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  • LINQ: why does this query not work on an ArrayList?

    - by Benny
    public static ArrayList GetStudentAsArrayList() { ArrayList students = new ArrayList { new Student() { RollNumber = 1,Name ="Alex " , Section = 1 ,HostelNumber=1 }, new Student() { RollNumber = 2,Name ="Jonty " , Section = 2 ,HostelNumber=2 } }; return students; } The following code doesn't compile. The error is ArrayList is not IEnumerable ArrayList lstStudents = GetStudentAsArrayList(); var res = from r in lstStudents select r; This compiles: ArrayList lstStudents = GetStudentAsArrayList(); var res = from Student r in lstStudents select r; Can anybody explain what the difference is between these two snippets? Why the second works?

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  • Is saving to database just to get an ID a bad hack?

    - by Narsil
    I hope the title is not too confusing. I am trying to make folders with linq-to-sql objects' IDs. Actually I have to create folders before I should save them. I will use them to keep user uploaded files. As you can see I have to create the folder with the FileID before I can save it there. So I just save a record which will be edited or maybe deleted File newFile = new File(); ...//add some values to fields so they don't throw rule violations db.AddFile(newFile); db.Save(); System.IO.Directory.CreateDirectory("..Uploads/"+newFile.FileId.ToString()); After that I will have to edit some fields and save again. Of course user might stop upload and I would have to delete it. I know I can write a stored procedure to get the next available FileID but some other upload happening at the same time would get the same number. So they would write in same directory which is a thing I don't want. Should I go on with this, would there be some problems? Can you think of a better way?

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  • SQL placeholder in WHERE IN issue, inserted strings fail.

    - by Alastair Pitts
    As part of my jobs, I need to writes SQL queries to connect to our PI database. To generate a query, I need to pass an array of tags (essentially primary keys), but these have to be inserted as strings. As this will be a modular query and used for multiple tags, a placeholder is being used. The query relies upon the use of the WHERE IN statement, which is where the placeholder is, like below: SELECT SUM(value * 5/1000) as "Hourly Flow [kL]" from piarchive..pitotal WHERE tag IN (?) AND time between ? and ? and timestep = '1d' and calcbasis = 'Eventweighted' and value <> '' The issue is the format in which the tags are to be passed in as. If I add them directly into the query (for testing), they go in the format (these are example numbers): '000000012','00000032','005050236','4560236' and the query looks like: SELECT SUM(value * 5/1000) as "Hourly Flow [kL]" from piarchive..pitotal WHERE tag IN ('000000012','00000032','005050236','4560236') AND time between ? and ? and timestep = '1d' and calcbasis = 'Eventweighted' and value <> '' which works. If I try and add the same tags into the placeholder, the query fails. If I only add 1 tag, with no quotes (using the placeholder), the query works. Why is this happening? Is there anyway around it?

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  • Django generic relation field reports that all() is getting unexpected keyword argument when no args

    - by Joshua
    I have a model which can be attached to to other models. class Attachable(models.Model): content_type = models.ForeignKey(ContentType) object_pk = models.TextField() content_object = generic.GenericForeignKey(ct_field="content_type", fk_field="object_pk") class Meta: abstract = True class Flag(Attachable): user = models.ForeignKey(User) flag = models.SlugField() timestamp = models.DateTimeField() I'm creating a generic relationship to this model in another model. flags = generic.GenericRelation(Flag) I try to get objects from this generic relation like so: self.flags.all() This results in the following exception: >>> obj.flags.all() Traceback (most recent call last): File "<console>", line 1, in <module> File "/usr/local/lib/python2.6/dist-packages/django/db/models/manager.py", line 105, in all return self.get_query_set() File "/usr/local/lib/python2.6/dist-packages/django/contrib/contenttypes/generic.py", line 252, in get_query_set return superclass.get_query_set(self).filter(**query) File "/usr/local/lib/python2.6/dist-packages/django/db/models/query.py", line 498, in filter return self._filter_or_exclude(False, *args, **kwargs) File "/usr/local/lib/python2.6/dist-packages/django/db/models/query.py", line 516, in _filter_or_exclude clone.query.add_q(Q(*args, **kwargs)) File "/usr/local/lib/python2.6/dist-packages/django/db/models/sql/query.py", line 1675, in add_q can_reuse=used_aliases) File "/usr/local/lib/python2.6/dist-packages/django/db/models/sql/query.py", line 1569, in add_filter negate=negate, process_extras=process_extras) File "/usr/local/lib/python2.6/dist-packages/django/db/models/sql/query.py", line 1737, in setup_joins "Choices are: %s" % (name, ", ".join(names))) FieldError: Cannot resolve keyword 'object_id' into field. Choices are: content_type, flag, id, nestablecomment, object_pk, timestamp, user >>> obj.flags.all(object_pk=obj.pk) Traceback (most recent call last): File "<console>", line 1, in <module> TypeError: all() got an unexpected keyword argument 'object_pk' What have I done wrong?

