I would like to bind a DataGridView to a different LINQ query every time (in order to reuse the same form/DGV for different queries), like this:
[Code]....
but the "Qry", and the number of comboboxes, and their field names would change every time.
I have users check off lab facilities in a UI. I want to use linq to fetch corresponding records for all of the labs that they have checked off. Basically,
Dim myRecs = (From l As EpiData In myDataContext.EPIDatas Where l.facility= _
one of the checked labs
So basically, I need to write a linq query where the "strings" to match are determined at runtime. Is there any way to do this easily? I know that there is a library out there called dynamic LINQ, but (1) it's in C# and I'm writing in VB (2) I'm really just looking for a single, simple solution for this single case.
I have been trying the following but it returns unexpected results:
Dim xd As XDocument = _
<?xml version="1.0" encoding="utf-8"?>
<root>
[code].....
The above result returns both 'element' nodes however it should only return the first where element/subelement@id=1/subsubelement@id=3 However if results.Ancestors. is used it returns the correct 'subelement' and if that line is not included it returns a single 'subsubelement' whih is also correct I don't understand why when mvoing to the 'element' it returns both (I realise both have a subelement with id=1 but I thought each further query would filter out the presvious results)?
I want to write a query that the "where" in the query is a string something like"
Dim query as string= "Name =xxxx and Date > 10 "
Dim t = from book in doc.Descendants("books") Select _
[Name] = book..value, [Date] = book..value....
Where (query)
I build the query string on run time
I have a listbox which users can select from a list if Towns, I want to be able to build a LINQ query based on the selected items in the list e.g.
[Code]...
I'm need to do the equivalent of a t-sql statement like this using LINQ:
SELECT * FROM mytable WHERE idnumber IN('1', '2', '3')
so in LINQ I have:
Dim _Values as String = "1, 2, 3"
Dim _Query = (From m In mytable Where idnumber = _Values Select m).ToList()
Not sure what to do with _Values to make idnumber evaluate each value in the string.
How do i great dynamic linq query in VB.net?
View 3 RepliesForgive my ignorance on this.I have this LINQ Query:Dim ngBikersDataContext As New CarBikeWalkDataContext
bikersList = (From c In ngBikersDataContext.Reg_Bikers _
Order By c.L_Name _
Select New Bikers() With { _
.BikerID = c.BikerID, _
.F_Name = c.F_Name, _
[Code]...
with the error "Overload resolution failed because no accesible 'Select' accepts this number of arguments."
Over the "NEW" I get an error " ')'expected."
I have an untyped dataset returned from my WebService. The user wants to dynamically construct a query referencing tables and columns and specifying values to test for.I have looked at Lambda Expressions and the Expressions.Expression Namespace. I think these provide the answer I'm looking for, but I'm not certain how to go about contructing the linq expressions to extract the datarows I'm looking for.
I plan on limiting the result to one datatable that the query will result in and i"ll provide the joins from the user's constructs.For a simple example I have a DataTable with (n) rows called "Table", and in it there is a computed column called "b_IsActive" that has the expression "Convert(IsActive, 'System.Boolean')". The user wants to retrieve all rows in "Table" where field "b_IsActive" is true.
I need to represent the following query using LINQ:
DECLARE @PurchasedInventoryItemID Int = 2
DECLARE @PurchasedInventorySectionID Int = 0
DECLARE @PurchasedInventoryItem_PurchasingCategoryID Int = 3
DECLARE @PurchasedInventorySection_PurchasingCategoryID Int = 0
[code]....
Now, I know that a query in .NET doesnt look like this, this is my test in the SQL Design Studio. Naturally VB.NET variables will be used in place of the SQL local variables.My problem is this: All of the conditions after "WHERE" are optional. In that a query might be made that uses one, some, all, or none of the conditions. V.PropertyID and V.Value can also appear any number of times.In VB.NET I can make this query easy enough by simply concatenating strings, and using a loop to append the "V.PropertyID/V.Value" conditions.I can also make a Stored Procedure in MS SQL, which is easy enough.However, I want to accomplish this using LINQ.
Is there a way to use Meta Tales or Table names to Construct a dynamic query in LINQ?
foreach (var metaTable in db.Mapping.GetTables())
{
var queryType = metaTable.RowType.Type;
[code]....
Is there a way to do something like this? The attempt above yields the error:Could not find an implementation of the query pattern for source type 'System.Data.Linq.ITable'. 'Select' not found. Consider explicitly specifying the type of the range variable 'q'.
