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  • Strange PHP reference bug

    - by Roland Soós
    Hello, I have a really strange bug with my PHP code. I have a recursive code which build up a menu tree with object and one of my customers server can't make it work. Contructor: function Menu(&$menus, &$keys , &$parent, &$menu){ ... if($keys === NULL){ $keys = array_keys($menus); } ... for($x = 0; $x < count($keys); $x++) { var_dump($keys); $menu = $menus[$keys[$x]]; var_dump($keys); if($this->id == $menu->pid){ $keys[$x] = NULL; $this->submenus[] = new Menu($menus, $keys, $this, $menu); } } First var_dump give me back the array, the second give back the first element of $menus. Do you have any idea what causes this? PHP version 5.2.3

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  • Howw to add new value with generic Repository if there are foreign keys (EF-4)?

    - by Phsika
    i try to write a kind of generic repository to add method. Everything is ok to add but I have table which is related with two tables with FOREIGN KEY.But Not working because of foreign key public class DomainRepository<TModel> : IDomainRepository<TModel> where TModel : class { #region IDomainRepository<T> Members private ObjectContext _context; private IObjectSet<TModel> _objectSet; public DomainRepository() { } public DomainRepository(ObjectContext context) { _context = context; _objectSet = _context.CreateObjectSet<TModel>(); } //do something..... public TModel Add<TModel>(TModel entity) where TModel : IEntityWithKey { EntityKey key; object originalItem; key = _context.CreateEntityKey(entity.GetType().Name, entity); _context.AddObject(key.EntitySetName, entity); _context.SaveChanges(); return entity; } //do something..... } Calling REPOSITORY: //insert-update-delete public partial class AddtoTables { public table3 Add(int TaskId, int RefAircraftsId) { using (DomainRepository<table3> repTask = new DomainRepository<table3>(new TaskEntities())) { return repTask.Add<table3>(new table3() { TaskId = TaskId, TaskRefAircraftsID = RefAircraftsId }); } } } How to add a new value if this table includes foreign key relation

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  • Which design better when use foreign key instead of a string to store a list of id

    - by Kien Thanh
    I'm building online examination system. I have designed to table, Question and GeneralExam. The table GeneralExam contains info about the exam like name, description, duration,... Now I would like to design table GeneralQuestion, it will contain the ids of questions belongs to a general exam. Currently, I have two ideas to design GeneralQuestion table: It will have two columns: general_exam_id, question_id. It will have two columns: general_exam_id, list_question_ids (string/text). I would like to know which designing is better, or pros and cons of each designing. I'm using Postgresql database.

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  • How can we integrate use of a foreign language into an internship?

    - by ChrisRamakers
    We have a few interns here that have orders from college to integrate speaking, reading, and writing French into their internship. All of them are working on developing their own web application, and I'm wondering how we can integrate French into their projects. Here are some things I've come up with: Translate the whole project front-end to French Write French documentation for the project Promote the application in a French community Speak French (exclusively?) to our project managers Any other ideas or suggestions? Does anyone else have experience with this?

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  • Redesigning foreign website for my portfolio and offer it?

    - by BeatMe
    Hi, I've had an interest in web design for a long time and am constantly trying to learn something new. I do not have any references in my portfolio, but would like to start freelancing. Is it bad practice to redesign a website from a local company and use it for my portfolio? Do I infringe any copyright? What if I offer the redesign to the company? Has someone done this before? If so, share your experiences.

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  • Redesigning foreign website for my portfolio and offer it?

    - by BeatMe
    I've had an interest in web design for a long time and am constantly trying to learn something new. I do not have any references in my portfolio, but would like to start freelancing. Is it bad practice to redesign a website from a local company and use it for my portfolio? Do I infringe any copyright? What if I offer the redesign to the company? Has someone done this before? If so, share your experiences.

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  • How can I program the function keys on my MacBook?

    - by mrdatabase
    I'd like to assign basic tasks to the function keys (or other keys if it's easier) on my MacBook. For example I'd like the following to happen when F1 (or whatever key) is pressed: Launch Safari Open a new window Navigate to some specified site Another example could be: Launch Xcode Open some specific project I've experimented with the Automator for things like re-naming dozens of files in a particular directory but I don't know where to start for the above examples.

