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  • using a connection string in web.config for crystal report

    - by zombiegx
    I`m having problems between two servers, wich use differente odbc dsn. My apps work great but crystal reports uses the original odbc connection, how can I fix this? I'm thinking of using the same connection string in the web.config, but I don't know how. found this but is too confusing for me this is an example of my code, its a aspx file that loads as a pdf protected void Page_Load(object sender, EventArgs e) { try { var par = Request.QueryString; int pidmun = 0; if (!string.IsNullOrEmpty(Request["id"])) { pidmun = int.Parse(Request["id"]); } string pFechaIni = Request["fi"]; string pFechaFin = Request["ff"]; string pTipo = Request["t"]; string pNombreMunicipio = Request["nm"]; var pos = Request.Form; if (string.IsNullOrEmpty(pFechaIni)) { pFechaIni = "01/01/2010"; } if (string.IsNullOrEmpty(pFechaFin)) { pFechaFin = "01/01/2010"; } if (string.IsNullOrEmpty(pTipo)) { pTipo = "FOLIO"; } if (string.IsNullOrEmpty(pNombreMunicipio)) { pNombreMunicipio = "NombreMunicipio"; } ReporteIngresos report = new ReporteIngresos(); TextObject nom; TextObject periodo; nom = (TextObject)report.ReportDefinition.ReportObjects["TxtNombreMunicipio"]; periodo = (TextObject)report.ReportDefinition.ReportObjects["TxtPeriodo"]; nom.Text = "Ingresos Municipio de " + pNombreMunicipio; periodo.Text = "Periodo del " + pFechaIni + " al " + pFechaFin; report.SetParameterValue("pidMun", pidmun); report.SetParameterValue("pFechaIni", pFechaIni); report.SetParameterValue("pFechaFin", pFechaFin); report.SetParameterValue("pTipo", pTipo); MemoryStream oStream; oStream = (MemoryStream)report.ExportToStream(CrystalDecisions.Shared.ExportFormatType.PortableDocFormat); Response.Clear(); Response.Buffer = true; Response.AddHeader("CustomHeader", "ReporteIngresos"); Response.CacheControl = "No-cache"; Response.ContentType = "application/pdf"; Response.BinaryWrite(oStream.ToArray()); Response.End(); } catch (Exception ex) { ExBi.log(ex); throw ex; } } thanks.

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  • replace values in a String from a Hashtable in Java

    - by Adnan
    My string looks like; String values = "I am from UK, and you are from FR"; and my hashtable; Hashtable countries = new Hashtable(); countries.put("United Kingdom", new String("UK")); countries.put("France", new String("FR")); What would be the most effective way to change the values in my string with the values from the hashtable accordingly. These are just 2 values to change, but in my case I will have 100+

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  • Hibernate querycount query, dont know how to do

    - by kevinb92
    I want to make an hibernate querycount on a table. I have to values, one string and one boolean HibernateUtil.queryCount(VoteOnPublication.class, new String[] {VOTED_PUBLICATION_ID_FIELD, FOR_OR_AGAINST_FIELD}, **********); my voted_publication_id_field is a string, and my for or against field is a boolean. What should i put in my second part of the query ? I first put : new String[] {publication.getId(),true.toString() but that didnt work. i think the new String is the mistake but i dont know what to put

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  • What is the Microsoft Query Syntax for Subqueries?

    - by Kuyenda
    I am trying to do a simple subquery join in Microsoft Query, but I cannot figure out the syntax. I also cannot find any documentation for the syntax. How would I write the following query in Microsoft Query? SELECT * FROM ( SELECT Col1, Col2 FROM `C:\Book1.xlsx`.`Sheet1$` ) AS a JOIN ( SELECT Col1, Col3 FROM `C:\Book1.xlsx`.`Sheet1$` ) AS b ON a.Col1 = b.Col1 Is there official documentation for Microsoft Query? Thanks!

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  • MySQL query using multiple criteria from checkboxes

    - by jungle_programmer
    I would like to do a multiple search query usig multiple checkboxes which represent particular textboxes. How do i create a mysql query which will be filtering the checked and unchecked checkboxes (probably using if statements)? The query should be able to filter the checked and ucnchecked boxes and query them using the AND condition. Thanks

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  • how can I count number of occurance of a word in a string while ignoring cases

    - by Ronny
    I am trying to count the number of occurance of a given word while ignoring cases. I have tried <?php $string = 'Hello World! EARTh in earth and EARth';//string to look into. if(stristr($string, 'eartH')) { echo 'Found';// this just show eartH was found. } $timesfound = substr_count($string, stristr($string, 'eartH'));// this count how many times. echo $timesfound; // this outputs 1 instead of 3.

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  • Using Yahoo local search query for iPhone

    - by robbmcmahan
    I'm using yahoo local search in an iPhone app and trying to query everything in a certain location. According to the api docs you can pass "*" to query and it will return everything. I've tried passing it several different ways, including the way below but it does not work unless I actually pass it a real query. Does anyone know how or what I need to pass to make it query everything? [self setQuery:[@"*" stringByAddingPercentEscapesUsingEncoding:NSASCIIStringEncoding]]; Thanks

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  • Query between SQL server and Client side

    - by Karim
    I create a query: Select * from HR_Tsalary where month='3' and year ='2010' the result is 473 records and I found 2 duplicate record, then I create another query to find duplicate record only: SELECT Emp_No, COUNT(*) FROM HR_Tsalary WHERE year = '10' AND month = '3'GROUP BY Emp_No HAVING COUNT(*) 1 the result is zero record from client side (thru Visual Basic Adodb code). But when I use same query from server the result is 2 records. Is there any different when create a query between from server side and client side?

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  • directory services group query changing randomly

    - by yamspog
    I am receiving an unusual behaviour in my asp.net application. I have code that uses Directory Services to find the AD groups for a given, authenticated user. The code goes something like ... string username = "user"; string domain = "LDAP://DC=domain,DC=com"; DirectorySearcher search = new DirectorySearcher(domain); search.Filter = "(SAMAccountName=" + username + ")"; And then I query and get the list of groups for the given user. The problem is that the code was receiving the list of groups as a list of strings. With our latest release of the software, we are starting to receive the list of groups as a byte[]. The system will return string, suddenly return byte[] and then with a reboot it returns string again. Anyone have any ideas? code sample: DirectoryEntry dirEntry = new DirectoryEntry("LDAP://" + ldapSearchBase); DirectorySearcher userSearcher = new DirectorySearcher(dirEntry) { SearchScope = SearchScope.Subtree, CacheResults = false, Filter = ("(" + txtLdapSearchNameFilter.Text + "=" + userName + ")") }; userResult = userSearcher.FindOne(); ResultPropertyValueCollection valCol = userResult.Properties["memberOf"]; foreach (object val in valCol) { if (val is string) { distName = val.ToString(); } else { distName = enc.GetString((Byte[])val); } }

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  • Dovecot unable to perform mysql query

