();
And this is my custom result transformer to get the same hierarchy like my linq query
public class EntityListTransformer : IResultTransformer
{
private List<ReadOnlyEntityDTO> list;
private ReadOnlyEntityDTO lastEntity;
private Guid instanceID;
public EntityListTransformer()
{
list = new List<ReadOnlyEntityDTO>();
lastEntity = new ReadOnlyEntityDTO();
}
public System.Collections.IList TransformList(System.Collections.IList collection)
{
return list;
}
public object TransformTuple(object[] tuple, string[] aliases)
{
string ValueID = tuple[0].ToString();
string FieldID = tuple[1].ToString();
string Value = (string)tuple[2];
string EntityID = tuple[3].ToString();
if (lastEntity.ID != EntityID)
{
if (lastEntity.ID != null)
{
list.Add(lastEntity);
}
lastEntity = new ReadOnlyEntityDTO()
{
ID = EntityID
};
}
lastEntity.Values.Add(new ReadOnlyCustomFieldValueDTO()
{
FieldID = FieldID,
ID = ValueID,
Value = Value
});
return tuple;
}
}
I am using RadControls for WinForms 2011 Q3
The datasource for a RadGridView is dynamically generated based on users' input/selection
Everytime when a datasource is generated, I will call SetDatasource2KeyValuesGrid()
What I expect to see is columns generated and values filled in gridview.
However what I see is columns generated but no value filled even though the number of rows in gridview match the number of items in its datasource(keyValuesList)
I must have missed something simple. Please help. thanks
Edit:
I create a DataTable from the list keyValueList, and then assign it to DataSource, then it works
Just wonder if there's a better way. thanks
private void CreateTableSetDatasource(List<FeedKeyValueOneSet>) keyValueList)
{
if(keyValueList==null) return;
var table = new DataTable();
table.Columns.Add("Check");
foreach (var feedKeyValueOneSet in keyValueList)
{
var oneset = feedKeyValueOneSet.KeyValueOneSet;
foreach (var oneKey in oneset)
{
table.Columns.Add(oneKey.key);
}
break;
}
foreach (var feedKeyValueOneSet in keyValueList)
{
var oneset = feedKeyValueOneSet.KeyValueOneSet;
var numOfCol = oneset.Length + 1;
var obj = new object[numOfCol];
obj[0] = "false";
int idx = 1;
foreach (var oneKey in oneset)
{
obj[idx] = oneKey.value;
idx++;
}
table.Rows.Add(obj);
}
radGridKeyValues.DataSource = table;
}
private void SetDatasource2KeyValuesGrid()
{
if (radGridKeyValues.Columns != null) radGridKeyValues.Columns.Clear();
radGridKeyValues.AutoGenerateColumns = false;
radGridKeyValues.EnableFiltering = false;
radGridKeyValues.ShowFilteringRow = false;
radGridKeyValues.ShowHeaderCellButtons = false;
radGridKeyValues.AllowDragToGroup = false;
radGridKeyValues.AllowAddNewRow = false;
radGridKeyValues.EnableGrouping = false;
var keyValueList = (List<FeedKeyValueOneSet>)TimeSeries.FeedValuesCache[m_strFeedName + "_KEYVALUES"];
if(keyValueList==null) return;
GridViewDataColumn checkBoxColumn = new GridViewCheckBoxColumn("columnState", "columnState");
checkBoxColumn.HeaderText = string.Empty;
if (radGridKeyValues.Columns != null) radGridKeyValues.Columns.Add(checkBoxColumn);
foreach (var feedKeyValueOneSet in keyValueList)
{
var oneset = feedKeyValueOneSet.KeyValueOneSet;
foreach (var oneKey in oneset)
{
var textboxCol = new GridViewTextBoxColumn(oneKey.key, oneKey.key);
textboxCol.Width = 150;
textboxCol.ReadOnly = true;
if (radGridKeyValues.Columns != null) radGridKeyValues.Columns.Add(textboxCol);
}
break;
}
radGridKeyValues.DataSource = keyValueList;
}
public class FeedKeyValueOneSet
{
public FeedFieldValues[] KeyValueOneSet;
}
public class FeedFieldValues
{
public string key { get; set; }
public string value { get; set; }
}
I create a DataTable from the list keyValueList, and then assign it to DataSource, then it works
see code in edit to the question
When I run this line of code
queryCompanies = (DbSet)queryCompanies.Include(path);
from this method:
public Company GetCompanyById(int companyId)
{
List<string> includePaths = new List<string>();
includePaths.Add("Addresses");
includePaths.Add("Users");
Company company = null;
using (Entities dbContext = new Entities())
{
var queryCompanies = dbContext.Companies;
if (includePaths != null)
{
foreach (string path in includePaths)
queryCompanies = (DbSet<Company>)queryCompanies.Include(path);
}
company = (from c in queryCompanies
where c.Id.Equals(companyId)
select c).FirstOrDefault<Company>();
}
return company;
}
I get this error:
Unable to cast object of type 'System.Data.Entity.Infrastructure.DbQuery1[ClassLibrary1.Company]' to type 'System.Data.Entity.DbSet1[ClassLibrary1.Company]'.