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  • Do I need to recreate statistics if I had to drop them to add a foreign key

    - by Adam J.R. Erickson
    I have a database which had all it's foreign-key relationships dropped at some unknown time in the past (don't ask). I have an old copy of the database which isn't good to restore from, but the schema has the relationships. I'm working from that to create a script to restore the keys. In updating the tables, I've had to drop statistics from several tables. Do I need to manually recreate those, or can I just run the statistics update procedure when all the tables are updated?

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  • Implementation of ZipCrypto / Zip 2.0 encryption in java

    - by gomesla
    I'm trying o implement the zipcrypto / zip 2.0 encryption algoritm to deal with encrypted zip files as discussed in http://www.pkware.com/documents/casestudies/APPNOTE.TXT I believe I've followed the specs but just can't seem to get it working. I'm fairly sure the issue has to do with my interpretation of the crc algorithm. The documentation states CRC-32: (4 bytes) The CRC-32 algorithm was generously contributed by David Schwaderer and can be found in his excellent book "C Programmers Guide to NetBIOS" published by Howard W. Sams & Co. Inc. The 'magic number' for the CRC is 0xdebb20e3. The proper CRC pre and post conditioning is used, meaning that the CRC register is pre-conditioned with all ones (a starting value of 0xffffffff) and the value is post-conditioned by taking the one's complement of the CRC residual. Here is the snippet that I'm using for the crc32 public class PKZIPCRC32 { private static final int CRC32_POLYNOMIAL = 0xdebb20e3; private int crc = 0xffffffff; private int CRCTable[]; public PKZIPCRC32() { buildCRCTable(); } private void buildCRCTable() { int i, j; CRCTable = new int[256]; for (i = 0; i <= 255; i++) { crc = i; for (j = 8; j > 0; j--) if ((crc & 1) == 1) crc = (crc >>> 1) ^ CRC32_POLYNOMIAL; else crc >>>= 1; CRCTable[i] = crc; } } private int crc32(byte buffer[], int start, int count, int lastcrc) { int temp1, temp2; int i = start; crc = lastcrc; while (count-- != 0) { temp1 = crc >>> 8; temp2 = CRCTable[(crc ^ buffer[i++]) & 0xFF]; crc = temp1 ^ temp2; } return crc; } public int crc32(int crc, byte buffer) { return crc32(new byte[] { buffer }, 0, 1, crc); } } Below is my complete code. Can anyone see what I'm doing wrong. package org.apache.commons.compress.archivers.zip; import java.io.IOException; import java.io.InputStream; public class ZipCryptoInputStream extends InputStream { public class PKZIPCRC32 { private static final int CRC32_POLYNOMIAL = 0xdebb20e3; private int crc = 0xffffffff; private int CRCTable[]; public PKZIPCRC32() { buildCRCTable(); } private void buildCRCTable() { int i, j; CRCTable = new int[256]; for (i = 0; i <= 255; i++) { crc = i; for (j = 8; j > 0; j--) if ((crc & 1) == 1) crc = (crc >>> 1) ^ CRC32_POLYNOMIAL; else crc >>>= 1; CRCTable[i] = crc; } } private int crc32(byte buffer[], int start, int count, int lastcrc) { int temp1, temp2; int i = start; crc = lastcrc; while (count-- != 0) { temp1 = crc >>> 8; temp2 = CRCTable[(crc ^ buffer[i++]) & 0xFF]; crc = temp1 ^ temp2; } return crc; } public int crc32(int crc, byte buffer) { return crc32(new byte[] { buffer }, 0, 1, crc); } } private static final long ENCRYPTION_KEY_1 = 0x12345678; private static final long ENCRYPTION_KEY_2 = 0x23456789; private static final long ENCRYPTION_KEY_3 = 0x34567890; private InputStream baseInputStream = null; private final PKZIPCRC32 checksumEngine = new PKZIPCRC32(); private long[] keys = null; public ZipCryptoInputStream(ZipArchiveEntry zipEntry, InputStream inputStream, String passwd) throws Exception { baseInputStream = inputStream; // Decryption // ---------- // PKZIP encrypts the compressed data stream. Encrypted