CODEWITHSUNDEEP
c#sqlitewindows-8
Rahul Saksule
Rahul Saksule

Reputation: 417

during update query it throws NotSupportedException?

I am dealing with SQLite in windows store application.I am updating the values in table using

var tagPage = db.QueryAsync<MyModel>("UPDATE MyModel SET Tag =2 WHERE id = 1");
db.UpdateAsync(tagPage);

It throws an NotSupportedException on SQLite.cs class over the method 

public int Update(object obj, Type objType)
{
    if (obj == null || objType == null)
        {
            return 0;
        }

        var map = GetMapping(objType);

        var pk = map.PK;

        if (pk == null)
        {
            throw new NotSupportedException("Cannot update " + map.TableName + ": it has no PK");
        }

        var cols = from p in map.Columns
                   where p != pk
                   select p;
        var vals = from c in cols
                   select c.GetValue(obj);
        var ps = new List<object>(vals);
        ps.Add(pk.GetValue(obj));
        var q = string.Format("update \"{0}\" set {1} where {2} = ? ", map.TableName, string.Join(",", (from c in cols
                                                                                                        select "\"" + c.Name + "\" = ? ").ToArray()), pk.Name);
        return Execute(q, ps.ToArray());
}

because I think it wont get the primery key, where I have provided primery key in table. I tried it with async and await but no use, why it is happening? please help me

Upvotes: 2

Views: 1017

Answers (1)

chue x
chue x

Reputation: 18823

Regarding your NotSupportedException issue - I suspect that your model is missing the PrimaryKey attribute:

public class MyModel
{
    [PrimaryKey, AutoIncrement]
    public int Id { get; set; }

    public int Tag { get; set; }        
    public string Foo { get; set; }
}

You will need the attribute(s) above, even if your db schema already has them defined. At this time, Sqlite-Net does not read schema data from the db.

Some other thoughts:

Firstly, you should use only either the synchronous Sqlite-Net API, or the async API. Don't use both.

I personally prefer the synchronous API, as it appears to be more up to date. The async API has not been updated in 11 months, whereas the synchronous API was updated 4 months ago. Besides this I never was able to figure out how to do transactions using the async API. Again, this is personal preference.

Secondly, the Query and QueryAsync methods should be used only for querying (for SELECTs). They should not be used for UPDATEs. For adding/changing data, you will want to use these synchronous methods: Execute, Update, Insert, etc. If using the async API, there are the async counterparts (ExecuteAsync, etc).

Please read the Sqlite-Net Project page, as you will find a lot of helpful information there regarding general API usage.

Upvotes: 5

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