    - by NathanJ2012
    I have been following the ISPMail tutorials on workaround.org (the 2.9 Wheezy version) and thus far everything has been working fine. When I reached the step to "Testing email delivery" step I noticed a error about the query in the output log from /var/log/mail.log. May 14 06:48:59 mail postfix/pickup[17704]: EA4AD240A98: uid=0 from=<root> May 14 06:48:59 mail postfix/cleanup[17776]: EA4AD240A98: message-id=<[email protected]> May 14 06:48:59 mail postfix/qmgr[17706]: EA4AD240A98: from=<[email protected]>, size=429, nrcpt=1 (queue active) May 14 06:49:00 mail dovecot: auth-worker(17782): mysql(127.0.0.1): Connected to database mailserver May 14 06:49:00 mail dovecot: auth-worker(17782): Warning: mysql: Query failed, retrying: Table 'mailserver.users' doesn't exist May 14 06:49:00 mail dovecot: auth-worker(17782): Error: sql([email protected]): User query failed: Table 'mailserver.users' doesn't exist (using built-in default user_query: SELECT home, uid, gid FROM users WHERE username = '%n' AND domain = '%d') May 14 06:49:00 mail dovecot: lda([email protected]): msgid=<[email protected]>: saved mail to INBOX May 14 06:49:00 mail postfix/pipe[17780]: EA4AD240A98: to=<[email protected]>, relay=dovecot, delay=0.09, delays=0.03/0.01/0/0.06, dsn=2.0.0, status=sent (delivered via dovecot service) May 14 06:49:00 mail postfix/qmgr[17706]: EA4AD240A98: removed I found this rather interesting that it isn't finding the DB so I went back through and checked EVERY file that I touched that involved the DB (including the postfix cf files) and everything is correct so I am baffled at this point, but oddly enough it would seem the email still made it to the correct destination in /var/vmail/domain.com/. Should I be worried about this or am I missing something here? Since it is a message from dovecot it would be the query from dovecot-sql.conf.ext which I am including here driver = mysql connect = host=127.0.0.1 dbname=mailserver user=blocked password=***REMOVED*** default_pass_scheme = PLAIN-MD5 password_query = SELECT email as user, password FROM virtual_users WHERE email='%u';

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  • Android openvpn + zeroconf browser sending mdns query packets over eth0 instead of tap0 interface on wifi

    - by Mrunal
    On an android device, I am connecting to a remote network using openvpn for performing service discovery. WORKING CASE: After the device is camped on 3g/4g and after connecting to remote network by openvpn, when the zeroconf browser is launched, I can see the mdns query packets being send through the tap0 interface resulting into rendering of services on the browser. From the tcpdump captured on the device, I can see that the mdns query packets are send to tap0 interface. tap0 ip: 192.168.11.200 Route table information: Destination Gateway Genmask Flags Metric Ref Use Iface 76.26.112.234 10.179.240.1 255.255.255.255 UGH 0 0 0 pdpbr1 10.179.240.1 * 255.255.255.255 UH 0 0 0 pdpbr1 32.1.72.136 * 255.255.255.255 UH 0 0 0 pdpbr0 10.179.240.0 * 255.255.255.0 U 0 0 0 pdpbr1 192.168.11.0 * 255.255.255.0 U 0 0 0 tap0 default 192.168.11.1 0.0.0.0 UG 0 0 0 tap0 NOT WORKING CASE: However, after switching on the wifi and connecting it to remote network, when the zeroconf browser is launched, instead of sending the mdns query packets to tap0 interface; these packets are being send to eth0 interface due to which we cannot see the services. From the tcpdump captured on the device, I can see that mdns query packets are send to eth0 interface. tap0 ip: 192.168.11.200 eth0 ip: 192.168.43.230 route table information: Destination Gateway Genmask Flags Metric Ref Use Iface 76.26.112.234 192.168.43.1 255.255.255.255 UGH 0 0 0 eth0 32.1.72.136 * 255.255.255.255 UH 0 0 0 pdpbr0 192.168.11.0 * 255.255.255.0 U 0 0 0 tap0 192.168.43.0 * 255.255.255.0 U 0 0 0 eth0 default 192.168.11.1 0.0.0.0 UG 0 0 0 tap0 In the above case, even though there is a default route for tap0, all the multicast packets are being routed through eth0. How is this possible? Has anyone observed a similar problem and it would be really helpful if you can help us to discover services through zeroconf browser after the device is connected to remote network via openvpn through wifi. Thank You Very much, Mrunal

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  • Connection string during installation

    - by anon2009
    Hi, I've been convinced to use windows setup files(msi) for the installation of my new windows forms application after I asked a question here and got some excellent answers (thank you all): http://serverfault.com/questions/97039/net-application-deployment Now i have a different question: My application will need to access a SQL Server to provide users with data, which means that the connection string must be stored in the client's app.config file. How should I handle this? During installation, the user enters the connection string to that database? How they get the connection string? In an email from the admin? What if the admin wants to use SQL authentication and need to put the user info at the connection string? So you know, the app will be sold via the internet, so I don't have any access to the admins or the network. Any suggestions? Thanks in advanced.

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  • Colored PS1 string

    - by Will Vousden
    Clarification: I want __foo to be executed each time the PS1 string is presented in the terminal, not when the PS1 string is constructed (hence its being in quotes). __foo contains logic that examines the current directory, so its execution must be deferred. I'm trying to use different colours in my Bash PS1 string from within a Bash function: LIGHTRED="\033[1;31m" LIGHTGREEN="\033[1;32m" RESET="\033[m" __foo () { # Do some stuff and genereate a string to echo in different colours: echo -n '\['$1'\]firstcolour \['$2'\]secondcolour' } PS1='$(__foo '$LIGHTRED' '$LIGHTGREEN')\['$RESET'\] \$' Essentially I want __foo to generate part of the PS1 in a bunch of different colours. My attempt doesn't seem to work, though; it produces the following output: -bash: 31m: command not found -bash: 32m: command not found \[]firstcolour \[\]secondcolour $ What gives, and how can I fix it?

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  • How to take search query and append modifers to the end of it

    - by Kimber
    This is a greasemonkey question. What I'm trying to do is modify an old google discussions script. What were wanting to do is be able to take the google search query and add modifiers to the end of it. Like this: search query: "superuser" modifiers: inurl:greasemonkey+question end result: "superuser" inurl:greasemonkey+question The old script creates a new div within the "hdtb_more_mn" element which is where you get the new discussions tab. However, since the "tbm=dsc" option to do a discussion search has died, this script no longer works. Hence the need to add modifiers to your searches. I tried to edit the script, but it appends the modifiers to the end of the url which includes "&client=firefox-a&hs=8uS&rls=org.mozilla:en-US:official". This means you're also searching for the above as well as your query, which doesn't work. I would like to be able to append the modifiers @ the end of the search querty, rather than the whole URL. I'm just not sure how to code it to where it adds the below "&tbm=" stuff within "discussionDiv.innerHTML" to the end of the query. The google search id seems to be, "gbqfq" for the search box, but I'm not sure how to add this id. Here is the old script // ==UserScript== // @name Add Back Google Discussions // @version 1.4 // @description Adds back the Discussion filters to Google Search // @include *://*.google.tld/search* // ==/UserScript== var url = location.href; if (url.indexOf('tbm=dsc') < 0) addFilterType('dsc', 'Discussions'); function addFilterType(val, name) { var searchType = document.getElementById('hdtb_more_mn'); var discussionDiv = document.createElement('DIV'); discussionDiv.className = 'hdtb_mitem'; discussionDiv.innerHTML = '<a class="q qs" href="'+ (url.replace(/&tbm=[^&]*/g,'') + '&tbm=' + val) +'">'+name+'</a>'; searchType.innerHTML += discussionDiv.outerHTML; } Thanks for any help, or suggestions on who to ask. Google Chrome has an extension for discussion searches, but FF doesn't seem to have one as of yet, which is why I'm trying to modify the above.

