I'm writing a web application where users can upload images. I wonder what's the best practice of assigning unique names to images ? I thought MD5 can ben useful and enough, but since each image has an owner, do I have to use MD5 ? I mean it could be enough to rename with Userid + imagename + creationdate ?
Your database gives you a unique ID for each record. Though there are many different ways to do what you want, it is usually best to use this ID as a prefix/suffix to the name of the image. So, for these records:
ID | name
15 image.png
23 image.png
you could display something like: 15_image.png, 23_image.png
No, it would not be enough as the user might want to upload several images with the same name.
The easiest solution is to use a sequence number with the image name. You can be certain that there is no other image with the same name and there will never be one. With a hash function there is always an ever so slight chance of collision.
Related
I'm looking over some UniData fields for distinct values but I'm hoping to find a simpler way of doing it. The values aren't keys to anything so right now I'm selecting the records I'm interested in and selecting the data I need with SAVING UNIQUE. The problem is, in order to see what I have all I know to do is save it out to a savedlist and then read through the savedlist file I created.
Is there a way to see the contents of a select without running it against a file?
If you are just wanted to visually look over the data, use LIST instead of SELECT.
The general syntax of the command is something like:
LIST filename WITH [criteria] [sort] [attributes | ALL]
So let's say you have a table called questions and want to look over all the author for questions that used the tag unidata. Your query might look something like:
LIST questions WITH tag = "unidata" BY author author
Note: The second author isn't a mistake, it's the start of the list of attributes you want displayed - in this case just author, but you might want the record id as well, so you could do #ID author instead. Or just do ALL to display everything in each record.
I did BY author here as it will make spotting uniques easier, but you can also use other query features like BREAK.ON to help here as well.
I don't know why I didn't think of it at the time but I basically needed something like SQL's DISTINCT statement since I just needed to view the unique values. Replicating DISTINCT in UniData is explained here, https://forum.precisonline.com/index.php?topic=318.0.
The trick is to sort on the values using BY, get a single unique value of each using BREAK-ON, and then suppress everything except those unique values using DET-SUP.
LIST BUILDINGS BY CITY BREAK-ON CITY DET-SUP
CITY.............
Albuquerque
Arlington
Ashland
Clinton
Franklin
Greenville
Madison
Milton
Springfield
Washington
I have 2 column in my table setting
with the following values
KEY VALUE
company ABC
phone 14344
address Somerset City
I need to display this like a single record or a flatten
array in the view/blade page
something like
{{$sett->company}}
{{$sett->phone}}
or an array with lookup
{{$myarray('company')}}
{{$myarray('phone')}}
The idea is if I add another settings like contact us email address
for my website I don't want to add another column.
I know this is achievable in controller by creating different variable
and executing different query but I'm kind of looking for some options here.
Thanks for the help really appreciated.
You can use $settings->pluck('value', 'key') to get your result. Read more here: https://laravel.com/docs/5.4/collections#method-pluck
I would like to get some information from the user profiles of a certain domain.
www.domain.com/profiles/[userID]
The main problem is that the user ID is like:
4fc34f1ad3d85a000300b5a4
4fc34f1ad3d85a000300b5a4
4f4bdd96848740000300026a
4f09884f9cc1590001019c98
4f1bcd5f33aa850001011811
4faa2801c619ad0003011c7e
4e4f506ac9d69600010010ca
so if I wnat the user profile of a certain user I have to put
www.domain.com/profiles/4fc34f1ad3d85a000300b5a4
www.domain.com/profiles/4f4bdd96848740000300026a
www.domain.com/profiles/4f09884f9cc1590001019c98
www.domain.com/profiles/4f1bcd5f33aa850001011811
www.domain.com/profiles/4faa2801c619ad0003011c7e
www.domain.com/profiles/4e4f506ac9d69600010010ca
What kind of ID is that? How I know the subjacent canonical order?
Other times was a lot easier because the user ID only was integers.
www.domain.com/profiles/1
www.domain.com/profiles/2
www.domain.com/profiles/3
www.domain.com/profiles/4
www.domain.com/profiles/5
I would like to know if this is some kind of encoding or what.
What kind of ID on the URL is that?
Thank you in advance.
Looks like an MD5 hash. So either it's a random hash, or it might a hash of the previously used ID, or something completely different. Either way apart from brute force guessing, there's no simple way to decode them.
http://en.wikipedia.org/wiki/MD5
These ID's use hexadecimal - notice there are no letters above 'f'.
The similarities between ID's are interesting - could you provide the ID's of some consecutively created pages, to check if there is a pattern to how the ID changes.
Or the website may just generate a random number between certain limits and convert to hex.
