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search.go
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search.go
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package grafana
import (
"context"
"net/http"
"path"
"github.com/segmentio/objconv"
)
// SearchHandler is the handler for the /search endpoint in the
// simple-json-datasource API.
type SearchHandler interface {
// ServeSearch is expected to implement the search functionality of a
// Grafana data source.
//
// Note: It's not really clear how search is implemented, I think the
// "target" field in the request is some kind of prefix or keyword to
// use to return a list of potential matches that can be used in a /query
// request.
ServeSearch(ctx context.Context, res SearchResponse, req *SearchRequest) error
}
// SearchHandlerFunc makes it possible to use regular function types as search
// handlers.
type SearchHandlerFunc func(context.Context, SearchResponse, *SearchRequest) error
// ServeSearch calls f, satisfies the SearchHandler interface.
func (f SearchHandlerFunc) ServeSearch(ctx context.Context, res SearchResponse, req *SearchRequest) error {
return f(ctx, res, req)
}
// SearchResponse is an interface used to respond to a search request.
type SearchResponse interface {
// WriteTarget writes target in the response, the method may be called
// multiple times.
WriteTarget(target string)
// WriteTargetValue writes the pair of target and value in the response,
// the method may be called multiple times.
WriteTargetValue(target string, value interface{})
}
// SearchRequest represents a request received on the /search endpoint.
type SearchRequest struct {
Target string
}
// NewSearchHandler returns a new http.Handler which delegates /search API calls
// to the given search handler.
func NewSearchHandler(handler SearchHandler) http.Handler {
return handlerFunc(func(ctx context.Context, enc *objconv.StreamEncoder, dec *objconv.Decoder) error {
req := searchRequest{}
res := searchResponse{enc: enc}
if err := dec.Decode(&req); err != nil {
return err
}
if err := handler.ServeSearch(ctx, &res, &SearchRequest{
Target: req.Target,
}); err != nil {
return err
}
return enc.Close()
})
}
// HandleSearch installs a handler on /search.
func HandleSearch(mux *http.ServeMux, prefix string, handler SearchHandler) {
mux.Handle(path.Join("/", prefix, "search"), NewSearchHandler(handler))
}
type searchRequest struct {
Target string `json:"target"`
}
type searchResponse struct {
enc *objconv.StreamEncoder
}
func (res *searchResponse) WriteTarget(target string) {
res.enc.Encode(target)
}
func (res *searchResponse) WriteTargetValue(target string, value interface{}) {
res.enc.Encode(struct {
Target string `json:"target"`
Value interface{} `json:"value"`
}{target, value})
}