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  • VBA: Parse preceding numbers from string

    - by buttonsrtoys
    I need to parse into two substrings a string that always starts with numeric text followed by alphnumeric text. The strings can vary a bit, but not too much. Below are examples of incoming format and the strings I need: "00 10 50 Information to Bidders" ==> "00 10 50", "Information to Bidders" "001050 Information to Bidders" ==> "001050", "Information to Bidders" "00 10 50 - Information to Bidders" ==> "00 10 50", "Information to Bidders" "001050 -- Information to Bidders" ==> "001050", "Information to Bidders" I was hoping it would only be a half dozen lines of VBA, but my code is turning into a loop where I'm testing every character in the string to see where the changeover from numeric-only to non-numeric, then parsing the string based on the changeover location. Not a big deal, but messier than I was hoping for. Are there VBA functions that would eliminate the need to iterate through each string character?

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  • IPTables Reroute SSH based on Connection string?

    - by senrabdet
    We are using a cloud server (Debian Squeeze) where public ports on a public IP route traffic to internal servers. We are looking for a way to use IPTables and ssh where based on some part of the ssh connection string (or something along these lines) iptables will reroute the ssh connection to the "right" internal server. This would allow us to use one common public port, and then re-route ssh connections to individual servers. So, for example we hope to do something like the following: user issues ssh connection (public key encryption) such as ssh -X -v -p xxx [email protected] but maybe adds something into the string for iptables to use iptables uses some part of that string or some means to re-route the connection to an internal server using something like iptables -t nat -A PREROUTING ! -s xxx.xxx.xxx.0/24 -m tcp -p tcp --dport $EXTPORT -j DNAT --to-destination $HOST:$INTPORT ....where $HOST is the internal ip of a server, $EXTPORT is the common public facing port and $INTPORT is the internal server port. It appears that the "string" aspect of iptables does not do what we want. We can currently route based on the IP table syntax we're using, but rely on having a separate public port for each server and are hoping to use one common public port and then re-route to specific internal servers based on some part of the ssh connection string or some other means. Any suggestions? Thanks!

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  • How to increment the string value during run time without using dr.read() and store it in the oledb

    - by sameer
    Here is my code, everything is working fine the only problem is with the ReadData() method in which i want the string value to be increment i.e AM0001,AM0002,AM0003 etc. This is happening but only one time the value is getting increment to AM0001, the second time the same value i.e AM0001 is getting return. Due to this i am getting a error from oledb because of AM0001 is a primary key field. enter code here: class Jewellery : Connectionstr { string lmcode = null; public string LM_code { get { return lmcode;} set { lmcode = ReadData();} } string mname; public string M_Name { get { return mname; } set { mname = value;} } string desc; public string Desc { get { return desc; } set { desc = value; } } public string ReadData() { string jid = string.Empty; string displayString = string.Empty; String query = "select max(LM_code)from Master_Accounts"; Datamanager.RunExecuteReader(Constr,query); if (string.IsNullOrEmpty(jid)) { jid = "AM0000";//This string value has to increment at every time, but it is getting increment only one time. } int len = jid.Length; string split = jid.Substring(2, len - 2); int num = Convert.ToInt32(split); num++; displayString = jid.Substring(0, 2) + num.ToString("0000"); return displayString; } public void add() { String query ="insert into Master_Accounts values ('" + LM_code + "','" + M_Name + "','" + Desc + "')"; Datamanager.RunExecuteNonQuery(Constr , query); } Any help will be appreciated.

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  • Regular Expressions .NET

    - by Fosa
    I need a regular expression for some arguments that must match on a string. here it is... The string exists out of minimum 8 en maximum 20 characters. These characters of this string may be characters of the alfabet or special chars --With other words..all charachters except from the whitespaces In the complete string there must be atleast 1 number. The string cannot start with a number or an underscore The last 2 characters of the string must be identical, But it doenst matter if those last --identical characters are capital or non-capital (case insensitive) Must match all : +234567899 a_1de*Gg xy1Me*__ !41deF_hij2lMnopq3ss C234567890123$^67800 *5555555 sDF564zer"" !!!!!!!!!4!!!!!!!!!! abcdefghijklmnopq9ss May not match : Cannot be less then 8 or more then 20 chars: a_1+Eff B41def_hIJ2lmnopq3stt Cannot contain a whitespace: A_4 e*gg b41def_Hij2l nopq3ss Cannot start with a number or an underscore: __1+Eff 841DEf_hij2lmnopq3stt cannot end on 2 diffrent characters: a_1+eFg b41DEf_hij2lmnopq3st Cannot be without a number in the string: abCDefghijklmnopqrss abcdef+++dF !!!!!!!!!!!!!!!!!!!! ------------------------------------------------------ This is what I have so far...But I'm really breaking my head on this... If you Don't know the answer completely it's not a problem... I just want to get in the right direction ([^0-9_])(?=.*\d)(\S{8,20})(?i:[\S])\1

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  • Holding variables in memory, C++

    - by b-gen-jack-o-neill
    Today something strange came to my mind. When I want to hold some string in C (C++) the old way, without using string header, I just create array and store that string into it. But, I read that any variable definition in C in local scope of function ends up in pushing these values onto the stack. So, the string is actually 2* bigger than needed. Because first, the push instructions are located in memory, but then when they are executed (pushed onto the stack) another "copy" of the string is created. First the push instructions, than the stack space is used for one string. So, why is it this way? Why doesn't compiler just add the string (or other variables) to the program instead of creating them once again when executed? Yes, I know you cannot just have some data inside program block, but it could just be attached to the end of the program, with some jump instruction before. And than, we would just point to these data? Because they are stored in RAM when the program is executed. Thanks.