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  • How can I use Hibernate Criteria's to query nested tables?

    - by cbmeeks
    I've looked all over SO and Google but I guess I'm not using the right search terms or something. Anyway, say I have three tables: Companies ----------------------------------------- id name user_id Users ----------------------------------------- id username usertype_id UserTypes ----------------------------------------- id typeofuser So ACME would be a company, it would have a user Moe and Moe would be a usertype of Stooge. In SQL, I would do something like: select * from companies c join users u on (u.id = c.user_id) join usertypes ut on (ut.id = u.usertype_id) where ut.typeofuser = 'Stooge' But I can't seem to figure out how to do that in a Criteria. I have tried: Criteria crit = io.getSession().createCriteria(Company.class); List<Company> list = crit.createCriteria("users") .createCriteria("usertypes") .add(Restriction.eq("typeofuser", "Stooge").list(); But I get back way too many records. And the results don't even come close to being accurate. I've also tried: Criteria crit = io.getSession().createCriteria(Company.class); List<Company> list = crit.createAlias("users", "u") .createAlias("u.usertypes", "ut") .add(Restriction.eq("ut.typeofuser", "Stooge").list(); Seems to bring back the exact same result set. I actually have read the user manual. And when I nest only one level deep (ie, searching by users is fine) but when I get two layers deep, I can't quite get it. And the manual is no help. I just can't relate cats and kittens to business objects. Maybe they should use cats, kittens and fleas? :-/ Thanks for any suggestions.

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  • Is it actually possible to connect to ActiveMQ via XMPP and query/browse queues using "AciveMQ.Agen

    - by Oleg Kiorsak
    I tried what I think are 4 most popular XMPP (aka "Jabber") clients (Spark, Pidgin, Psi, Pandion) to connect to ActiveMQ instance (Apache ActiveMQ ver. 5.3.0) on XMMP connector with an idea to use the "AciveMQ.Agent chatroom" for querying queues/etc and no success at all Some of them fail with 'Unknown error', some don't fail but kind of "hang"... interestingly, some communication does indeed reach the ActiveMQ side, because when I close a client it spits an exception "could not close" or something to that effect... and if I try "register new user" option (present on most clients" the ActiveMQ also spits some most cryptic warning message But I was never able to get to the point when I could see or specify "ActiveMQ.Agent" as chatroom and issue any commands... Before I waste any more time on this curious feature, I would like to hear whether anyone had any success with it? Thank you! PS: BTW, the book "ActiveMQ in Action book" http://www.manning.com/snyder/ shows that it is apparently works and is very easy using some Mac client (AdiumX), but I wanted it on a Windows PC ;)

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  • SQL query for getting data in two fields from one column.

    - by AmiT
    I have a table [Tbl1] containing two fields. ID as int And TextValue as nvarchar(max) Suppose there are 7 records. I need a resultset that has two columns Text1 and Text2. The Text1 should have first 4 records and Text2 should have remaining 3 records. [Tbl1] ID | TextValue 1. | Apple 2. | Mango 3. | Orange 4. | Pineapple 5. | Banana 6. | Grapes 7. | Sapota Now, the result-set should have Text1 | Text2 Apple | Banana Mango | Grapes Orange | Sapota Pineapple |

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  • Is this the right way to organize my database tables?

    - by Moss
    So I'm making a website that allows users to build contact lists. So their are users, the users have lists, and the lists have contacts. It seems to me that I need 3 tables for this but I just want to make sure. There would be a User table of course, and then a "List of Lists" table that has the username, and listname, as primary key along with whatever other info we want to attach to the lists as a whole. Finally, for lack of a better word, the List table which would again have the username/listname p.k., then the contact ID and notes and such that the user attaches to that contact on that specific list. I hope that is a clear explanation. For some reason I feel unsure about this arrangement. For one thing if the website becomes popular the List table could swell to billions of rows. And it also feels a little weird that everybody's list info is all jumbled up in the same table. I suppose I could create separate tables for each user and even for each list but that seems like a bad idea for other reasons. My db explanation assumes I can use foreign keys on my tables which at the moment isn't actually an option. If I can't get InnoDB tables enabled I will probably use ID's for the lists instead of depending on a compound key. Maybe I should do this anyway?