I'm trying to query old Access database tables and compare them with SQL Server tables.They often don't have primary keys, or they have extra fields that had some purpose in the nineties, etc., or the new tables have new fields, etc.I need to find records - based on a set of fields specified at runtime - that are in one table but not another.So, I do this kind of query all the time in SQL, when I'm comparing data in different tables:
dim fields_i_care_about as string = "field1, field2, field3"
'This kind of thing gets set by a caller, can be any number of fields, depends on the
'table
dim s as string= ""
[code]....
It tells me it can't convert a Boolean - Is there any way to do this without Linq expressions? They seem far more complex than what I'm trying to do here, and they take a lot of code, and also I can't seem to find examples of Expressions where we're comparing two fields in a subquery.Is there a simpler way? I know I could do the usual EXISTS query using JOIN or IN - in this case I don't need the query to be super fast or anything. And I don't need to use a DataTable or DataSet - I can put the data in some other kind of object.
I have four comboboxes in my Ist form related to course as.c_type,c_stream,c_major,c_nature.......combobox c_type contains the type of courses like degree,diploma, PG etc,similarly "c_stream" contains stream like engg,medical etc. further c_major contains all courses like computer engg(CE),mechnical(ME), physiotherapy etc. and last c_nature has course nature whether regular or private or distance.Now situation is when i select diploma from c_type, corresponding options must be populate in c_stream like engg. And now when i select engg., CE or ME must be there in c_major combobox .Same is for C_nature.The all 4 combobox must show "please select" text on form load event..i also have 2nd form where i have same combobxs. so is there any way to call the same code without again writing that to 2nd form.
View 1 RepliesExample-I have a person class
Public Class Person
Private _fname As String
Public Property Fname() As String
[Code]...
i have created a dynamic tabpage and a dynamic tablelayoutpanel inside it then added dynamic textboxes and labels inside the tablelayoutpanel...the thing is , i am having a problem on how to access the value of those textboxes and labels and add them as new columns in the new table(tagpage) in mysql database, i can already create the table in the database but i cant add the new columns in it. heres the code for accessing the values of the labels and textboxes
error: NullReferenceException was unhandled....Object variable or With block variable not set.
sql = "alter table " & tbl_selected(counter) & " add " & frmMain.Controls("TLP_" & SecArrList_sp(counter2)).controls.item(SecArrList_sp(counter2) & "label" & counter).Text & " varchar(100) NULL;"
How would I get something like this to work so that I can dynamically alter the where-clause in this linq to sql query?
Dim AccountID = 1234
Dim AccountList
Select Case Types
[Code]....
With the above code I get this error:
Late binding operations cannot be converted to an expression tree
Basically i have one TabControl with a form and 2 browsers within one form I have ProBlem To call the dynamic browser to navigate with dynamic Textbox.text
[Code]...
UPDATE: Groo's answer was marked correct as it would be a good alternative. I decided to stick with the select/switch statements to avoid the performance issues of using reflection. As far as I can tell there is no way to do what I want without using Dynamic LINQ (and reflection) or a decompiler (to manually code each LINQ statement, which I am already doing by hand). Note: to make this update DropDownList16 through DropDownList20 were removed (needed the characters).Is there a way to abstract the building of a dynamic Linq to SQL query?
I am trying to build a Linq to SQL query with a dynamic where clause, based on user supplied filters. The user needs to be able to filter strings, integers, and dates using advanced options (equal, not equal, contains, starts with, etc). The user needs to be able to use these filters with as many or few columns as desired.
[Code]...
Dim query=Form f in BBSDb.Forms order by f.FormID Descending Select f where I want the f.FormID to be able to replace with a variable..What I mean is.. it doesn't have to f.FormID .. I may want to set f.FormName to be in descending for example using the code dynamically.. Is there anyway to achive?
View 2 RepliesThis is an extension of my last question which was answered, so I am starting a new thread. I have a query in LINQ that I was given to trim down the columns of a datatable. This works well, however, I need to make the LINQ query dynamic. So the query below:
Dim qColumnsIWant = From row As DataRow In inDT.AsEnumerable() _
Select _
EPN = row.Field(Of Integer)("EPNID"), _
EPNID = row.Field(Of String)("EPNNumber"), _
Ingot = row.Field(Of String)("Ingot"), _
ShopOrder = row.Field(Of String)("ShopOrder")
For comparison: something like the shirt builder application at [URL]Say, if I have fabric image and want to generate base, collar, cuff etc. How should I do it on server side in .NET, and generate different components of shirt.