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  • Passing the CAML thru the EY of the NEEDL

    - by PointsToShare
    © 2011 By: Dov Trietsch. All rights reserved Passing the CAML thru the EY of the NEEDL Definitions: CAML (Collaborative Application Markup Language) is an XML based markup language used in Microsoft SharePoint technologies  Anonymous: A camel is a horse designed by committee  Dov Trietsch: A CAML is a HORS designed by Microsoft  I was advised against putting any Camel and Sphinx rhymes in here. Look it up in Google!  _____ Now that we have dispensed with the dromedary jokes (BTW, I have many more, but they are not fit to print!), here is an interesting problem and its solution.  We have built a list where the title must be kept unique so I needed to verify the existence (or absence) of a list item with a particular title. Two methods came to mind:  1: Span the list until the title is found (result = found) or until the list ends (result = not found). This is an algorithm of complexity O(N) and for long lists it is a performance sucker. 2: Use a CAML query instead. Here, for short list we’ll encounter some overhead, but because the query results in an SQL query on the content database, it is of complexity O(LogN), which is significantly better and scales perfectly. Obviously I decided to go with the latter and this is where the CAML s--t hit the fan.   A CAML query returns a SPListItemCollection and I simply checked its Count. If it was 0, the item did not already exist and it was safe to add a new item with the given title. Otherwise I cancelled the operation and warned the user. The trouble was that I always got a positive. Most of the time a false positive. The count was greater than 0 regardles of the title I checked (except when the list was empty, which happens only once). This was very disturbing indeed. To solve my immediate problem which was speedy delivery, I reverted to the “Span the list” approach, but the problem bugged me, so I wrote a little console app by which I tested and tweaked and tested, time and again, until I found the solution. Yes, one can pass the proverbial CAML thru the ey of the needle (e’s missing on purpose).  So here are my conclusions:  CAML that does not work:  Note: QT is my quote:  char QT = Convert.ToChar((int)34); string titleQuery = "<Query>><Where><Eq>"; titleQuery += "<FieldRef Name=" + QT + "Title" + QT + "/>"; titleQuery += "<Value Type=" + QT + "Text" + QT + ">" + uniqueID + "</Value></Eq></Where></Query>"; titleQuery += "<ViewFields><FieldRef Name=" + QT + "Title" + QT + "/></ViewFields>";  Why? Even though U2U generates it, the <Query> and </Query> tags do not belong in the query that you pass. Start your query with the <Where> clause.  Also the <ViewFiels> clause does not belong. I used this clause to limit the returned collection to a single column, and I still wish to do it. I’ll show how this is done a bit later.   When you use the <Query> </Query> tags in you query, it’s as if you did not specify the query at all. What you get is the all inclusive default query for the list. It returns evey column and every item. It is expensive for both server and network because it does all the extra processing and eats plenty of bandwidth.   Now, here is the CAML that works  string titleQuery = "<Where><Eq>"; titleQuery += "<FieldRef Name=" + QT + "Title" + QT + "/>"; titleQuery += "<Value Type=" + QT + "Text" + QT + ">" + uniqueID + "</Value></Eq></Where>";  You’ll also notice that inside the unusable <ViewFields> clause above, we have a <FieldRef> clause. This is what we pass to the SPQuery object. Here is how:  SPQuery query = new SPQuery(); query.Query = titleQuery; query.ViewFields = "<FieldRef Name=" + QT + "Title" + QT + "/>"; query.RowLimit = 1; SPListItemCollection col = masterList.GetItems(query);  Two thing to note: we enter the view fields into the SPQuery object and we also limited the number of rows that the query returns. The latter is not always done, but in an existence test, there is no point in returning hundreds of rows. The query will now return one item or none, which is all we need in order to verify the existence (or non-existence) of items. Limiting the number of columns and the number of rows is a great performance enhancer. That’s all folks!!

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  • Help needed on an SQL configuration problem.

    - by user321048
    I have been banging my head with this one more the two weeks, and still don't know what the problem is ( I can't narrow it down). The problem is the following. I have a solution with 3 project in it all written in c# and I with LINQ. One project is the main web site, the other is the data layer (communication with the database) and the third one is a custom little CMS. The problem is the following: On a hosting provider when I publish the site it all works perfectly, but this site was needed to be hosted on the client server so I needed to do that. But the problem is that I also needed to configure the client server, because they don't have an Administrator employed (I know, I know ;) ). For the first time I some how managed, to set it up but a problem appear. My main web site is working just as it suppose to be - it reads (communicates with) the database, but My CMS is not. It shows the first log in page, but after that when I try to log in it throws the following error: A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: TCP Provider, error: 0 - A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond.) Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. Exception Details: System.Data.SqlClient.SqlException: A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: TCP Provider, error: 0 - A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond.) Source Error: An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below. Stack Trace: [SqlException (0x80131904): A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: TCP Provider, error: 0 - A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond.)] System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection) +4846887 System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj) +194 System.Data.SqlClient.TdsParser.Connect(ServerInfo serverInfo, SqlInternalConnectionTds connHandler, Boolean ignoreSniOpenTimeout, Int64 timerExpire, Boolean encrypt, Boolean trustServerCert, Boolean integratedSecurity, SqlConnection owningObject) +4860189 System.Data.SqlClient.SqlInternalConnectionTds.AttemptOneLogin(ServerInfo serverInfo, String newPassword, Boolean ignoreSniOpenTimeout, Int64 timerExpire, SqlConnection owningObject) +90 System.Data.SqlClient.SqlInternalConnectionTds.LoginNoFailover(String host, String newPassword, Boolean redirectedUserInstance, SqlConnection owningObject, SqlConnectionString connectionOptions, Int64 timerStart) +342 System.Data.SqlClient.SqlInternalConnectionTds.OpenLoginEnlist(SqlConnection owningObject, SqlConnectionString connectionOptions, String newPassword, Boolean redirectedUserInstance) +221 System.Data.SqlClient.SqlInternalConnectionTds..ctor(DbConnectionPoolIdentity identity, SqlConnectionString connectionOptions, Object providerInfo, String newPassword, SqlConnection owningObject, Boolean redirectedUserInstance) +189 System.Data.SqlClient.SqlConnectionFactory.CreateConnection(DbConnectionOptions options, Object poolGroupProviderInfo, DbConnectionPool pool, DbConnection owningConnection) +185 System.Data.ProviderBase.DbConnectionFactory.CreatePooledConnection(DbConnection owningConnection, DbConnectionPool pool, DbConnectionOptions options) +31 System.Data.ProviderBase.DbConnectionPool.CreateObject(DbConnection owningObject) +433 System.Data.ProviderBase.DbConnectionPool.UserCreateRequest(DbConnection owningObject) +66 System.Data.ProviderBase.DbConnectionPool.GetConnection(DbConnection owningObject) +499 System.Data.ProviderBase.DbConnectionFactory.GetConnection(DbConnection owningConnection) +65 System.Data.ProviderBase.DbConnectionClosed.OpenConnection(DbConnection outerConnection, DbConnectionFactory connectionFactory) +117 System.Data.SqlClient.SqlConnection.Open() +122 System.Data.Linq.SqlClient.SqlConnectionManager.UseConnection(IConnectionUser user) +44 System.Data.Linq.SqlClient.SqlProvider.get_IsSqlCe() +45 System.Data.Linq.SqlClient.SqlProvider.InitializeProviderMode() +20 System.Data.Linq.SqlClient.SqlProvider.System.Data.Linq.Provider.IProvider.Execute(Expression query) +57 System.Data.Linq.DataQuery`1.System.Linq.IQueryProvider.Execute(Expression expression) +23 System.Linq.Queryable.Count(IQueryable`1 source) +240 CMS.Security.UserProfile.LoginUser() in C:\Documents and Settings\Dimitar\Desktop\New Mepso Final 08_04\CMS\Classes\UserProfile.cs:132 CMS.Default.Login1_Authenticate(Object sender, AuthenticateEventArgs e) in C:\Documents and Settings\Dimitar\Desktop\New Mepso Final 08_04\CMS\Default.aspx.cs:37 System.Web.UI.WebControls.Login.OnAuthenticate(AuthenticateEventArgs e) +108 System.Web.UI.WebControls.Login.AttemptLogin() +115 System.Web.UI.WebControls.Login.OnBubbleEvent(Object source, EventArgs e) +101 System.Web.UI.Control.RaiseBubbleEvent(Object source, EventArgs args) +37 System.Web.UI.WebControls.Button.OnCommand(CommandEventArgs e) +118 System.Web.UI.WebControls.Button.RaisePostBackEvent(String eventArgument) +166 System.Web.UI.WebControls.Button.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument) +10 System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) +13 System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData) +36 System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +1565 Maybe this is a dumb question, but I cannot find the root of the problem, let alone the solution. So far I have tried the following: -setting time out on connection string to a higher value -configuration and after that turning off server firewall -checking the connection string over and over again (they are the same for all three projects and are saved in web.config) Important notes: I have tried executing the project from VS2008 with a connection string to the same database and the results are the same. That's why I think the problem is the SQL Server 2005 and not the IIS7. Any bit of information is more then welcomed.