files must // be decrypted before they can be extracted. // // Each encrypted file has an extra 12 bytes stored at the start of // the data area defining the encryption header for that file. The // encryption header is originally set to random values, and then // itself encrypted, using three, 32-bit keys. The key values are // initialized using the supplied encryption password. After each byte // is encrypted, the keys are then updated using pseudo-random number // generation techniques in combination with the same CRC-32 algorithm // used in PKZIP and described elsewhere in this document. // // The following is the basic steps required to decrypt a file: // // 1) Initialize the three 32-bit keys with the password. // 2) Read and decrypt the 12-byte encryption header, further // initializing the encryption keys. // 3) Read and decrypt the compressed data stream using the // encryption keys. // Step 1 - Initializing the encryption keys // ----------------------------------------- // // Key(0) <- 305419896 // Key(1) <- 591751049 // Key(2) <- 878082192 // // loop for i <- 0 to length(password)-1 // update_keys(password(i)) // end loop // // Where update_keys() is defined as: // // update_keys(char): // Key(0) <- crc32(key(0),char) // Key(1) <- Key(1) + (Key(0) & 000000ffH) // Key(1) <- Key(1) * 134775813 + 1 // Key(2) <- crc32(key(2),key(1) >> 24) // end update_keys // // Where crc32(old_crc,char) is a routine that given a CRC value and a // character, returns an updated CRC value after applying the CRC-32 // algorithm described elsewhere in this document. keys = new long[] { ENCRYPTION_KEY_1, ENCRYPTION_KEY_2, ENCRYPTION_KEY_3 }; for (int i = 0; i < passwd.length(); ++i) { update_keys((byte) passwd.charAt(i)); } // Step 2 - Decrypting the encryption header // ----------------------------------------- // // The purpose of this step is to further initialize the encryption // keys, based on random data, to render a plaintext attack on the // data ineffective. // // Read the 12-byte encryption header into Buffer, in locations // Buffer(0) thru Buffer(11). // // loop for i <- 0 to 11 // C <- buffer(i) ^ decrypt_byte() // update_keys(C) // buffer(i) <- C // end loop // // Where decrypt_byte() is defined as: // // unsigned char decrypt_byte() // local unsigned short temp // temp <- Key(2) | 2 // decrypt_byte <- (temp * (temp ^ 1)) >> 8 // end decrypt_byte // // After the header is decrypted, the last 1 or 2 bytes in Buffer // should be the high-order word/byte of the CRC for the file being // decrypted, stored in Intel low-byte/high-byte order. Versions of // PKZIP prior to 2.0 used a 2 byte CRC check; a 1 byte CRC check is // used on versions after 2.0. This can be used to test if the password // supplied is correct or not. byte[] encryptionHeader = new byte[12]; baseInputStream.read(encryptionHeader); for (int i = 0; i < encryptionHeader.length; i++) { encryptionHeader[i] ^= decrypt_byte(); update_keys(encryptionHeader[i]); } } protected byte decrypt_byte() { byte temp = (byte) (keys[2] | 2); return (byte) ((temp * (temp ^ 1)) >> 8); } @Override public int read() throws IOException { // // Step 3 - Decrypting the compressed data stream // ---------------------------------------------- // // The compressed data stream can be decrypted as follows: // // loop until done // read a character into C // Temp <- C ^ decrypt_byte() // update_keys(temp) // output Temp // end loop int read = baseInputStream.read(); read ^= decrypt_byte(); update_keys((byte) read); return read; } private final void update_keys(byte ch) { keys[0] = checksumEngine.crc32((int) keys[0], ch); keys[1] = keys[1] + (byte) keys[0]; keys[1] = keys[1] * 134775813 + 1; keys[2] = checksumEngine.crc32((int) keys[2], (byte) (keys[1] >> 24)); } }

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  • Is there anyone with an Thinkpad Edge E320 with working Fn-Keys?

