Converting List<int> to List<object> for One to Many relation with sqlite-net-extensions

Exoskeletor

which blob? i don't use blobs any more, you mean to create a blod in order to hash it? can you give me a table structure cause im getting confused, this is my structure now

[Table("Templates")]
public class Template
{
[PrimaryKey, AutoIncrement]
public int Id { get; set; }
public int Category { get; set; }
//[TextBlob("imagesBlobbed")]
[OneToMany, Indexed(Name = "TemplateImagesUnique", Unique = true)]
public List TemplateImages { get; set; }
public string ImagesHash { get; set; }
//public string imagesBlobbed { get; set; }
}
[Table("TemplateImages")]
public class TemplateImage
{
[PrimaryKey, AutoIncrement]
public int Id { get; set; }
public int Category { get; set; }
public int Image { get; set; }
[ForeignKey(typeof(Template))]
public int TemplateId { get; set; }
}

Lost User

Exoskeletor wrote:

which blob? i don't use blobs any more

With the blob I meant the image you're storing.

\[Table("TemplateImages")\]
public class TemplateImage
{
    \[PrimaryKey, AutoIncrement\]
    public int Id { get; set; }
    public int Category { get; set; }
    public stream Image { get; set; } // why was that an int? Numbers aren't images
    public string ImageHash { get; set; }
    \[ForeignKey(typeof(Template))\]
    public int TemplateId { get; set; }
}

Bastard Programmer from Hell :suss: If you can't read my code, try converting it here[^] "If you just follow the bacon Eddy, wherever it leads you, then you won't have to think about politics." -- Some Bell.

Exoskeletor

oh im storing the images as int cause this int represent the ResourceId of the image, i thought that since the images are stored inside the local app folder that is more efficient to store the

ResourceId

rather than the image itself (which is a string, my images are vectors .xml files) Is this a bad idea? Im starting thinking that this is a very silly idea :) because i guess the Resource id is generated every time i compile a new version of my app, so im trying to create a unique hash of something that is not unique

Exoskeletor

What if i do this: 1) Get the xml content as string 2) convert them with +s from all the images to one string, 3) md5hash this string? It sounds like an overkill although, i think i have to read the images as files, and in order to do that i have to open a stream, this sounds very heavy to me, cause i also have to move the images to assets, android can't read images from drawable folder. I think im coming to a dead end and the only solution is to delete and recreate the database every time the app is opened, or every time i made a new update of the app, im not sure

Lost User

Exoskeletor wrote:

Im starting thinking that this is a very silly idea :) because i guess the Resource id is generated every time i compile a new version of my app, so im trying to create a unique hash of something that is not unique

You don't want to hash it's id, but the data that represents the image :) You want to compare those to each other, not the Id's that identify the image.

Bastard Programmer from Hell :suss: If you can't read my code, try converting it here[^] "If you just follow the bacon Eddy, wherever it leads you, then you won't have to think about politics." -- Some Bell.

Lost User

Exoskeletor wrote:

convert them with +s from all the images to one string,

Not "all" the images; you need a separate fingerprint for each image.

Exoskeletor wrote:

i think i have to read the images as files, and in order to do that i have to open a stream, this sounds very heavy to me

You'd have to read the images anyway to use them; opening them as a stream is not heavy, but the most used way to handle binary data. Since it is XML-data and not binary, you may get away with simply reading that string without needing a stream.

Bastard Programmer from Hell :suss: If you can't read my code, try converting it here[^] "If you just follow the bacon Eddy, wherever it leads you, then you won't have to think about politics." -- Some Bell.

Exoskeletor

but if i have a seperate hash for every image where im going to store it? in the templateimage table? one hash for each image?

Lost User

Exoskeletor wrote:

one hash for each image?

Yes; since each hash represents the content in the image, in another form. If you have that for each image, then looking if you already have it is as easy as getting the hash from the new image (the one you want to compare to the ones already there), and see if it is in there.

Bastard Programmer from Hell :suss: If you can't read my code, try converting it here[^] "If you just follow the bacon Eddy, wherever it leads you, then you won't have to think about politics." -- Some Bell.