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  • What are good design practices when working with Entity Framework

    - by AD
    This will apply mostly for an asp.net application where the data is not accessed via soa. Meaning that you get access to the objects loaded from the framework, not Transfer Objects, although some recommendation still apply. This is a community post, so please add to it as you see fit. Applies to: Entity Framework 1.0 shipped with Visual Studio 2008 sp1. Why pick EF in the first place? Considering it is a young technology with plenty of problems (see below), it may be a hard sell to get on the EF bandwagon for your project. However, it is the technology Microsoft is pushing (at the expense of Linq2Sql, which is a subset of EF). In addition, you may not be satisfied with NHibernate or other solutions out there. Whatever the reasons, there are people out there (including me) working with EF and life is not bad.make you think. EF and inheritance The first big subject is inheritance. EF does support mapping for inherited classes that are persisted in 2 ways: table per class and table the hierarchy. The modeling is easy and there are no programming issues with that part. (The following applies to table per class model as I don't have experience with table per hierarchy, which is, anyway, limited.) The real problem comes when you are trying to run queries that include one or many objects that are part of an inheritance tree: the generated sql is incredibly awful, takes a long time to get parsed by the EF and takes a long time to execute as well. This is a real show stopper. Enough that EF should probably not be used with inheritance or as little as possible. Here is an example of how bad it was. My EF model had ~30 classes, ~10 of which were part of an inheritance tree. On running a query to get one item from the Base class, something as simple as Base.Get(id), the generated SQL was over 50,000 characters. Then when you are trying to return some Associations, it degenerates even more, going as far as throwing SQL exceptions about not being able to query more than 256 tables at once. Ok, this is bad, EF concept is to allow you to create your object structure without (or with as little as possible) consideration on the actual database implementation of your table. It completely fails at this. So, recommendations? Avoid inheritance if you can, the performance will be so much better. Use it sparingly where you have to. In my opinion, this makes EF a glorified sql-generation tool for querying, but there are still advantages to using it. And ways to implement mechanism that are similar to inheritance. Bypassing inheritance with Interfaces First thing to know with trying to get some kind of inheritance going with EF is that you cannot assign a non-EF-modeled class a base class. Don't even try it, it will get overwritten by the modeler. So what to do? You can use interfaces to enforce that classes implement some functionality. For example here is a IEntity interface that allow you to define Associations between EF entities where you don't know at design time what the type of the entity would be. public enum EntityTypes{ Unknown = -1, Dog = 0, Cat } public interface IEntity { int EntityID { get; } string Name { get; } Type EntityType { get; } } public partial class Dog : IEntity { // implement EntityID and Name which could actually be fields // from your EF model Type EntityType{ get{ return EntityTypes.Dog; } } } Using this IEntity, you can then work with undefined associations in other classes // lets take a class that you defined in your model. // that class has a mapping to the columns: PetID, PetType public partial class Person { public IEntity GetPet() { return IEntityController.Get(PetID,PetType); } } which makes use of some extension functions: public class IEntityController { static public IEntity Get(int id, EntityTypes type) { switch (type) { case EntityTypes.Dog: return Dog.Get(id); case EntityTypes.Cat: return Cat.Get(id); default: throw new Exception("Invalid EntityType"); } } } Not as neat as having plain inheritance, particularly considering you have to store the PetType in an extra database field, but considering the performance gains, I would not look back. It also cannot model one-to-many, many-to-many relationship, but with creative uses of 'Union' it could be made to work. Finally, it creates the side effet of loading data in a property/function of the object, which you need to be careful about. Using a clear naming convention like GetXYZ() helps in that regards. Compiled Queries Entity Framework performance is not as good as direct database access with ADO (obviously) or Linq2SQL. There are ways to improve it however, one of which is compiling your queries. The performance of a compiled query is similar to Linq2Sql. What is a compiled query? It is simply a query for which you tell the framework to keep the parsed tree in memory so it doesn't need to be regenerated the next time you run it. So the next run, you will save the time it takes to parse the tree. Do not discount that as it is a very costly operation that gets even worse with more complex queries. There are 2 ways to compile a query: creating an ObjectQuery with EntitySQL and using CompiledQuery.Compile() function. (Note that by using an EntityDataSource in your page, you will in fact be using ObjectQuery with EntitySQL, so that gets compiled and cached). An aside here in case you don't know what EntitySQL is. It is a string-based way of writing queries against the EF. Here is an example: "select value dog from Entities.DogSet as dog where dog.ID = @ID". The syntax is pretty similar to SQL syntax. You can also do pretty complex object manipulation, which is well explained [here][1]. Ok, so here is how to do it using ObjectQuery< string query = "select value dog " + "from Entities.DogSet as dog " + "where dog.ID = @ID"; ObjectQuery<Dog> oQuery = new ObjectQuery<Dog>(query, EntityContext.Instance)); oQuery.Parameters.Add(new ObjectParameter("ID", id)); oQuery.EnablePlanCaching = true; return oQuery.FirstOrDefault(); The first time you run this query, the framework will generate the expression tree and keep it in memory. So the next time it gets executed, you will save on that costly step. In that example EnablePlanCaching = true, which is unnecessary since that is the default option. The other way to compile a query for later use is the CompiledQuery.Compile method. This uses a delegate: static readonly Func<Entities, int, Dog> query_GetDog = CompiledQuery.Compile<Entities, int, Dog>((ctx, id) => ctx.DogSet.FirstOrDefault(it => it.ID == id)); or using linq static readonly Func<Entities, int, Dog> query_GetDog = CompiledQuery.Compile<Entities, int, Dog>((ctx, id) => (from dog in ctx.DogSet where dog.ID == id select dog).FirstOrDefault()); to call the query: query_GetDog.Invoke( YourContext, id ); The advantage of CompiledQuery is that the syntax of your query is checked at compile time, where as EntitySQL is not. However, there are other consideration... Includes Lets say you want to have the data for the dog owner to be returned by the query to avoid making 2 calls to the database. Easy to do, right? EntitySQL string query = "select value dog " + "from Entities.DogSet as dog " + "where dog.ID = @ID"; ObjectQuery<Dog> oQuery = new ObjectQuery<Dog>(query, EntityContext.Instance)).Include("Owner"); oQuery.Parameters.Add(new ObjectParameter("ID", id)); oQuery.EnablePlanCaching = true; return oQuery.FirstOrDefault(); CompiledQuery static readonly Func<Entities, int, Dog> query_GetDog = CompiledQuery.Compile<Entities, int, Dog>((ctx, id) => (from dog in ctx.DogSet.Include("Owner") where dog.ID == id select dog).FirstOrDefault()); Now, what if you want to have the Include parametrized? What I mean is that you want to have a single Get() function that is called from different pages that care about different relationships for the dog. One cares about the Owner, another about his FavoriteFood, another about his FavotireToy and so on. Basicly, you want to tell the query which associations to load. It is easy to do with EntitySQL public Dog Get(int id, string include) { string query = "select value dog " + "from Entities.DogSet as dog " + "where dog.ID = @ID"; ObjectQuery<Dog> oQuery = new ObjectQuery<Dog>(query, EntityContext.Instance)) .IncludeMany(include); oQuery.Parameters.Add(new ObjectParameter("ID", id)); oQuery.EnablePlanCaching = true; return oQuery.FirstOrDefault(); } The include simply uses the passed string. Easy enough. Note that it is possible to improve on the Include(string) function (that accepts only a single path) with an IncludeMany(string) that will let you pass a string of comma-separated associations to load. Look further in the extension section for this function. If we try to do it with CompiledQuery however, we run into numerous problems: The obvious static readonly Func<Entities, int, string, Dog> query_GetDog = CompiledQuery.Compile<Entities, int, string, Dog>((ctx, id, include) => (from dog in ctx.DogSet.Include(include) where dog.ID == id select dog).FirstOrDefault()); will choke when called with: query_GetDog.Invoke( YourContext, id, "Owner,FavoriteFood" ); Because, as mentionned above, Include() only wants to see a single path in the string and here we are giving it 2: "Owner" and "FavoriteFood" (which is not to be confused with "Owner.FavoriteFood"!). Then, let's use IncludeMany(), which is an extension function static readonly Func<Entities, int, string, Dog> query_GetDog = CompiledQuery.Compile<Entities, int, string, Dog>((ctx, id, include) => (from dog in ctx.DogSet.IncludeMany(include) where dog.ID == id select dog).FirstOrDefault()); Wrong again, this time it is because the EF cannot parse IncludeMany because it is not part of the functions that is recognizes: it is an extension. Ok, so you want to pass an arbitrary number of paths to your function and Includes() only takes a single one. What to do? You could decide that you will never ever need more than, say 20 Includes, and pass each separated strings in a struct to CompiledQuery. But now the query looks like this: from dog in ctx.DogSet.Include(include1).Include(include2).Include(include3) .Include(include4).Include(include5).Include(include6) .