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  • Designing DAL in .NET to be "data-source independent" and not just "database independent" ?

    - by Munish Goyal
    How to design such flexible DAL (specifically in .NET) ? What interfaces .NET provides and what should be done on my own ? Its a greenfield project starting with SQL Server as data source but in future, parts of it will move to different NoSQL type of datastores. Also, we may need to experiment with lot of different datastores (like some data may have to go with Cassandra, some with RDBMS, some to other DHT etc.) Therefore easily switchable access layer will be needed. All i know right now is the 'data' and 'operations needed on that data'.

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  • SQL Server 2008 need just like crosstab query on XML column?

    - by user1332896
    <abc id="abc1"> <def id="def1"> <ghi att='ghi1'> <mn id="0742d2ea" name="RF" dt="0" df="3" ty="0" /> <mn id="64d9a11b" name="CJ" dt="0" df="3" ty="0" /> <mn id="db72d154" name="FJ" dt="2" df="4" ty="0" /> <mn id="39af9fa1" name="BS" dt="0" df="2" ty="0" /> </ghi> <jkl att='jkl1'> <mn id="0742d2ea" name="RF" dt="1" gl="19" /> <mn id="64d9a11b" name="CJ" dt="0" gl="6" /> <mn id="db72d154" name="FJ" dt="0" gl="0" /> <mn id="39af9fa1" name="BS" dt="0" gl="12" /> <mn id="ac4f566f" name="DJ" dt="0" gl="9" /> <mn id="4bf3ba2f" name="RP" dt="0" gl="16" /> <mn id="db1af021" name="SC" dt="1" gl="10" /> <mn id="c4c93a2d" name="DN" dt="1" gl="15" /> </jkl> </def> </abc> I need this output. Is this possible in SQL Server 2008? id name ghiDT ghiDF ghiTY jklDT jklGL 0742d2ea RF 0 3 0 1 19 64d9a11b CJ 0 3 0 0 6 db72d154 FJ 2 4 0 0 0 39af9fa1 BS 0 2 0 0 12 ac4f566f DJ 0 0 0 0 9 4bf3ba2f RP 0 0 0 0 16 db1af021 SC 0 0 0 1 10 c4c93a2d DN 0 0 0 1 15

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  • POST variables to web server?

    - by OverTheRainbow
    Hello I've been trying several things from Google to POST data to a web server, but none of them work: I'm still stuck at how to convert the variables into the request, considering that the second variable is an SQL query so it has spaces. Does someone know the correct way to use a WebClient to POST data? I'd rather use WebClient because it requires less code than HttpWebRequest/HttpWebResponse. Here's what I tried so far: Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click Dim wc = New WebClient() 'convert data wc.Headers.Add("Content-Type", "application/x-www-form-urlencoded") Dim postData = String.Format("db={0}&query={1}", _ HttpUtility.UrlEncode("books.sqlite"), _ HttpUtility.UrlEncode("SELECT id,title FROM boooks")) 'Dim bytArguments As Byte() = Encoding.ASCII.GetBytes("db=books.sqlite|query=SELECT * FROM books") 'POST query Dim bytRetData As Byte() = wc.UploadData("http://localhost:9999/get", "POST", postData) RichTextBox1.Text = Encoding.ASCII.GetString(bytRetData) Exit Sub Dim client = New WebClient() Dim nv As New Collection nv.Add("db", "books.sqlite") nv.Add("query", "SELECT id,title FROM books") Dim address As New Uri("http://localhost:9999/get") 'Dim bytRetData As Byte() = client.UploadValues(address, "POST", nv) RichTextBox1.Text = Encoding.ASCII.GetString(bytRetData) Exit Sub 'Dim wc As New WebClient() 'convert data wc.Headers.Add("Content-Type", "application/x-www-form-urlencoded") Dim bytArguments As Byte() = Encoding.ASCII.GetBytes("db=books.sqlite|query=SELECT * FROM books") 'POST query 'Dim bytRetData As Byte() = wc.UploadData("http://localhost:9999/get", "POST", bytArguments) RichTextBox1.Text = Encoding.ASCII.GetString(bytRetData) Exit Sub End Sub Thank you.

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  • Query XML file with PHP to return certain bookmarks...