Exoskeletor

yes but what if i don't mind if the same image exist but not in the same order? thats why im thinking of converting all bytes into one. A template might have some images that other template have (in the future). Since i am generating bitmaps for every image maybe is not so expensive to generate one more md5 from a bitmap that will do that

public static byte[] ConcatByteArrays(params byte[][] arrays)
{
return arrays.SelectMany(x => x).ToArray();
}

and then have a hash for every template AND a hash for every image

Exoskeletor

I tried with this code but im getting an out of memory exception

static class DatabaseHelper
{
public static string GetMD5Hash(string content)
{
using (var md5 = MD5.Create())
{
byte[] computedHash = md5.ComputeHash(Encoding.UTF8.GetBytes(content));
return new System.Runtime.Remoting.Metadata.W3cXsd2001.SoapHexBinary(computedHash).ToString();
}
}

    public static string GetMD5Hash(byte\[\] content)
    {
        using (var md5 = MD5.Create())
        {
            byte\[\] computedHash = md5.ComputeHash(Encoding.UTF8.GetBytes(BitConverter.ToString(content).Replace("-", "")));
            return new System.Runtime.Remoting.Metadata.W3cXsd2001.SoapHexBinary(computedHash).ToString();
        }
    }
    public static string DrawableToMD5(int drawableId)
    {
        var templateDB = new TemplateDB();
        return GetMD5Hash(templateDB.DrawableToByteArray(drawableId));
    }
    private static SQLiteConnection instance;
    public static SQLiteConnection db()
    {
        if (instance == null)
            instance = new SQLiteConnection(System.IO.Path.Combine(System.Environment.GetFolderPath(System.Environment.SpecialFolder.Personal), "TemplatesData.db"));

        return instance;
    }
    public static void CloseConnection()
    {
        if (instance != null)
        {
            instance.Close();
            instance.Dispose();
            instance = null;
        }
    }

}
public class TemplateDB
{
    public enum TemplateCategories
    {
        Emojis,
        Stars,
        Hearts,
        Characters,
        Emotions,
    }

    public static byte\[\] ConcatByteArrays(params byte\[\]\[\] arrays)
    {
        return arrays.SelectMany(x => x).ToArray();
    }

    public static byte\[\] ConcatByteList(List list)
    {
        return list
            .SelectMany(a => a)
            .ToArray();
    }

    public static Bitmap GetBitmapFromVectorDrawable(Context context, int drawableId)
    {
        Drawable drawable = ContextCompat.GetDrawable(context, drawableId);
        if (Build.VERSION.SdkInt < Android.OS.BuildVersionCodes.Lollipop)
        {
            drawable = (DrawableCompat.Wrap(drawable)).Mutate();

Exoskeletor

What if i just give my own unique hash in every template manually? i cant think of another solution, either way im creating a list of templates before inserting them to db, why not just give them my own hash?

Lost User

Exoskeletor wrote:

What if i just give my own unique hash in every template manually? i cant think of another solution, either way im creating a list of templates before inserting them to db, why not just give them my own hash?

You already assign them an id; if you want to compare if two complex objects are the same, you usually do that by comparing their hash values.

Bastard Programmer from Hell :suss: If you can't read my code, try converting it here[^] "If you just follow the bacon Eddy, wherever it leads you, then you won't have to think about politics." -- Some Bell.

Lost User

That's reading all the images and making one big array of bytes of it; may be a bit much for the memorymanager.

Bastard Programmer from Hell :suss: If you can't read my code, try converting it here[^] "If you just follow the bacon Eddy, wherever it leads you, then you won't have to think about politics." -- Some Bell.

Exoskeletor

well i cant seem to find a way to do that, i have also create this funny post in stackoverflow with that matter :) c# - Checking if data exist in sqlite-net before inserting them to database - Stack Overflow[^]

Lost User

Are you trying to compare bitmaps, or simply looking for a way to do an insert-query while checking if there's already such a record? In pseudo, comparing bitmaps would be similar to below;

Bitmap bitmap1 = (get bitmap from somewhere)
string hashedImage = MakeMD5(bitmap1);
Bitmap compareTo = (get bitmap you want to compare to)
string compareToHash = MakeMD5(compareTo);
bool imagesAreEqual = (hashedImage == compareToHash);

That's not helping though if you are trying an insert that does an update when the record is already there.

Bastard Programmer from Hell :suss: If you can't read my code, try converting it here[^] "If you just follow the bacon Eddy, wherever it leads you, then you won't have to think about politics." -- Some Bell.