[...].Include(include19).Include(include20) where dog.ID == id select dog which is awful as well. Ok, then, but wait a minute. Can't we return an ObjectQuery< with CompiledQuery? Then set the includes on that? Well, that what I would have thought so as well: static readonly Func<Entities, int, ObjectQuery<Dog>> query_GetDog = CompiledQuery.Compile<Entities, int, string, ObjectQuery<Dog>>((ctx, id) => (ObjectQuery<Dog>)(from dog in ctx.DogSet where dog.ID == id select dog)); public Dog GetDog( int id, string include ) { ObjectQuery<Dog> oQuery = query_GetDog(id); oQuery = oQuery.IncludeMany(include); return oQuery.FirstOrDefault; } That should have worked, except that when you call IncludeMany (or Include, Where, OrderBy...) you invalidate the cached compiled query because it is an entirely new one now! So, the expression tree needs to be reparsed and you get that performance hit again. So what is the solution? You simply cannot use CompiledQueries with parametrized Includes. Use EntitySQL instead. This doesn't mean that there aren't uses for CompiledQueries. It is great for localized queries that will always be called in the same context. Ideally CompiledQuery should always be used because the syntax is checked at compile time, but due to limitation, that's not possible. An example of use would be: you may want to have a page that queries which two dogs have the same favorite food, which is a bit narrow for a BusinessLayer function, so you put it in your page and know exactly what type of includes are required. Passing more than 3 parameters to a CompiledQuery Func is limited to 5 parameters, of which the last one is the return type and the first one is your Entities object from the model. So that leaves you with 3 parameters. A pitance, but it can be improved on very easily. public struct MyParams { public string param1; public int param2; public DateTime param3; } static readonly Func<Entities, MyParams, IEnumerable<Dog>> query_GetDog = CompiledQuery.Compile<Entities, MyParams, IEnumerable<Dog>>((ctx, myParams) => from dog in ctx.DogSet where dog.Age == myParams.param2 && dog.Name == myParams.param1 and dog.BirthDate > myParams.param3 select dog); public List<Dog> GetSomeDogs( int age, string Name, DateTime birthDate ) { MyParams myParams = new MyParams(); myParams.param1 = name; myParams.param2 = age; myParams.param3 = birthDate; return query_GetDog(YourContext,myParams).ToList(); } Return Types (this does not apply to EntitySQL queries as they aren't compiled at the same time during execution as the CompiledQuery method) Working with Linq, you usually don't force the execution of the query until the very last moment, in case some other functions downstream wants to change the query in some way: static readonly Func<Entities, int, string, IEnumerable<Dog>> query_GetDog = CompiledQuery.Compile<Entities, int, string, IEnumerable<Dog>>((ctx, age, name) => from dog in ctx.DogSet where dog.Age == age && dog.Name == name select dog); public IEnumerable<Dog> GetSomeDogs( int age, string name ) { return query_GetDog(YourContext,age,name); } public void DataBindStuff() { IEnumerable<Dog> dogs = GetSomeDogs(4,"Bud"); // but I want the dogs ordered by BirthDate gridView.DataSource = dogs.OrderBy( it => it.BirthDate ); } What is going to happen here? By still playing with the original ObjectQuery (that is the actual return type of the Linq statement, which implements IEnumerable), it will invalidate the compiled query and be force to re-parse. So, the rule of thumb is to return a List< of objects instead. static readonly Func<Entities, int, string, IEnumerable<Dog>> query_GetDog = CompiledQuery.Compile<Entities, int, string, IEnumerable<Dog>>((ctx, age, name) => from dog in ctx.DogSet where dog.Age == age && dog.Name == name select dog); public List<Dog> GetSomeDogs( int age, string name ) { return query_GetDog(YourContext,age,name).ToList(); //<== change here } public void DataBindStuff() { List<Dog> dogs = GetSomeDogs(4,"Bud"); // but I want the dogs ordered by BirthDate gridView.DataSource = dogs.OrderBy( it => it.BirthDate ); } When you call ToList(), the query gets executed as per the compiled query and then, later, the OrderBy is executed against the objects in memory. It may be a little bit slower, but I'm not even sure. One sure thing is that you have no worries about mis-handling the ObjectQuery and invalidating the compiled query plan. Once again, that is not a blanket statement. ToList() is a defensive programming trick, but if you have a valid reason not to use ToList(), go ahead. There are many cases in which you would want to refine the query before executing it. Performance What is the performance impact of compiling a query? It can actually be fairly large. A rule of thumb is that compiling and caching the query for reuse takes at least double the time of simply executing it without caching. For complex queries (read inherirante), I have seen upwards to 10 seconds. So, the first time a pre-compiled query gets called, you get a performance hit. After that first hit, performance is noticeably better than the same non-pre-compiled query. Practically the same as Linq2Sql When you load a page with pre-compiled queries the first time you will get a hit. It will load in maybe 5-15 seconds (obviously more than one pre-compiled queries will end up being called), while subsequent loads will take less than 300ms. Dramatic difference, and it is up to you to decide if it is ok for your first user to take a hit or you want a script to call your pages to force a compilation of the queries. Can this query be cached? { Dog dog = from dog in YourContext.DogSet where dog.ID == id select dog; } No, ad-hoc Linq queries are not cached and you will incur the cost of generating the tree every single time you call it. Parametrized Queries Most search capabilities involve heavily parametrized queries. There are even libraries available that will let you build a parametrized query out of lamba expressions. The problem is that you cannot use pre-compiled queries with those. One way around that is to map out all the possible criteria in the query and flag which one you want to use: public struct MyParams { public string name; public bool checkName; public int age; public bool checkAge; } static readonly Func<Entities, MyParams, IEnumerable<Dog>> query_GetDog = CompiledQuery.Compile<Entities, MyParams, IEnumerable<Dog>>((ctx, myParams) => from dog in ctx.DogSet where (myParams.checkAge == true && dog.Age == myParams.age) && (myParams.checkName == true && dog.Name == myParams.name ) select dog); protected List<Dog> GetSomeDogs() { MyParams myParams = new MyParams(); myParams.name = "Bud"; myParams.checkName = true; myParams.age = 0; myParams.checkAge = false; return query_GetDog(YourContext,myParams).ToList(); } The advantage here is that you get all the benifits of a pre-compiled quert. The disadvantages are that you most likely will end up with a where clause that is pretty difficult to maintain, that you will incur a bigger penalty for pre-compiling the query and that each query you run is not as efficient as it could be (particularly with joins thrown in). Another way is to build an EntitySQL query piece by piece, like we all did with SQL. protected List<Dod> GetSomeDogs( string name, int age) { string query = "select value dog from Entities.DogSet where 1 = 1 "; if( !String.IsNullOrEmpty(name) ) query = query + " and dog.Name == @Name "; if( age > 0 ) query = query + " and dog.Age == @Age "; ObjectQuery<Dog> oQuery = new ObjectQuery<Dog>( query, YourContext ); if( !String.IsNullOrEmpty(name) ) oQuery.Parameters.Add( new ObjectParameter( "Name", name ) ); if( age > 0 ) oQuery.Parameters.Add( new ObjectParameter( "Age", age ) ); return oQuery.ToList(); } Here the problems are: - there is no syntax checking during compilation - each different combination of parameters generate a different query which will need to be pre-compiled when it is first run. In this