golang Couchbase n1ql查询将参数传递给？

Question

I'm trying to find a way to pass parameters to query, but not quite sure how. The API on the web site looks a little bit outdated?

myQuery := gocb.NewN1qlQuery("SELECT * FROM default")
rows, err := myBucket.ExecuteN1qlQuery(myQuery)
if err != nil {
    fmt.Printf("N1QL query error: %s
", err)
}
var row interface{}
for rows.Next(&row) {
    fmt.Printf("Row: %+v
", row)
}
if err := rows.Close(); err != nil {
    fmt.Printf("N1QL query error: %s
", err)
}

Because, actually ExecuteN1qlQuery takes two params:

func (b *Bucket) ExecuteN1qlQuery(q *N1qlQuery, params interface{}) (ViewResults, error)

I am not sure just how to use it... Like I would like to create a query with placeholders, and pass values to ExecuteN1qlQuery via params. Like with SQL (prepare -> execute). For example something like that:

    myQuery := gocb.NewN1qlQuery("SELECT * FROM default where a=? and b=?")
    rows, err := myBucket.ExecuteN1qlQuery(myQuery,[]string{"b","c"})
    if err != nil {
        fmt.Printf("N1QL query error: %s
", err)
    }
    var row interface{}
    for rows.Next(&row) {
        fmt.Printf("Row: %+v
", row)
    }
    if err := rows.Close(); err != nil {
        fmt.Printf("N1QL query error: %s
", err)
    }

Answer 1

The example you posted for how to do do this is from our developer guide repo on github:

https://github.com/couchbaselabs/devguide-examples/blob/master/go/query-placeholders.go.

Basically, you're using $ which references an interface and a corresponding positional parameter beginning with 1.

For your example it would look something like:

// Setup a new query with a placeholder
myQuery := gocb.NewN1qlQuery("SELECT * FROM default where a=$1 and b=$2")

// Setup an array for parameters
var myParams []interface{}
myParams = append(myParams,"foo")
myParams = append(myParams,"bar")

// Execute Query
rows, err := bucket.ExecuteN1qlQuery(myQuery, myParams)
if err != nil {
    fmt.Println("ERROR EXECUTING N1QL QUERY:", err)
}

// Iterate through rows and print output
var row interface{}
for rows.Next(&row) {
    fmt.Printf("Results: %+v
", row)
}