    - by Wauzl
    I recently bought a new Lenovo ThinkPad Edge E320. I'm having trouble with my Fn-Keys. The ones for Sound, Brightness and MUltimedia work but those that toggle Wifi/Bluetooth, Webcam and Microphone on and off won't. Fortunately the Wifi, Webcam and Mic are enabled by default. My problem is that I can't disable them (which would be nice to know that this works) and that I can't enable Bluetooth. (I checked that my machine has bluetooth support) Can't say if it would work in Windows as I purchased a machine without Windows. Here is my dmesg: http://pastebin.com/gAgYeDG7 Thanks for reading :)

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  • Safest way (i.e. HTTPS, POST, PGP) to send decryption keys through the web?

    - by theGreenCabbage
    I am in the final stages of development for my Revit plugin. This plugin is programmed in C#, and distributed via a DLL. One of the DLLs is an encrypted SQLite database (with proprietary data) that is in the form of a DLL. Currently, in development stages, the decryption key for the SQLite database is hardcoded in my main DLL (the program's DLL). For distribution, since DLLs are easily decompilable, I am in need of a new method to decrypt the DLL. My solution is to send our decryption keys from our servers securely to the host's computer. I was looking in POST, thinking it was more secure than GET, but upon research, it appears it's similarly insecure, only more "obscure" than GET. I also looked into HTTPS, but Hostgator requires extra money for HTTPS use. I am in need of some advice - are there any custom solutions I can do to implement this?

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  • Why do control keys (ctrl, shift, alt) not work sometimes?

    - by EricSchaefer
    Sometimes (about once a week) the control keys (ctrl, shift, alt) so not work anymore. They do work when I boot up, but after a while they stop working. Logging out and in again repairs it. What can cause something like that? Edit: It just happened again. Incidentally it happened right after vmware-player crashed just as the last time. Coincidence? Edit: It is a laptop keyboard (HP EliteBook 8730w) with german layout.

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  • 2-column table with two foreign keys. Performance/design question.

    - by Emanuel
    Hello everyone! I recently ran into a quite complex problem and after looking around a lot I couldn't find a solution to it. I've found answers to my questions many times before on stackoverflow.com, so I decided to post here. So I'm making a user/group managment system for a web-based project, and I'm storing all related data into a postgreSQL database. This system relies on three tables: USERS GROUPS GROUP_USERS The two first tables simply define all the users and all the groups on the site, and the last table, GROUP_USERS, stores the groups every user is part of. It only has two columns: USER_ID GROUP_ID Since every user can be a member of several groups, I decided to make a separate table for this purpose, rather than storing a comma separated column in the USERS-table. Now, both columns are foreign keys, and I want to make them both primary keys as well, this since each combination of USER_ID and GROUP_ID has to be unique, and if I give them the constraint UNIQUE pgAdmin tells me that each table should have at least one Primary key. But now I am stuck with what seems to be a lot of indexes and relations to a very small table only containing numbers. In the end, I want this table to be as fast as possible, even if containing tens of thousands of rows. Size on disk shouldn't be a problem since its just all numbers anyway, but it feels quite stupid to have a full-sized index refering to a smaller table. Should I stick with my current solution, store comma-separated values in a column in the USERS-table or is there any other solution I should be aware of. PS. I don't want to use an array-column, even if they are supported by postgreSQL. I want to be as generic as possible so I can switch database later on, if necessary. EDIT: I other words, will using a compound primary key and two foreign keys in one table with only two columns have a negative impact on performance rather than the opposite due to the size of the generated index? Thank you!

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  • Why can`t we treat SSL Certs like Pgp keys instead of trusting CAs?

    - by yarun can
    I am dumb and stupid and I do not know all the technical aspects of SSL and server/client side implications and implementations. However I understand them good enough from user point of view to use SSL and encyrption daily. I was thinking that how silly it is to trust some unknown/known CAs when it comes to our our certificates for our servers. There had been many cases of misconduct, misuse, compromises and theft of certificates/ca keys from those places. On top of those known issues we also have to pay these guys regularly. I am wondering why can not we use/treat web server certificates like we use our pgp keys? So I sign a SSL certificate and send to a central server. And then each user accessing my site checks the validity and the keys from some central server (like pgp key servers). Is this a stupid idea? If so what could be a better idea than current system of issuing valid certificates. I am looking for a better than more secure idea. Naturally this is not a solution to an existing problem, rather it will be a hypothetical solution for some future implementation of a currently messed up web of trust on the internet due to recent news about NSA and their criminal buddies around the world. thanks