    - by josh brown
    I have an XML file full of bookmarks from Google Bookmarks. (File: http://gist.github.com/324844) I want to pull the bookmark based on this path: xml_api_reply-bookmarks-bookmark-labels-label. So, my question is How can I use SimpleXML to grab the bookmarks that have the label Inspiration? Some bookmarks may have more than one bookmark.

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  • can you make an sql query for this situation?

    - by saurav
    i have a table as below. name and 10 cities in which he lived during his lifetime. name , city1 , city2 , city3 ,city4 , city5 ,city6 , city7 , city8 , city9 city10 suppose for a particular name i want to fetch other names in table matching with maximum number of cities. for example if i want to fetch other people who have lived in three or more cities lived by this person.

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  • Best way to convert a Unicode URL to ASCII (UTF-8 percent-escaped) in Python?

    - by benhoyt
    I'm wondering what's the best way -- or if there's a simple way with the standard library -- to convert a URL with Unicode chars in the domain name and path to the equivalent ASCII URL, encoded with domain as IDNA and the path %-encoded, as per RFC 3986. I get from the user a URL in UTF-8. So if they've typed in http://?.ws/? I get 'http://\xe2\x9e\xa1.ws/\xe2\x99\xa5' in Python. And what I want out is the ASCII version: 'http://xn--hgi.ws/%E2%99%A5'. What I do at the moment is split the URL up into parts via a regex, and then manually IDNA-encode the domain, and separately encode the path and query string with different urllib.quote() calls. # url is UTF-8 here, eg: url = u'http://?.ws/?'.encode('utf-8') match = re.match(r'([a-z]{3,5})://(.+\.[a-z0-9]{1,6})' r'(:\d{1,5})?(/.*?)(\?.*)?$', url, flags=re.I) if not match: raise BadURLException(url) protocol, domain, port, path, query = match.groups() try: domain = unicode(domain, 'utf-8') except UnicodeDecodeError: return '' # bad UTF-8 chars in domain domain = domain.encode('idna') if port is None: port = '' path = urllib.quote(path) if query is None: query = '' else: query = urllib.quote(query, safe='=&?/') url = protocol + '://' + domain + port + path + query # url is ASCII here, eg: url = 'http://xn--hgi.ws/%E3%89%8C' Is this correct? Any better suggestions? Is there a simple standard-library function to do this?

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  • named_scope + average is causing the table to be specified more then once in the sql query run on po

    - by hadees
    I have a named scopes like so... named_scope :gender, lambda { |gender| { :joins => {:survey_session => :profile }, :conditions => { :survey_sessions => { :profiles => { :gender => gender } } } } } and when I call it everything works fine. I also have this average method I call... Answer.average(:rating, :include => {:survey_session => :profile}, :group => "profiles.career") which also works fine if I call it like that. However if I were to call it like so... Answer.gender('m').average(:rating, :include => {:survey_session => :profile}, :group => "profiles.career") I get... ActiveRecord::StatementInvalid: PGError: ERROR: table name "profiles" specified more than once : SELECT avg("answers".rating) AS avg_rating, profiles.career AS profiles_career FROM "answers" LEFT OUTER JOIN "survey_sessions" survey_sessions_answers ON "survey_sessions_answers".id = "answers".survey_session_id LEFT OUTER JOIN "profiles" ON "profiles".id = "survey_sessions_answers".profile_id INNER JOIN "survey_sessions" ON "survey_sessions".id = "answers".survey_session_id INNER JOIN "profiles" ON "profiles".id = "survey_sessions".profile_id WHERE ("profiles"."gender" = E'm') GROUP BY profiles.career Which is a little hard to read but says I'm including the table profiles twice. If I were to just remove the include from average it works but it isn't really practical because average is actually being called inside a method which gets passed the scoped. So there is some times gender or average might get called with out each other and if either was missing the profile include it wouldn't work. So either I need to know how to fix this apparent bug in Rails or figure out a way to know what scopes were applied to a ActiveRecord::NamedScope::Scope object so that I could check to see if they have been applied and if not add the include for average.

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  • Editing/Updating one of the results in a search query.