Exoskeletor

I just want to insert a template in the database only if does not exist. By not exist i mean the List of images to not exist in another template. The only solution i can think of is a predefined hash value

Lost User

Exoskeletor wrote:

I just want to insert a template in the database only if does not exist.

:D You don't need a hash for that, sorry for pointing you in the wrong direction :rolleyes: Instead of an insert-command you usually use, you can use the "INSERT OR REPLACE" command; see SQLite REPLACE: Insert or Replace The Existing Row[^]

Bastard Programmer from Hell :suss: If you can't read my code, try converting it here[^] "If you just follow the bacon Eddy, wherever it leads you, then you won't have to think about politics." -- Some Bell.

Exoskeletor

but how can sqlite know to replace a record? both my tables have a primary unique key

[Table("Templates")]
public class Template
{
[PrimaryKey, AutoIncrement]
public int Id { get; set; }
public int Category { get; set; }
//[TextBlob("imagesBlobbed")]
[OneToMany, Unique]
public List TemplateImages { get; set; }
public string ImagesHash { get; set; }
//public string imagesBlobbed { get; set; }
}
[Table("TemplateImages")]
public class TemplateImage
{
[PrimaryKey, AutoIncrement]
public int Id { get; set; }
public int Category { get; set; }
public string ImagesHash { get; set; }
public int Image { get; set; }
[ForeignKey(typeof(Template))]
public int TemplateId { get; set; }
}

doesnt that make them unique. Also, this is replacing items according to the primary key it says? so if i have a template with id 5, and i delete it one day, the template that belong to id 6 wll go to the position of id 5? and so on?

Exoskeletor

also i tried in this code

public static void AddTemplate(int category, List images)
{
var templateDB = new TemplateDB();
var imageByteList = new List();

        foreach (int image in images)
        {
            //imageByteList.Add(templateDB.DrawableToByteArray(image));
        }
        var tmpl = new Template()
        {
            Category = category,
        };
        var img1 = new TemplateImage()
        {
            Category = category,
            Image = images\[0\],
            //ImagesHash = DatabaseHelper.GetMD5Hash(imageByteList\[0\]),
        };
        var img2 = new TemplateImage()
        {
            Category = category,
            Image = images\[1\],
            //ImagesHash = DatabaseHelper.GetMD5Hash(imageByteList\[1\]),
        };
        var img3 = new TemplateImage()
        {
            Category = category,
            Image = images\[2\],
            //ImagesHash = DatabaseHelper.GetMD5Hash(imageByteList\[2\]),
        };
        var img4 = new TemplateImage()
        {
            Category = category,
            Image = images\[3\],
            //ImagesHash = DatabaseHelper.GetMD5Hash(imageByteList\[3\]),
        };
        var img5 = new TemplateImage()
        {
            Category = category,
            Image = images\[4\],
            //ImagesHash = DatabaseHelper.GetMD5Hash(imageByteList\[4\]),
        };
        tmpl.TemplateImages = new List() { img1, img2, img3, img4, img5 };
        //tmpl.ImagesHash = DatabaseHelper.GetMD5Hash(ConcatByteList(imageByteList));
        var result = DatabaseHelper.db().Query("Select \* from Templates where ImagesHash=?", tmpl.ImagesHash);
        if (result.Count == 0)
        {
        DatabaseHelper.db().InsertAll(tmpl.TemplateImages);
        DatabaseHelper.db().Insert(tmpl);
        DatabaseHelper.db().UpdateWithChildren(tmpl);
        }

to replace insert with insertorupdate and my template database was empty. id was always 0 in every attemp to insert something to db, do you know why? here is the database structure

[Table("Templates")]
public class Template
{
[PrimaryKey, AutoIncrement]
public int Id { get; set; }
public int Category { get; set; }
//[TextBlob("imagesBlobbed")

Lost User

The page that I linked to lets you try the SQL statements online :) Hadn't seen that it is a real "replace", not an insert "or" update; but it explains that too. It does look like it honors the unique constraint, so should work with a primary key too.

Exoskeletor wrote:

so if i have a template with id 5, and i delete it one day, the template that belong to id 6 wll go to the position of id 5? and so on?

Id's that have been used already do not get re-used; so if you delete 5 and 6 exists, another insert would give you 7, not 5, even if that position is empty.

Bastard Programmer from Hell :suss: If you can't read my code, try converting it here[^] "If you just follow the bacon Eddy, wherever it leads you, then you won't have to think about politics." -- Some Bell.