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  • How to remap Fn key combinations (Lenovo G500)

    - by Anatoli
    I am running Kubuntu 13.10 on a Lenovo G500 laptop. My question is similar to this one: How can I remap my F keys on my HP laptop? That is to say, my F1-F12 keys are mapped to certain special functions, and only holding down the Fn key restores access to the standard F1-F12 keys. How do I remap certain keys? I would like to know if there is a way to remap Fx to Fn+Fx and vice-versa. As per the instructions of #87043 I checked my BIOS and there is no option to switch the Fx/Fn key functionality. Googling through Leonovo's support forums indicates a BIOS update enabling this is in the works, but there's no indication of when it will be complete. Using xev I was able to see what X sees when F1-F12 are pressed. Some send separate keycodes, but some are somehow mapped to key combinations or other unknown things: F1 - XF86AudioMute F2 - XF86AudioVolumeLower F3 - XF86AudioVolumeRaise F4 - Alt_L + F4 F5 - F5 F6 - Disables touchapd, cannot quite understand what xev tells me is happening, reenables if disabled (Kernel log reveals these have well-defined scancodes not assigned to any keycodes) F7 - XF86WLAN F8 - Alt_L + Ctrl_L + Tab F9 - Turns off LCD backlight, xev sees nothing F10 - Super_L + p F11 - XF86MonBrightnessLower F12 - XF86MonBrightnessRaise Following the instrusctions on this page: How do I remap certain keys? I remapped all the keys that have definite keycodes (F1, F2, F3, F5, F7, F11, F12) This still leaves the F4, F6, F8, F9, F10 keys not functioning properly. This is especially frustarting since F4, F6, F9 now kill the current window, the touchpad and screen, respectively. Any help on remapping these keys to their proper functions would be much appreciated! -Anatoli xev output for these 5 keys: F4 KeyPress event, serial 40, synthetic NO, window 0x4800001, root 0x9d, subw 0x0, time 3674037, (228,298), root:(911,321), state 0x0, keycode 64 (keysym 0xffe9, Alt_L), same_screen YES, XLookupString gives 0 bytes: XmbLookupString gives 0 bytes: XFilterEvent returns: False FocusOut event, serial 40, synthetic NO, window 0x4800001, mode NotifyGrab, detail NotifyAncestor FocusIn event, serial 40, synthetic NO, window 0x4800001, mode NotifyUngrab, detail NotifyAncestor KeymapNotify event, serial 40, synthetic NO, window 0x0, keys: 4294967197 0 0 0 0 0 0 0 65 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 KeyRelease event, serial 40, synthetic NO, window 0x4800001, root 0x9d, subw 0x0, time 3674040, (228,298), root:(911,321), state 0x8, keycode 70 (keysym 0xffc1, F4), same_screen YES, XLookupString gives 0 bytes: XFilterEvent returns: False KeyRelease event, serial 40, synthetic NO, window 0x4800001, root 0x9d, subw 0x0, time 3674042, (228,298), root:(911,321), state 0x8, keycode 64 (keysym 0xffe9, Alt_L), same_screen YES, XLookupString gives 0 bytes: XFilterEvent returns: False ClientMessage event, serial 40, synthetic YES, window 0x4800001, message_type 0x12a (WM_PROTOCOLS), format 32, message 0x12b (WM_DELETE_WINDOW) F6 disabling touchpad MappingNotify event, serial 40, synthetic NO, window 0x0, request MappingKeyboard, first_keycode 8, count 248 FocusOut event, serial 40, synthetic NO, window 0x4600001, mode NotifyGrab, detail NotifyAncestor FocusIn event, serial 40, synthetic NO, window 0x4600001, mode NotifyUngrab, detail NotifyAncestor KeymapNotify event, serial 40, synthetic NO, window 0x0, keys: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 MappingNotify event, serial 41, synthetic NO, window 0x0, request