case, there are only 4 different possible queries (no params, age-only, name-only and both params), but you can see that there can be way more with a normal world search. - Noone likes to concatenate strings! Another option is to query a large subset of the data and then narrow it down in memory. This is particularly useful if you are working with a definite subset of the data, like all the dogs in a city. You know there are a lot but you also know there aren't that many... so your CityDog search page can load all the dogs for the city in memory, which is a single pre-compiled query and then refine the results protected List<Dod> GetSomeDogs( string name, int age, string city) { string query = "select value dog from Entities.DogSet where dog.Owner.Address.City == @City "; ObjectQuery<Dog> oQuery = new ObjectQuery<Dog>( query, YourContext ); oQuery.Parameters.Add( new ObjectParameter( "City", city ) ); List<Dog> dogs = oQuery.ToList(); if( !String.IsNullOrEmpty(name) ) dogs = dogs.Where( it => it.Name == name ); if( age > 0 ) dogs = dogs.Where( it => it.Age == age ); return dogs; } It is particularly useful when you start displaying all the data then allow for filtering. Problems: - Could lead to serious data transfer if you are not careful about your subset. - You can only filter on the data that you returned. It means that if you don't return the Dog.Owner association, you will not be able to filter on the Dog.Owner.Name So what is the best solution? There isn't any. You need to pick the solution that works best for you and your problem: - Use lambda-based query building when you don't care about pre-compiling your queries. - Use fully-defined pre-compiled Linq query when your object structure is not too complex. - Use EntitySQL/string concatenation when the structure could be complex and when the possible number of different resulting queries are small (which means fewer pre-compilation hits). - Use in-memory filtering when you are working with a smallish subset of the data or when you had to fetch all of the data on the data at first anyway (if the performance is fine with all the data, then filtering in memory will not cause any time to be spent in the db). Singleton access The best way to deal with your context and entities accross all your pages is to use the singleton pattern: public sealed class YourContext { private const string instanceKey = "On3GoModelKey"; YourContext(){} public static YourEntities Instance { get { HttpContext context = HttpContext.Current; if( context == null ) return Nested.instance; if (context.Items[instanceKey] == null) { On3GoEntities entity = new On3GoEntities(); context.Items[instanceKey] = entity; } return (YourEntities)context.Items[instanceKey]; } } class Nested { // Explicit static constructor to tell C# compiler // not to mark type as beforefieldinit static Nested() { } internal static readonly YourEntities instance = new YourEntities(); } } NoTracking, is it worth it? When executing a query, you can tell the framework to track the objects it will return or not. What does it mean? With tracking enabled (the default option), the framework will track what is going on with the object (has it been modified? Created? Deleted?) and will also link objects together, when further queries are made from the database, which is what is of interest here. For example, lets assume that Dog with ID == 2 has an owner which ID == 10. Dog dog = (from dog in YourContext.DogSet where dog.ID == 2 select dog).FirstOrDefault(); //dog.OwnerReference.IsLoaded == false; Person owner = (from o in YourContext.PersonSet where o.ID == 10 select dog).FirstOrDefault(); //dog.OwnerReference.IsLoaded == true; If we were to do the same with no tracking, the result would be different. ObjectQuery<Dog> oDogQuery = (ObjectQuery<Dog>) (from dog in YourContext.DogSet where dog.ID == 2 select dog); oDogQuery.MergeOption = MergeOption.NoTracking; Dog dog = oDogQuery.FirstOrDefault(); //dog.OwnerReference.IsLoaded == false; ObjectQuery<Person> oPersonQuery = (ObjectQuery<Person>) (from o in YourContext.PersonSet where o.ID == 10 select o); oPersonQuery.MergeOption = MergeOption.NoTracking; Owner owner = oPersonQuery.FirstOrDefault(); //dog.OwnerReference.IsLoaded == false; Tracking is very useful and in a perfect world without performance issue, it would always be on. But in this world, there is a price for it, in terms of performance. So, should you use NoTracking to speed things up? It depends on what you are planning to use the data for. Is there any chance that the data your query with NoTracking can be used to make update/insert/delete in the database? If so, don't use NoTracking because associations are not tracked and will causes exceptions to be thrown. In a page where there are absolutly no updates to the database, you can use NoTracking. Mixing tracking and NoTracking is possible, but it requires you to be extra careful with updates/inserts/deletes. The problem is that if you mix then you risk having the framework trying to Attach() a NoTracking object to the context where another copy of the same object exist with tracking on. Basicly, what I am saying is that Dog dog1 = (from dog in YourContext.DogSet where dog.ID == 2).FirstOrDefault(); ObjectQuery<Dog> oDogQuery = (ObjectQuery<Dog>) (from dog in YourContext.DogSet where dog.ID == 2 select dog); oDogQuery.MergeOption = MergeOption.NoTracking; Dog dog2 = oDogQuery.FirstOrDefault(); dog1 and dog2 are 2 different objects, one tracked and one not. Using the detached object in an update/insert will force an Attach() that will say "Wait a minute, I do already have an object here with the same database key. Fail". And when you Attach() one object, all of its hierarchy gets attached as well, causing problems everywhere. Be extra careful. How much faster is it with NoTracking It depends on the queries. Some are much more succeptible to tracking than other. I don't have a fast an easy rule for it, but it helps. So I should use NoTracking everywhere then? Not exactly. There are some advantages to tracking object. The first one is that the object is cached, so subsequent call for that object will not hit the database. That cache is only valid for the lifetime of the YourEntities object, which, if you use the singleton code above, is the same as the page lifetime. One page request == one YourEntity object. So for multiple calls for the same object, it will load only once per page request. (Other caching mechanism could extend that). What happens when you are using NoTracking and try to load the same object multiple times? The database will be queried each time, so there is an impact there. How often do/should you call for the same object during a single page request? As little as possible of course, but it does happens. Also remember the piece above about having the associations connected automatically for your? You don't have that with NoTracking, so if you load your data in multiple batches, you will not have a link to between them: ObjectQuery<Dog> oDogQuery = (ObjectQuery<Dog>)(from dog in YourContext.DogSet select dog); oDogQuery.MergeOption = MergeOption.NoTracking; List<Dog> dogs = oDogQuery.ToList(); ObjectQuery<Person> oPersonQuery = (ObjectQuery<Person>)(from o in YourContext.PersonSet select o); oPersonQuery.MergeOption = MergeOption.NoTracking; List<Person> owners = oPersonQuery.ToList(); In this case, no dog will have its .Owner property set. Some things to keep in mind when you are trying to optimize the performance. No lazy loading, what am I to do? This can be seen as a blessing in disguise. Of course it is annoying to load everything manually. However, it decreases the number of calls to the db and forces you to think about when you should load data. The more you can load in one database call the better. That was always true, but it is enforced now with this 'feature' of EF. Of course, you can call if( !ObjectReference.IsLoaded ) ObjectReference.Load(); if you want to, but a better practice is to force the framework to load the objects you know you will need in one shot. This is where the discussion about parametrized Includes begins to make sense. Lets say you have you Dog object public class Dog { public Dog Get(int id) { return YourContext.DogSet.FirstOrDefault(it => it.ID == id ); } } This is the type of function you work with all the time. It gets called from all over the place and once you have that Dog object, you will do very different things to it in different functions. First, it should be pre-compiled, because you will call that very often. Second, each different pages will want to have access to a different subset of the Dog data. Some will want the Owner, some the FavoriteToy, etc. Of course, you could call Load() for each reference you need anytime you need one. But that will generate a call to the database each time. Bad idea. So instead, each page will ask for the data it wants to see when it first request for the Dog object: static public Dog Get(int id) { return GetDog(entity,"");} static public Dog Get(int id, string includePath) { string query = "select value o " + " from YourEntities.DogSet as o " +