View 1 RepliesI have a SQL database which I'm running a query against to return a list of names - eg using "select names from table"I would like to add all of these names to an array so I can use them later. To do this I would need to use a dynamic array as the number of names returned could be anything.Apart from first running "select count(names) from table", getting a value and then Redim'ing the array on the count is there another method I can use.I've seen there's a dataset row.count? Can I somehow use this?
connection.Open()
reader = command.ExecuteReader()
While reader.Read()
[code]....
I'm making a new design for my website, but I want to keep the old one and possibly switch between the two.
Unfortunately, I've changed the content on the Master Page (luckily I have a backup).What I was thinking was to keep separate master files for each theme, and then just determine which one to server based on which stylesheet is loaded.
The only way I can think to do this is to keep a "settings" file on the website that has a "stylesheet=1/2/3/4/etc" line. Depending on the number there, the server will serve the correct master page.
Alternatively it might be easier to do something similar, but instead of serving a whole different master page, set a specific stylesheet to use.In both cases, I need a little help with actually doing the work on the server. I can read a text file (even encrypt/decrypt a file before and after it gets read for security), but actually giving the server the instructions based on what is read is where I'm lost.
I have an array filled with values from Excel cells. Each of the values is a concatenation of two things separated by a pipe, like "Machines|MachinesCode"
I need to, as I fill this array, strip out the pipe and everything in front of it so that the array being filled is only filled with the "MachinesCode" part of the cell value, but I haven't had much luck finding how I should do this. Each cell is dynamically filled and will never have a set length, so I can't set a trip by a particular number value of characters in the strings.
This subroutine is what I'm using. I am filling array FieldArray with another array (ExcelArray) currently holding the concatenated values.
Public Shared Sub PopulateFieldArray(ByRef FieldArray() As String, ByVal iFieldCount As Integer, ByVal ExcelArray(,) As Object)
Dim iIndex As Integer
For iIndex = 1 To iFieldCount
FieldArray(iIndex) = CStr(ExcelArray(2, iIndex))
Next
End Sub
But I don't know what to wrap around the CStr Excel array to cut off the pipe and all values before it while I fill FieldArray.
When i press W, i'm creating a dynamic picturebox of a bullet but i have no clue how to make it move to the target.I can create myself a picturebox and call it picBullet1, but what about bullet 2, 3,4 etc? what should i read/learn?
View 3 RepliesWe have a GUI that displays a radio selection box (3 options) that are the three sites where our hospitals are. We need to dropdown located on the form to fill with only the locations based on the selected radio option.
Here is the code behind we have so far (sorry, VB)
[Code]....
For the record the Location dropdown is currently databound but its a static SELECT statement which brings us all the locations but we'd prefer it to be cleaner if it only returned the locations based on Site. We are using Visual Basic 2008 Express Edition for development.
ArrayList is a generic structure. Let's say I have my own structure (contained of Boolean+string+int). I want to set a dynamic array based on my own structure. How....?
View 9 RepliesIve managed to dynamically create a form, and dynamically create a timer, but i have not been able to create the timer on the dynamic form. Specifically, i need to be able to have the timer itself create another form with a timer. (I realize that this would create a new form every interval on the timer, that is what i want to do)
1. A way to add the timer to the dynamic form, and maintain the timer sub on my main form.
2. A way to create the whole thing over (dynamic form and timer) through the previous dynamic form and timer.
I was thinking i could use a collection/array to store the forms and timers, but i'm still having trouble figuring out how to add entire forms or timers into a list. (A timer is not considered a control, so i cant use a controlcollection...)
Heres my code;
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
Dim frm As New Form
[Code]....
*EDIT* Btw, my idea was to use i as a variable that increases every time a form is created, then insert the form into the array, with i as the integer. i just need to know how to create a new form with a different name each time. (as with timers)
I have been looking into dynamic querying of datasets and the use of copytodatatable() for a project. I have seen in alot of forums that the copytodatatable functionality is unusable as it was removed. have an example of a dynamic Linq query being loaded into a datatable.
View 1 RepliesI have the following linq query:
Dim q = From definition In definitionList _
Where definition.ValueDefName.Contains(criteria)[code]....
I have already looked into this answer: LINQ - dynamic WHERE clause?Unfortunately, it doesn't work for me using .net 4.0. When I attempt to pass the criteria string in it ask for a predicate. The end goal is to add any of these:
definition.ValueDefname.Contains(criteria)
definition.ValueDefDesc.Contains(criteria)
definition.Aliaslist.Contains(Criteria)
definition.StrategicInitiative.Contains(Criteria)
to be passed into the query depending on what checkboxes the user has selected. How can I create a dynamic where clause in linq to sql? Is there new syntax for passing in a where clause as a string?