At compilation I have no error. In EF 4.0 this code runs correct using instead of DbSet<>, ObjectQuery<>.
I am a beginner in EF 4.1 so any suggestion will be useful.
Thanks.
Try this
public Company GetCompanyById(int companyId)
{
List<string> includePaths = new List<string>();
includePaths.Add("Addresses");
includePaths.Add("Users");
Company company = null;
using (Entities dbContext = new Entities())
{
var queryCompanies = dbContext.Companies.AsQueryable();
if (includePaths != null)
{
foreach (string path in includePaths)
queryCompanies = queryCompanies.Include(path);
}
company = (from c in queryCompanies
where c.Id.Equals(companyId)
select c).FirstOrDefault<Company>();
}
return company;
}
DbSet inherits from DbQuery, so the compiler doesn't complain since the cast could be valid. Apparently, what DbSet<T>.Include returns is not a DbSet<T> and the cast fails at runtime.
However, you do not need to cast; calling FirstOrDefault will work on DbQuery<T>.
I write a generic include checker method. This is not good now but it is work. I will refactor this. Maybe it meets your needs.
List<TEntityType> GetEntityListTemplate(Expression<Func<TEntityType, bool>> expression = null)
{
List<TEntityType> entityList;
DbQuery<TEntityType> query = null;
Type entityType = typeof(TEntityType);
PropertyInfo[] properties = entityType.GetProperties();
using (DatabaseContext database = new DatabaseContext())
{
database.Database.Connection.Open();
foreach (PropertyInfo property in properties)
{
if (property.PropertyType.FullName.Contains("Your.Identifier.Namespace"))
{
if (query == null)
{
query = database.Set<TEntityType>().Include(property.Name);
}
else
{
query = query.Include(property.Name);
}
}
}
if (query == null)
{
if (expression == null)
{
entityList = database.Set<TEntityType>().ToList();
}
else
{
entityList = database.Set<TEntityType>().Where(expression).ToList();
}
}
else //(query!=null)
{
if (expression == null)
{
entityList = query.ToList();
}
else
{
entityList = query.Where(expression).ToList();
}
}
}
return entityList;
}
I am getting the result from linq query as var(IEnumrable<'T'> anonymous type<'string,int>')
i want the result to be in the datatable or dataset.
I found two sample for that issue;
Sample I:
I created a public method called LINQToDataTable as following:
public DataTable LINQToDataTable<T>(IEnumerable<T> varlist)
{
DataTable dtReturn = new DataTable();
// column names
PropertyInfo[] oProps = null;
if (varlist == null) return dtReturn;
foreach (T rec in varlist)
{
// Use reflection to get property names, to create table, Only first time, others
will follow
if (oProps == null)
{
oProps = ((Type)rec.GetType()).GetProperties();
foreach (PropertyInfo pi in oProps)
{
Type colType = pi.PropertyType;
if ((colType.IsGenericType) && (colType.GetGenericTypeDefinition()
==typeof(Nullable<>)))
{
colType = colType.GetGenericArguments()[0];
}
dtReturn.Columns.Add(new DataColumn(pi.Name, colType));
}
}
DataRow dr = dtReturn.NewRow();
foreach (PropertyInfo pi in oProps)
{
dr[pi.Name] = pi.GetValue(rec, null) == null ?DBNull.Value :pi.GetValue
(rec,null);
}
dtReturn.Rows.Add(dr);
}
return dtReturn;
}
Sample II
Here is my second method:
public DataTable ToDataTable(System.Data.Linq.DataContext ctx, object query)
{
if (query == null)
{
throw new ArgumentNullException("query");
}
IDbCommand cmd = ctx.GetCommand(query as IQueryable);
SqlDataAdapter adapter = new SqlDataAdapter();
adapter.SelectCommand = (SqlCommand)cmd;
DataTable dt = new DataTable("sd");
try
{
cmd.Connection.Open();
adapter.FillSchema(dt, SchemaType.Source);
adapter.Fill(dt);
}
finally
{
cmd.Connection.Close();
}
return dt;
}
I am using the following code to get a record from my database table tblDatabases. I then populate Controls on a Form based on the value. I have used some functions to get the values needed for displaying in a text box (e.g. the display value is different than the value.