MappingKeyboard, first_keycode 8, count 248 F6 enabling touchpad MappingNotify event, serial 42, synthetic NO, window 0x0, request MappingKeyboard, first_keycode 8, count 248 FocusOut event, serial 42, synthetic NO, window 0x4600001, mode NotifyGrab, detail NotifyAncestor FocusIn event, serial 42, synthetic NO, window 0x4600001, mode NotifyUngrab, detail NotifyAncestor KeymapNotify event, serial 42, synthetic NO, window 0x0, keys: 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 MappingNotify event, serial 43, synthetic NO, window 0x0, request MappingPointer, first_keycode 0, count 0 F8 doing whatever it is F8 does KeyPress event, serial 40, synthetic NO, window 0x4600001, root 0x9d, subw 0x0, time 3508985, (13,-12), root:(696,11), state 0x0, keycode 64 (keysym 0xffe9, Alt_L), same_screen YES, XLookupString gives 0 bytes: XmbLookupString gives 0 bytes: XFilterEvent returns: False KeyPress event, serial 40, synthetic NO, window 0x4600001, root 0x9d, subw 0x0, time 3508986, (13,-12), root:(696,11), state 0x8, keycode 37 (keysym 0xffe3, Control_L), same_screen YES, XLookupString gives 0 bytes: XmbLookupString gives 0 bytes: XFilterEvent returns: False KeyPress event, serial 40, synthetic NO, window 0x4600001, root 0x9d, subw 0x0, time 3508988, (13,-12), root:(696,11), state 0xc, keycode 23 (keysym 0xff09, Tab), same_screen YES, XLookupString gives 1 bytes: (09) " " XmbLookupString gives 1 bytes: (09) " " XFilterEvent returns: False KeyRelease event, serial 40, synthetic NO, window 0x4600001, root 0x9d, subw 0x0, time 3508989, (13,-12), root:(696,11), state 0xc, keycode 64 (keysym 0xffe9, Alt_L), same_screen YES, XLookupString gives 0 bytes: XFilterEvent returns: False KeyRelease event, serial 40, synthetic NO, window 0x4600001, root 0x9d, subw 0x0, time 3508991, (13,-12), root:(696,11), state 0x4, keycode 37 (keysym 0xffe3, Control_L), same_screen YES, XLookupString gives 0 bytes: XFilterEvent returns: False KeyRelease event, serial 40, synthetic NO, window 0x4600001, root 0x9d, subw 0x0, time 3508994, (13,-12), root:(696,11), state 0x0, keycode 23 (keysym 0xff09, Tab), same_screen YES, XLookupString gives 1 bytes: (09) " " XFilterEvent returns: False F9 gives no output to xev F10 doing whatever it is F10 does KeyRelease event, serial 40, synthetic NO, window 0x4600001, root 0x9d, subw 0x0, time 3586076, (9,-14), root:(692,9), state 0x0, keycode 10 (keysym 0x31, 1), same_screen YES, XLookupString gives 1 bytes: (31) "1" XFilterEvent returns: False KeyPress event, serial 40, synthetic NO, window 0x4600001, root 0x9d, subw 0x0, time 3586552, (9,-14), root:(692,9), state 0x0, keycode 133 (keysym 0xffeb, Super_L), same_screen YES, XLookupString gives 0 bytes: XmbLookupString gives 0 bytes: XFilterEvent returns: False KeyPress event, serial 40, synthetic NO, window 0x4600001, root 0x9d, subw 0x0, time 3586554, (9,-14), root:(692,9), state 0x40, keycode 33 (keysym 0x70, p), same_screen YES, XLookupString gives 1 bytes: (70) "p" XmbLookupString gives 1 bytes: (70) "p" XFilterEvent returns: False KeyRelease event, serial 40, synthetic NO, window 0x4600001, root 0x9d, subw 0x0, time 3586557, (9,-14), root:(692,9), state 0x40, keycode 33 (keysym 0x70, p), same_screen YES, XLookupString gives 1 bytes: (70) "p" XFilterEvent returns: False KeyRelease event, serial 40, synthetic NO, window 0x4600001, root 0x9d, subw 0x0, time 3586560, (9,-14), root:(692,9), state 0x40, keycode 133 (keysym 0xffeb, Super_L), same_screen YES, XLookupString gives 0 bytes: XFilterEvent returns: False

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  • Simple way to use Foreign Key values for sorting?