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  • Jsf RichFaces autocomplete : get the String for autocomplete- method()

    - by JavaNullPointer
    Part of my xhmtl-Page: <rich:autocomplete autocompleteMethod="#{autocompletMit.searchbyName()}" mode="cachedAjax" fetchValue="#{controller.mitarbeiter.mitarbeiterName}" autocompleteList="#{autocompletMit.autocompleteList}" minChars="1" autofill="true" var="it" > <h:outputText value="#{it.mitarbeiterName}" style="font-weight:bold"/> </rich:autocomplete> Bean for my Autocomplete: @ManagedBean(name = "autocompletMit") @RequestScoped public class AutoCompleteMitarbeiter implements Serializable { @EJB private Transaktionssteuerung transakt; private List<String> autocompleteList = new ArrayList<String>(); String nameSearch; public List<String> searchbyName(Object o) { String test = (String) o; //always get here a NullPointerException List<Mitarbeiter> alleMitarbeiter = transakt.alleMitarbeiter(); for (Iterator<Mitarbeiter> it = alleMitarbeiter.iterator(); it.hasNext();) { if (it.next().getMitarbeiterName().startsWith(test)) { autocompleteList.add(it.next().getMitarbeiterName()); } } return autocompleteList; } I always get a NullPointerException for String test = (String) o; I dont know how to get the StringInput correctly from </rich:autocomplete>-Input....

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  • Java anagram recursion List<List<String>> only storing empty lists<Strings>

    - by Riff Rafffer
    Hi In this recursion method i am trying to find all anagrams and add it to a List but what happens when i run this code is it just returns alot of empty Lists. private List<List<String>> findAnagrams(LetterInventory words, ArrayList<String> anagram, int max, Map<String, LetterInventory> smallDict, int level, List<List<String>> result) { ArrayList<String> solvedWord = new ArrayList<String>(); LetterInventory shell; LetterInventory shell2; if (level < max || max == 0) { Iterator<String> it = smallDict.keySet().iterator(); while (it.hasNext()) { String k = it.next(); shell = new LetterInventory(k); shell2 = words; if (shell2.subtract(shell) != null) { anagram.add(k); shell2 = words.subtract(shell); if (shell2.isEmpty()) { //System.out.println(anagram.toString()); it prints off fine here result.add(anagram); // but doesnt add here } else findAnagrams(shell2, anagram, max, smallDict, level + 1, result); anagram.remove(anagram.size()-1); } } } return results; }

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