func literalsHandler(w http.ResponseWriter, r *http.Request) {
uri := r.FormValue("uri")
q, _ := qBank.Prepare("literals", struct{ URI string }{uri})
resp, err := repo.Query(conf.QuadStore.Endpoint, q, "json")
if err != nil {
http.Error(w, err.Error(), http.StatusInternalServerError)
return
}
res, err := sparql.ParseJSON(resp)
if err != nil {
http.Error(w, err.Error(), http.StatusInternalServerError)
return
}
defer resp.Close()
if len(res.Results.Bindings) == 0 {
w.Write([]byte("No literals on resource"))
return
}
var b bytes.Buffer
b.WriteString("<table class='preview'>")
for _, s := range res.Solutions() {
b.WriteString("<tr><td>" + prefixify(&conf.Vocab.Dict, s["p"].Serialize(rdf.Turtle)) + "</td><td>")
b.WriteString(s["o"].Serialize(rdf.Turtle) + "</td></tr>")
}
b.WriteString("</table>")
w.Header().Set("Content-Type", "text/html; charset=utf-8")
w.Write(b.Bytes())
}
// mainHandler serves the resource HTML presentation, or dispatches to the
// rdfHandler or jsonHandler
func (m mainHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
if r.URL.Path == "/" {
// redirect from root to info page
http.Redirect(w, r, conf.UI.RootRedirectTo, http.StatusFound)
return
}
var uri string
resolved := false
suffix := suffixRg.FindString(r.URL.Path)
switch suffix {
case "":
break
case ".html":
uri = conf.BaseURI + strings.TrimSuffix(r.URL.Path, ".html")
resolved = true
case ".json":
jsonHandler(w, r)
return
case ".rdf":
rdfHandler(w, r)
return
default:
errorHandler(w, r,
fmt.Sprintf("Unsupported output format: %s.\n\n"+
"Valid formats are: html, json, rdf", suffix[1:]), http.StatusBadRequest)
return
}
// The URI should be an exclusive identifier of the resource; so we redirect
// to URI+.html
if !resolved {
http.Redirect(w, r, r.URL.Path+".html", http.StatusFound)
return
}
q, _ := qBank.Prepare("select",
struct {
URI string
Limit int
}{uri, conf.QuadStore.ResultsLimit})
resp, err := repo.Query(conf.QuadStore.Endpoint, q, "json")
if err != nil {
//println(err.Error())
errorHandler(w, r,
err.Error()+". Refresh to try again.\n\nYou can increase the timeout"+
" values in Fensters configuration file.", http.StatusInternalServerError)
return
}
defer resp.Close()
res, err := sparql.ParseJSON(resp)
if err != nil {
errorHandler(w, r,
"Failed to parse JSON response from remote SPARQL endpoint.",
http.StatusInternalServerError)
return
}
if len(res.Results.Bindings) == 0 {
errorHandler(w, r, "This URI has no information", http.StatusNotFound)
return
}
var maxS, maxO int
if len(res.Results.Bindings) >= conf.QuadStore.ResultsLimit {
// Fetch solution counts, if we hit the results limit
q, _ := qBank.Prepare("count", struct{ URI string }{uri})
resp, err := repo.Query(conf.QuadStore.Endpoint, q, "json")
if err == nil {
res, err := sparql.ParseJSON(resp)
if err == nil {
b := res.Bindings()
v, _ := b["maxS"][0].(rdf.Literal).Typed()
maxS = v.(int)
v, _ = b["maxO"][0].(rdf.Literal).Typed()
maxO = v.(int)
}
resp.Close()
}
}
solutions := res.Solutions()
subj := rejectWhereEmpty("o", solutions)
obj := rejectWhereEmpty("s", solutions)
data := struct {
Title string
License, LicenseURL string
Endpoint string
Name, Version, URI string
AsSubject []map[string]interface{}
AsObject []map[string]interface{}
AsSubjectSize int
AsObjectSize int
MaxSubject int
MaxObject int
Images []string
}{
findTitle(conf.UI.TitlePredicates, solutions),
conf.License,
conf.LicenseURL,
conf.QuadStore.Endpoint,
"Fenster",
string(version),
uri,
subj,
obj,
len(subj) - 1,
len(obj) - 1,
maxS,
maxO,
findImages(conf.UI.ImagePredicates, solutions),
}
buf := bufpool.Get()
defer bufpool.Put(buf)
err = templates.ExecuteTemplate(buf, "index.html", data)
if err != nil {
http.Error(w, err.Error(), http.StatusInternalServerError)
return
}
w.Header().Set("Content-Type", "text/html; charset=utf-8")
w.WriteHeader(http.StatusOK)
buf.WriteTo(w)
}