    - by Brian Rizzo
    Disclaimer: I jumped to C# 2008 recently and SubSonic 3 (3.0.0.4) at the same time. I haven't used Linq for much of anything in the past. Is there an easy way to use the foreign key display value for sorting, rather than the FK Id (which is numeric)? I've added a new Find method in my ActiveRecord.tt to help with sorting based on a string field name but after doing some testing I realized that even though its working as it should be, I am not handling foreign key fields at all (they are just sorting by their value). Even if I need to change how I am accessing the data it is early enough in the project to do that. Just looking for suggestions.

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  • Linq to Entities, checking for specific foreign key id?

    - by AaronLS
    I am trying to get rows where the foreign key ParentID == 0, and this is what I am trying but I get a NotSupportedException because it can't translate the ArrayIndex [0]: IQueryable<ApplicationSectionNode> topLevelNodeQuery = from n in uacEntitiesContext.ApplicationSectionNodeSet where (int)n.Parent.EntityKey.EntityKeyValues[0].Value == 0 orderby n.Sequence select n; So I need to pull that ArrayIndex out of the query so that the runtime can successfully translate the query. I'm not sure how to do that though. How does one query a specific object via it's primary key or set of objects via foreign key? Edit: Note that there is not actually a row in the table with NodeId == 0, the 0 is a magic value(not my idea) to indicate top level nodes. So I can't do n.Parent.NodeId == 0

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  • DbMetal chokes on repeated foreign key references in SQLite - any ideas?

    - by DanM
    I've been struggling to get DbMetal to process my SQLite database. I finally isolated the problem. It won't allow a table to have two foreign key references to the same column. For example, a SQLite database with these two tables will fail: CREATE TABLE Person ( Id INTEGER PRIMARY KEY, Name TEXT NOT NULL ); CREATE TABLE Match ( Id INTEGER PRIMARY KEY, WinnerPersonId INTEGER NOT NULL REFERENCES Person(Id), LoserPersonId INTEGER NOT NULL REFERENCES Person(Id) ); I get this error: DbMetal: Sequence contains more than one matching element If I get rid of the second foreign key reference, no error occurs. So, this works: CREATE TABLE Match ( Id INTEGER PRIMARY KEY, WinnerPersonId INTEGER NOT NULL REFERENCES Person(Id), LoserPersonId INTEGER NOT NULL ); But I really need both "person" columns to reference the person table. I submitted a bug report for this, but I could use a workaround in the meantime. Any ideas?

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  • sqlalchemy: what is the difference between declaring the cascade within the foreign key vs relation?

    - by steve
    what is the difference between declaring the cascade within a foreign key vs relations? class Contact(Base): __tablename__ = 'contacts' id = Column(Integer, primary_key=True) addresses = relation("Address", backref="contact") class Address(Base): __tablename__ = 'addresses' id = Column(Integer, primary_key=True) contact_id = Column(Integer, ForeignKey('contact.id', onupdate="CASCADE", ondelete="CASCADE"))) vs class Contact(Base): __tablename__ = 'contacts' id = Column(Integer, primary_key=True) addresses = relation("Address", backref="contact", cascade="all, delete-orphan") class Address(Base): __tablename__ = 'addresses' id = Column(Integer, primary_key=True) contact_id = Column(Integer, ForeignKey('contact.id')) with the foreign key declaration, it seems like the cascade is enforced at the database level. how does the relations approach work? thanks!

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  • Does Python Django support custom SQL and denormalized databases with no Foreign Key relationships?

    - by Jay
    I've just started learning Python Django and have a lot of experience building high traffic websites using PHP and MySQL. What worries me so far is Python's overly optimistic approach that you will never need to write custom SQL and that it automatically creates all these Foreign Key relationships in your database. The one thing I've learned in the last few years of building Chess.com is that its impossible to NOT write custom SQL when you're dealing with something like MySQL that frequently needs to be told what indexes it should use (or avoid), and that Foreign Keys are a death sentence. Percona's strongest recommendation was for us to remove all FKs for optimal performance. Is there a way in Django to do this in the models file? create relationships without creating actual DB FKs? Or is there a way to start at the database level, design/create my database, and then have Django reverse engineer the models file?

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