    - by eggman20
    Hi guys. I'm creating a page that searches for an item and then be able to edit/update it. I was able to do it when it returns just one result but when it gives me multiple results I could only edit the very last item. Below is my code: ....... $dj =$_POST[djnum]; $sql= "SELECT * From dj WHERE datajack LIKE '$dj%'"; $result = mysql_query($sql); //more code in here// while ($info =mysql_fetch_array($result)) { // display the result echo "<form action=\"dj_update.php\" method=\"POST\"><input type=\"hidden\" name=\"djnumber\" value=\"".$info['datajack']."\">"; echo "<tr><td>DJ ".$info['datajack']."</td>"; echo "<td>".$info['building']."&nbsp;</td>"; echo "<td>Rm ".$info['room']."&nbsp;</td>"; echo "<td>".$info['switch']."&nbsp;</td>"; echo "<td>".$info['port']."&nbsp;</td>"; echo "<td>".$info['notes']."&nbsp;</td>"; echo "<td style=\"text-align:center;\"><input type=\"Submit\" value=\"Edit\" ></td></tr>"; } // more code here // Then this is the screen shot of the result: The idea is the user should be able to click on "Edit" and be able to edit/update that particular item. But when I click any of the Edit button I could only edit the last item. What am I missing here? Is there an easier way to do this? Thanks guys and Happy new year!

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  • How to pass special characters so ASP.NET MVC can handle correctly query string data?

    - by labilbe
    Hello, I am using a route like this one: routes.MapRoute("Invoice-New-NewCustomer", "Invoice/New/Customer/New/{*name}", new { controller = "Customer", action = "NewInvoice" }, new { name = @"[^\.]*" }); There is an action which handles this route: public ActionResult NewInvoice(string name) { AddClientSideValidation(); CustomerViewData viewData = GetNewViewData(); viewData.InvoiceId = "0"; viewData.Customer.Name = name; return View("New", viewData); } When I call return RedirectToAction("NewInvoice", "Customer", new {name}); and name is equal to "The C# Guy", the "name" parameter is truncated to "The C". So my question is : What is the best way to handle this kind of special character with ASP.NET MVC? Thanks!

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  • How to iterate all query paths within an image header namespace in WIC?

    - by muruge
    Hello All, I am using Windows Imaging Component to read/write image metadata in my WPF application. I would like to know if there is an efficient way to know if any paths exist within a namespace. For instance I would like to know if any paths within IPTC namespace exist and if not I want to delete the namespace from the image header. Any pointers would be greatly appreciated. Thanks, Murugesh.

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  • Is Django's manage.py syncdb or South used to create the test database?

    - by Thierry Lam
    With Django 1.1.1 and South 0.62, running a test from the CLI usually have the following output: Creating table some_model Installing index for my_app.SomeModel model . ----- Ran 1 test in 1s OK After upgrading to South 0.7, the output is invoking South's migration: Creating table some_model Installing index for my_app.SomeModel model Migrating... Running migrations for my_app: - Migrating forwards to 0001_initial > my_app:0001_initial - Loading initial data for my_app Migrated: - my_app . ----- Ran 1 test in 1s OK To create the test DB, has the test always used South migration in the past(before South 0.7) even if the output is not explicitly being shown?

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  • How to avoid timestamp issue in a long query?

    - by pingi
    Hi, I have the following 2 tables: items: id int primary key bla text events: id_items int num int when timestamp without time zone ble text composite primary key: id_items, num and want to select to each item the most recent event (the newest 'when'). I wrote an request, but I don't know if it could be written more efficiently. Also on PostgreSQL there is a issue with comparing Timestamp objects: 2010-05-08T10:00:00.123 == 2010-05-08T10:00:00.321 so I select with 'MAX(num)' Any thoughts how to make it better? Thanks. SELECT i.*, ea.* FROM items AS i JOIN ( SELECT t.s AS t_s, t.c AS t_c, max(e.num) AS o FROM events AS e JOIN ( SELECT DISTINCT id_item AS s, MAX(when) AS c FROM events GROUP BY s ORDER BY c ) AS t ON t.s = e.id_item AND e.when = t.c GROUP BY t.s, t.c ) AS tt ON tt.t_s = i.id JOIN events AS ea ON ea.id_item = tt.t_s AND ea.cas = tt.t_c AND ea.num = tt.o;

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  • Favouriting things in a database - most efficient method of keeping track?

    - by a2h
    I'm working on a forum-like webapp where I'd like to allow users to favourite an item so that they can keep track of it, and also so that others can see how many times an item's been favourited. The problem is, I'm unsure on the best practices for databases, which includes this situation. I have two ideas in my head on how to do this: Add an extra column to the user table and store things like so: "|2|5|73|" Add an extra table with at least two columns, one for referencing an item, the other for referencing a user. I feel uncomfortable about going for the second method as it involves an extra table, and potentially more queries would be required. Perhaps these beliefs aren't an issue, as I have little understanding of databases beyond simply working with table layouts and basic queries.

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