super-graph/core/resolve.go

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package core
import (
"fmt"
"io/ioutil"
"net/http"
"strings"
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"github.com/cespare/xxhash/v2"
"github.com/dosco/super-graph/core/internal/psql"
"github.com/dosco/super-graph/jsn"
)
type resolvFn struct {
IDField []byte
Path [][]byte
Fn func(h http.Header, id []byte) ([]byte, error)
}
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func (sg *SuperGraph) initResolvers() error {
var err error
sg.rmap = make(map[uint64]*resolvFn)
for _, t := range sg.conf.Tables {
err = sg.initRemotes(t)
if err != nil {
break
}
}
if err != nil {
return fmt.Errorf("failed to initialize resolvers: %v", err)
}
return nil
}
func (sg *SuperGraph) initRemotes(t Table) error {
h := xxhash.New()
for _, r := range t.Remotes {
// defines the table column to be used as an id in the
// remote request
idcol := r.ID
// if no table column specified in the config then
// use the primary key of the table as the id
if len(idcol) == 0 {
pcol, err := sg.pc.IDColumn(t.Name)
if err != nil {
return err
}
idcol = pcol.Key
}
idk := fmt.Sprintf("__%s_%s", t.Name, idcol)
// register a relationship between the remote data
// and the database table
val := &psql.DBRel{Type: psql.RelRemote}
val.Left.Col = idcol
val.Right.Col = idk
err := sg.pc.AddRelationship(sanitize(r.Name), t.Name, val)
if err != nil {
return err
}
// the function thats called to resolve this remote
// data request
fn := buildFn(r)
path := [][]byte{}
for _, p := range strings.Split(r.Path, ".") {
path = append(path, []byte(p))
}
rf := &resolvFn{
IDField: []byte(idk),
Path: path,
Fn: fn,
}
// index resolver obj by parent and child names
sg.rmap[mkkey(h, r.Name, t.Name)] = rf
// index resolver obj by IDField
sg.rmap[xxhash.Sum64(rf.IDField)] = rf
}
return nil
}
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func buildFn(r Remote) func(http.Header, []byte) ([]byte, error) {
reqURL := strings.Replace(r.URL, "$id", "%s", 1)
client := &http.Client{}
fn := func(hdr http.Header, id []byte) ([]byte, error) {
uri := fmt.Sprintf(reqURL, id)
req, err := http.NewRequest("GET", uri, nil)
if err != nil {
return nil, err
}
if host, ok := hdr["Host"]; ok {
req.Host = host[0]
}
for _, v := range r.SetHeaders {
req.Header.Set(v.Name, v.Value)
}
for _, v := range r.PassHeaders {
req.Header.Set(v, hdr.Get(v))
}
res, err := client.Do(req)
if err != nil {
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return nil, fmt.Errorf("failed to connect to '%s': %v", uri, err)
}
defer res.Body.Close()
// if r.Debug {
// reqDump, err := httputil.DumpRequestOut(req, true)
// if err != nil {
// return nil, err
// }
// resDump, err := httputil.DumpResponse(res, true)
// if err != nil {
// return nil, err
// }
// logger.Debug().Msgf("Remote Request Debug:\n%s\n%s",
// reqDump, resDump)
// }
if res.StatusCode != 200 {
return nil,
fmt.Errorf("server responded with a %d", res.StatusCode)
}
b, err := ioutil.ReadAll(res.Body)
if err != nil {
return nil, err
}
if err := jsn.ValidateBytes(b); err != nil {
return nil, err
}
return b, nil
}
return fn
}