Go, Cassandra(cql) & UDT

[Baxter]

Hello @all,

i testing in the moment the cqlgo package and have a problem to insert data for a udt column.

Maybe, it´s here a person that have a solution, i hope...

I will insert following Data into the column: {name: "test1, available: 1}, {name: "test2, available: 2}, {name: "test3, available: 3}

for this a a create a struct and try this with following call:

type Rooms struct {

        name        string  `cql:"name"`

        available   int     `cql:"available"`

}

    

var rooms []Rooms

    

rooms = append(rooms, Rooms{name:"ground", available:grundflaeche})

rooms = append(rooms, Rooms{name:"coveredarea", available:uflaeche})

rooms = append(rooms, Rooms{name:"usablearea", available:nutzflaeche})

rooms = append(rooms, Rooms{name:"agricultural", available:lnutzflaeche})

rooms = append(rooms, Rooms{name:"livingspace", available:wohnflaeche})

if i call a insert statement in  become the error:

cannot marshal []main.Rooms into immodb.rooms{name=varchar,available=int}

 i had testing a lot, but nothing works;-(

Thanks

Baxter

[Ian Davis]

 

On Fri, May 22, 2015, at 01:02 PM, Baxter wrote:

cannot marshal []main.Rooms into immodb.rooms{name=varchar,available=int}

 

 i had testing a lot, but nothing works;-(

 

Have you tried making name and available exported fields on your Rooms type? Reflection based marshalling requires fields to be exported.

 

Ian

[Baxter]

Thank, for your reply..

 

I had this on cassandra side:

CREATE TYPE rooms (

    name text,

    available int

); 

CREATE TABLE test (

id uuid PRIMARY KEY,

rooms frozen<rooms>,

);

CREATE INDEX test_rooms_idx ON test (rooms);

[Konstantin Khomoutov]

On Fri, 22 May 2015 06:36:41 -0700 (PDT)
Baxter <baxte...@googlemail.com> wrote:

> Thank, for your reply..
[...]

Ian rather meant Go's rules for "exported" (visible in places other
than the current package) identifiers [1]. In other words, capitalize
the first letters of the names of the fields of your struct and see if
that works.

I would also advise you to start small and try reading [1] as a whole
and try working through a bunch of tutorials to understand the basic
rules of the language.

On a side note, if the essense of a reply wasn't clear to you, you
should have better stated it loud and clear -- there's nothing wrong
with admitting you didn't understand something.

1. https://golang.org/doc/effective_go.html#names

[Konstantin Khomoutov]

On Fri, 22 May 2015 06:36:41 -0700 (PDT)
Baxter <baxte...@googlemail.com> wrote:

> Thank, for your reply..
[...]

Consider also reading [1], especially the part about decoding -- it
explains basic rules most Go packages which make use of
reflection [2, 3] appy when deciding what data to serialize into which
struct fields, and back.

1. http://blog.golang.org/json-and-go
2. http://golang.org/pkg/reflect/
3. http://blog.golang.org/laws-of-reflection

[Baxter]

Ok, i had read a lot of stuff on the weekend but i´m only one step forward....

So, i can add one dataset into table but not more... For example, this works:

type RoomsItem struct {

    Room  string `cql:"room"`

    Available int `cql:"available"`

}

func main() {

  

    srv, err := newCqlSession()

    if err != nil {

        log.Fatal(err)

    }

    rooms := &RoomsItem{

        Room:  "main",

        Available: 1,

        

    }

    err = srv.Query("INSERT INTO objects(id, rooms) VALUES(?, ?)", gocql.TimeUUID(), rooms).Exec()

    if err != nil {

log.Fatal(err)

    }

}

With this example i had insert "{"room":"main", "Available": 1}" to the table, fine... so but i will add more than one;-) ( {"room":"main", "Available": 1},{"room":"bla", "Available": 5}....)

for this, i had change to this:

type RoomsItem struct {

    Room  string `cql:"room"`

    Available int `cql:"available"`

}

type Rooms struct {

    Items []RoomsItem

}

func main() {

  

    srv, err := newCqlSession()

    if err != nil {

        log.Fatal(err)

    }

    

    items := []RoomsItem{}

    rooms := Rooms{items}

    

    rooms.AddItem(RoomsItem{Room:"ground", Available:1})

    

    err = srv.Query("INSERT INTO objects(id, rooms) VALUES(?, ?)", gocql.TimeUUID(), rooms).Exec()

    if err != nil {

log.Fatal(err)

}

    

}

func (room *Rooms) AddItem(item RoomsItem) []RoomsItem {

room.Items = append(room.Items, item)

return room.Items

}

And now. i become the failure "cannot marshal main.Rooms into immodb.objects{room=varchar,available=int}"???

I´m really confussed;-))

[chris.b...@swiftkey.com]

Hi, it looks like from your last example that you are trying to insert a list of rooms into a single rooms column which the driver doesn't know how to convert to the wire format. Instead try using a batch or executing each query one by one for each row.