The DetailData is an object in my base form class. Initially I just got the record from the table as is and I was able to cast the DetailData to the tblDatabases and use reflection to get all of the values for the data and populate the controls on my form.
I am no longer able to cast the DetailData to my table because of the anonymous types.
I would like to be able to use reflection on the DetailData to get the values.
Thanks,
Brad
DetailData = (from db in priorityDataContext.tblDatabases
where db.DatabaseID == Id
select new
{
db.DatabaseID,
db.DatabaseName,
db.Purpose,
db.BackEnd,
db.FrontEnd,
db.Version,
db.ProducesReports,
db.MultiUser,
db.UserDescription,
Developer = priorityDataContext.func_get_employee_name(db.Developer),
DeptOwner = priorityDataContext.func_get_dept_name(db.DeptOwner),
db.Source_Code_Path,
db.Notes,
db.Active,
db.row_entry_time_stamp,
row_oper_name = priorityDataContext.func_get_employee_name(db.Developer),
db.row_last_chng_time_stamp,
row_last_chng_oper_name = priorityDataContext.func_get_employee_name(db.Developer)
}).SingleOrDefault();
protected virtual void PopulateDetailControlsA(List<Control> controlContainers, string srcDataTableName)
{
switch (srcDataTableName)
{
case "tblDatabase" :
break;
}
var database = (tblDatabase) DetailData;
var type = typeof(tblDatabase);
var properties = type.GetProperties(BindingFlags.Public | BindingFlags.Instance);
foreach (var controlContainer in controlContainers)
{
foreach (var propertyInfo in properties)
{
if (!ControlExists(controlContainer, propertyInfo.Name)) continue;
var txtExtControl = controlContainer.Controls[propertyInfo.Name] as ExtendedTextBox;
if (txtExtControl != null)
{
try
{
var value = propertyInfo.GetValue(database, null).ToString();
txtExtControl.Text = value;
}
catch (NullReferenceException)
{
}
continue;
}
var lnklblControl = controlContainer.Controls[propertyInfo.Name] as ExtendedLinkLabel;
if (lnklblControl != null)
{
try
{
var value = propertyInfo.GetValue(database, null).ToString();
lnklblControl.Text = value;
}
catch (NullReferenceException)
{
}
continue;
}
var chkControl = controlContainer.Controls[propertyInfo.Name] as ExtendedCheckBox;
if (chkControl != null)
{
try
{
var value = propertyInfo.GetValue(database, null).ToString();
switch (value)
{
case "True":
chkControl.CheckState = CheckState.Checked;
break;
case "False":
chkControl.CheckState = CheckState.Unchecked;
break;
}
}
catch (NullReferenceException)
{
chkControl.CheckState = CheckState.Indeterminate;
}
continue;
}
var cmbControl = controlContainer.Controls[propertyInfo.Name] as ExtendedComboBox;
if (cmbControl != null)
{
try
{
var value = propertyInfo.GetValue(database, null).ToString();
cmbControl.ValueMember = value;
}
catch (Exception ex)
{
}
continue;
}
}
}
}
What technology are you using for your UI? If you could use binding you would not need to worry about reflection on the anonymous type and then could also use converters if you need to format/calculate values from this.
From your response can't you just use the connection to the linq and then bind this to the combo box?
private void Form1_Load(object sender, System.EventArgs e)
{
var item = new DataClassesDataContext();
var stuff = item.Entity.Where(c => c.Property.Contains("something"));
comboBox1.DataSource = stuff;
comboBox1.DisplayMember = "Name";
comboBox1.ValueMember = "PIN";
}