I would like to create fully dynamic where clause in Room.
Is there any way to make something like code below to work and return number of updated columns?
#Query("UPDATE table SET column = ${xyConstVal} WHERE :where")
fun updateTable(where:String):Int
Thanks.
I would like to create fully dynamic where clause in Room.
Instead of using #Query annotation in dao you could try using #RawQuery which accepts SupportSQLiteQuery as value then write your query in old fashioned way
Is there any way to make something like code below to work and return
number of updated columns?
A method, annotated with #Insert can return a long. This is the newly generated ID for the inserted row. A method, annotated with #Update can return an int. This is the number of updated rows.
In your case you can combine both
Related
I know that I can do that by using data class but I want to achieve Like this
// This is My Query
#Query("SELECT loan_amount,adv_interest_amount FROM new_pledge_receive WHERE (new_pledge_receive.bill_date BETWEEN :fromDate AND :toDate)")
fun getPledgeReceiveAmount(fromDate: Long,toDate: Long):LiveData<List<Pair<Double,Double>>> ```
Pair class has 2 properties: first and second. Try to set the name of the selected columns to fit these names.
Something like: SELECT my_custom_field as first, my_another_field as second FROM...
As they mention on the official website
For SELECT queries, Room will infer the result contents from the method's return type and generate the code that will automatically convert the query result into the method's return type. For single result queries, the return type can be any java object. For queries that return multiple values, you can use List or Array. In addition to these, any query may return Cursor or any query result can be wrapped in a LiveData.
I am working on Room database and trying to insert list of items(eg. list of Quotes which contains author name and a quote in my case).
Following is the code I am using:
// view model
BaseApp.daoInstance?.appDao()?.insertQuotes(response!!)
// dao
#Insert(onConflict = OnConflictStrategy.REPLACE)
fun insertQuotes(listData: MutableList<Quote>)
When I try to insert the same data again, it always inserts as a new data instead of replacing with the current items.
I have researched a lot for this OnConflictStrategy.REPLACE but could not find any proper answer.
Is there anyone facing the same issue and found solution or am I doing anything wrong?
Thank you in advance...!!!
Room, will not check and compare if you have the quote already in the DB.
What it will do is look if the primary key already exists in the DB if it does, Room will replace all old data with the new one.
In your case, you are not specifying an ID so the DB is generating a unique one for you.
What you should do is create a Query that will search for this quote in the DB something like this:
#Query("SELECT * from quote_table WHERE author = :author AND quote = :quote")
List<Quote> getQuoteByAuthorAndQuote(string author, string quote);
This should return a list with a single quote if one is found and empty if it does not exist.
If you would like to override the old one just update the data in the Quote POJO and insert it to the DB using Room.
Have you tried to index your main column and mark it as unique?
#Index(value = {"quote"}, unique = true)}
It suppose to search for your unique or primary key and compare then replace, while in your case you're not defining an ID so it will generate a unique one for you, so it won't even compare and will consider any item as a new one.
Write a new query and function to solve this issue.
When I had same problem, changes in imports did the trick, added following import:
import androidx.room.*;
Is there any way I can create and drop tables similar to a 'RawQuery'?
I tried with a #RawQuery annotation (which it would be the perfect solution for me) but when I am compiling I get an error saying methods annotated with RawQuery can't return void.
I read only SELECT, UPDATE and DELETE statements are allowed when using #Query.
I would like to achieve the "creation or deletion of tables" by passing a tablename as a parameter, something like the following:
#Query("DROP TABLE :name")
void deleteTable (String name);
Any ideas on how to achieve this?
Thanks!
Official doc states that,
RawQuery serves as an escape hatch where you can build your own SQL query at runtime but still use Room to convert it into
objects.
RawQuery methods must return a non-void type. If you want to execute a raw query that does not return any value, use
RoomDatabase#query methods.
or use it like,
#RawQuery
int deleteTable (SupportSQLiteQuery query); //We can return int status like it used to return with database.delete()
//Usage
dao.deleteTable(
new SimpleSQLiteQuery("DROP TABLE tablename")
)
The ting is, wit Room, you don't have to "drop" tables, the tables re created based on your entity classes (annotated with #Entity).