I am trying a case where we changed a field name in our entity. we have something like this for example
class Person {
String name; //The original declaration was "String fullName"
}
According to objectify you have to use annonation #AutoLoad(""). This is ok and it works as Google Datastore doesn't delete the data Actually but it makes a new field so this annotation is like a mapping between the old and the new field. No problem when you are reading the whole table.
The problem arises when you apply a filter on your query (Suppose you made 5 objects with old name and 5 with new name). The result of your query depends on whether you used the old variable name or the new one (returns back only 5 but never the 10). It won't fetch both of them and map them. Any Suggestions for this problem? I hope i explained it in a clear way.
Thanks in advance
The simplest straight forward solution. fetch all data with the annonation "AutoLoad()". Then store them again. In this way they will be saved as the new field. The old one doesn't exist anymore or at least it doesn't contain any data anymore. It is like migrating the data from the old name to the new name. Anyone has better suggestions ?
If you've changed the name of your field, you need to load and re-put all your data (using the mapreduce API would be one option here). There's no magic way around this - the data you've stored exists with two different names on disk.
You can use #OldName
http://www.mail-archive.com/google-appengine-java#googlegroups.com/msg05586.html
Consider an e-commerce application with multiple stores. Each store owner can edit the item catalog of his store.
My current database schema is as follows:
item_names: id | name | description | picture | common(BOOL)
items: id | item_name_id | picture | price | description | picture
item_synonyms: id | item_name_id | name | error(BOOL)
Notes: error indicates a wrong spelling (eg. "Ericson"). description and picture of the item_names table are "globals" that can optionally be overridden by "local" description and picture fields of the items table (in case the store owner wants to supply a different picture for an item). common helps separate unique item names ("Jimmy Joe's Cheese Pizza" from "Cheese Pizza")
I think the bright side of this schema is:
Optimized searching & Handling Synonyms: I can query the item_names & item_synonyms tables using name LIKE %QUERY% and obtain the list of item_name_ids that need to be joined with the items table. (Examples of synonyms: "Sony Ericsson", "Sony Ericson", "X10", "X 10")
Autocompletion: Again, a simple query to the item_names table. I can avoid the usage of DISTINCT and it minimizes number of variations ("Sony Ericsson Xperia™ X10", "Sony Ericsson - Xperia X10", "Xperia X10, Sony Ericsson")
The down side would be:
Overhead: When inserting an item, I query item_names to see if this name already exists. If not, I create a new entry. When deleting an item, I count the number of entries with the same name. If this is the only item with that name, I delete the entry from the item_names table (just to keep things clean; accounts for possible erroneous submissions). And updating is the combination of both.
Weird Item Names: Store owners sometimes use sentences like "Harry Potter 1, 2 Books + CDs + Magic Hat". There's something off about having so much overhead to accommodate cases like this. This would perhaps be the prime reason I'm tempted to go for a schema like this:
items: id | name | picture | price | description | picture
(... with item_names and item_synonyms as utility tables that I could query)
Is there a better schema you would suggested?
Should item names be normalized for autocomplete? Is this probably what Facebook does for "School", "City" entries?
Is the first schema or the second better/optimal for search?
Thanks in advance!
References: (1) Is normalizing a person's name going too far?, (2) Avoiding DISTINCT
EDIT: In the event of 2 items being entered with similar names, an Admin who sees this simply clicks "Make Synonym" which will convert one of the names into the synonym of the other. I don't require a way to automatically detect if an entered name is the synonym of the other. I'm hoping the autocomplete will take care of 95% of such cases. As the table set increases in size, the need to "Make Synonym" will decrease. Hope that clears the confusion.
UPDATE: To those who would like to know what I went ahead with... I've gone with the second schema but removed the item_names and item_synonyms tables in hopes that Solr will provide me with the ability to perform all the remaining tasks I need:
items: id | name | picture | price | description | picture
Thanks everyone for the help!
The requirements you state in your comment ("Optimized searching", "Handling Synonyms" and "Autocomplete") are not things that are generally associated with an RDBMS. It sounds like what you're trying to solve is a searching problem, not a data storage and normalization problem. You might want to start looking at some search architectures like Solr
Excerpted from the solr feature list:
Faceted Searching based on unique field values, explicit queries, or date ranges
Spelling suggestions for user queries
More Like This suggestions for given document
Auto-suggest functionality
Performance Optimizations
If there were more attributes exposed for mapping, I would suggest using a fast search index system. No need to set aliases up as the records are added, the attributes simply get indexed and each search issued returns matches with a relevance score. Take the top X% as valid matches and display those.
Creating and storing aliases seems like a brute-force, labor intensive approach that probably won't be able to adjust to the needs of your users.
Just an idea.
One thing that comes to my mind is sorting the characters in the name and synonym throwing away all white space. This is similar to the solution of finding all anagrams for a word. The end result is ability to quickly find similar entries. As you pointed out, all synonyms should converge into one single term, or name. The search is performed against synonyms using again sorted input string.