As far as I know, you usually need to drop tables in case the columns change or there are some updates on the "structure", with Room there's no point in doing this unless you change the structure of your entity that can't be automatically handled by the migration. In this case, Room gives you the chance to do the migration by yourself. Check the documentation here: https://developer.android.com/training/data-storage/room/migrating-db-versions
But like the documentation states, be really careful with this.
Is it possible to use SQLite's IN condition with Room?
I'm trying to select a list of items from my database where the value of a certain column (in this case a TEXT column) matches any one of a set of filter values. That's pretty easily done in SQL and SQLite, by my knowledge, just by adding an IN condition to your SELECT statement (see here). However, I can't seem to make it work with Room.
I keep getting this error:
Error:(70, 25) error: no viable alternative at input 'SELECT * FROM Table WHERE column IN :filterValues'
(where the input to the DAO #Query-annotated method is called filterValues)
I have tried three different methods now:
Passing the argument as a List<String>
Passing the argument as a String[]
And lastly passing the argument as simply a String, but formatted as (value_1, value_2, ..., value_n)
The last one in particular should work easily, as it will (or at least, it should) directly translate to SELECT * FROM Table WHERE column IN (value_1, value_2, ..., value_n), which is the exact way you would manually write out the SELECT if you were just accessing the database directly.
So as I was preparing to submit this, I double-checked a bunch of the stuff I had looked up previously and found the thing I had somehow missed and would have saved this question from being necessary.
As it turns out, both of these options:
Passing the argument as a List<String>
Passing the argument as a String[]
are viable (and you can replace String with any type the database can represent, such as char or int), you simply need to change the syntax in the #Query annotation from this:
#Query("SELECT * FROM Table WHERE column IN :filterValues")
to this:
#Query("SELECT * FROM Table WHERE column IN (:filterValues)")
Easy as pie, right?
Note that the third method above (passing the argument as simply a String, but formatted as (value_1, value_2, ..., value_n)) does not appear to be supported by Room, but that's probably not a bad thing, since that's the hard way.
Since I already had the whole thing typed out, I figured I would leave the question up in case other people are have as much difficulty finding this solution as I did and stumble upon this question.
Hi you can use this query:
#Query("SELECT * FROM user WHERE uid IN(:userIds)")
public abstract List findByIds(int[] userIds);
or
#Query("SELECT * FROM user WHERE uid IN(:userIds)")
public abstract List findByIds(List<Integer> userIds);
Similarly to above answers in Kotlin you can use vararg instead of array or list:
#Query("SELECT * FROM user WHERE uid IN (:userIds)")
fun getUsers(vararg userIds: Int): List<User>?
and use it like repository.getUsers(1, 2, 3).
If needed, to convert vararg to list see https://proandroiddev.com/kotlins-vararg-and-spread-operator-4200c07d65e1 (use *: format(output, *params)).
I am currently using greenDAO as the ORM for my Android Application. I ran into an issue when trying to execute a GROUPBY clause.
greenDAO does not have API / helper methods for performing groupby clauses, so I decided to use query() or queryRaw() methods available for the AbstractDAO class, where I can pass a valid SQL query. BUT, both these methods return a java.util.List, so what confuses me is that how can I get values of column aliases in the result?
Eg,
SELECT COUNT(ID) AS NUMOFRECORDS, NAME FROM PERSONS GROUP BY AGE
My entity will have NAME and AGE fields, but I created a column alias NUMOFRECORDS, which is not part of the Entity.
Appreciate your help!
This is a alternative solution for your question:
Include the ORDER BY insize of Where.
Ex:
List<Taxi> list = daoSession.getDaoTaxi().queryBuilder().where(new WhereCondition.StringCondition("1 GROUP BY cant_aciento")).list();
I'm stuck with a similar problem. It seems that greenDao doesn't support GROUP BY querys and it won't change in the future, according to what they said here:
GROUP BY is SQL-ish, so stick to SQL. greenDAO is about entities, where GROUP BY is unsupported.