rob05c commented on a change in pull request #2365: Add TO Go api helpers
URL: 
https://github.com/apache/incubator-trafficcontrol/pull/2365#discussion_r194777789
 
 

 ##########
 File path: traffic_ops/traffic_ops_golang/api/api.go
 ##########
 @@ -0,0 +1,304 @@
+package api
+
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+import (
+       "context"
+       "database/sql"
+       "encoding/json"
+       "errors"
+       "fmt"
+       "io"
+       "net/http"
+       "strconv"
+       "strings"
+
+       "github.com/apache/incubator-trafficcontrol/lib/go-log"
+       "github.com/apache/incubator-trafficcontrol/lib/go-tc"
+       
"github.com/apache/incubator-trafficcontrol/traffic_ops/traffic_ops_golang/auth"
+       
"github.com/apache/incubator-trafficcontrol/traffic_ops/traffic_ops_golang/config"
+       
"github.com/apache/incubator-trafficcontrol/traffic_ops/traffic_ops_golang/dbhelpers"
+
+       "github.com/jmoiron/sqlx"
+)
+
+const DBContextKey = "db"
+const ConfigContextKey = "context"
+
+// WriteResp takes any object, serializes it as JSON, and writes that to w. 
Any errors are logged and written to w via tc.GetHandleErrorsFunc.
+// This is a helper for the common case; not using this in unusual cases is 
perfectly acceptable.
+func WriteResp(w http.ResponseWriter, r *http.Request, v interface{}) {
+       resp := struct {
+               Response interface{} `json:"response"`
+       }{v}
+       WriteRespRaw(w, r, resp)
+}
+
+// WriteRespRaw acts like WriteResp, but doesn't wrap the object in a 
`{"response":` object. This should be used to respond with endpoints which 
don't wrap their response in a "response" object.
+func WriteRespRaw(w http.ResponseWriter, r *http.Request, v interface{}) {
+       bts, err := json.Marshal(v)
+       if err != nil {
+               log.Errorf("marshalling JSON (raw) for %T: %v", v, err)
+               tc.GetHandleErrorsFunc(w, r)(http.StatusInternalServerError, 
errors.New(http.StatusText(http.StatusInternalServerError)))
+               return
+       }
+       w.Header().Set("Content-Type", "application/json")
+       w.Write(bts)
+}
+
+// WriteRespVals is like WriteResp, but also takes a map of root-level values 
to write. The API most commonly needs these for meta-parameters, like size, 
limit, and orderby.
+// This is a helper for the common case; not using this in unusual cases is 
perfectly acceptable.
+func WriteRespVals(w http.ResponseWriter, r *http.Request, v interface{}, vals 
map[string]interface{}) {
+       vals["response"] = v
+       respBts, err := json.Marshal(vals)
+       if err != nil {
+               log.Errorf("marshalling JSON for %T: %v", v, err)
+               tc.GetHandleErrorsFunc(w, r)(http.StatusInternalServerError, 
errors.New(http.StatusText(http.StatusInternalServerError)))
+               return
+       }
+       w.Header().Set("Content-Type", "application/json")
+       w.Write(respBts)
+}
+
+// HandleErr handles an API error, writing the given statusCode and userErr to 
the user, and logging the sysErr. If userErr is nil, the text of the HTTP 
statusCode is written.
+// This is a helper for the common case; not using this in unusual cases is 
perfectly acceptable.
+func HandleErr(w http.ResponseWriter, r *http.Request, statusCode int, userErr 
error, sysErr error) {
+       if sysErr != nil {
+               log.Errorln(r.RemoteAddr + " " + sysErr.Error())
+       }
+       if userErr == nil {
+               userErr = errors.New(http.StatusText(statusCode))
+       }
+       respBts, err := json.Marshal(tc.CreateErrorAlerts(userErr))
+       if err != nil {
+               log.Errorln("marshalling error: " + err.Error())
+               *r = *r.WithContext(context.WithValue(r.Context(), 
tc.StatusKey, http.StatusInternalServerError))
+               w.Write([]byte(http.StatusText(http.StatusInternalServerError)))
+               return
+       }
+       *r = *r.WithContext(context.WithValue(r.Context(), tc.StatusKey, 
statusCode))
+       w.Header().Set(tc.ContentType, tc.ApplicationJson)
+       w.Write(respBts)
+}
+
+// RespWriter is a helper to allow a one-line response, for endpoints with a 
function that returns the object that needs to be written and an error.
+// This is a helper for the common case; not using this in unusual cases is 
perfectly acceptable.
+func RespWriter(w http.ResponseWriter, r *http.Request) func(v interface{}, 
err error) {
+       return func(v interface{}, err error) {
+               if err != nil {
+                       HandleErr(w, r, http.StatusInternalServerError, nil, 
err)
+                       return
+               }
+               WriteResp(w, r, v)
+       }
+}
+
+// RespWriterVals is like RespWriter, but also takes a map of root-level 
values to write. The API most commonly needs these for meta-parameters, like 
size, limit, and orderby.
+// This is a helper for the common case; not using this in unusual cases is 
perfectly acceptable.
+func RespWriterVals(w http.ResponseWriter, r *http.Request, vals 
map[string]interface{}) func(v interface{}, err error) {
+       return func(v interface{}, err error) {
+               if err != nil {
+                       HandleErr(w, r, http.StatusInternalServerError, nil, 
err)
+                       return
+               }
+               WriteRespVals(w, r, v, vals)
+       }
+}
+
+// WriteRespAlert creates an alert, serializes it as JSON, and writes that to 
w. Any errors are logged and written to w via tc.GetHandleErrorsFunc.
+// This is a helper for the common case; not using this in unusual cases is 
perfectly acceptable.
+func WriteRespAlert(w http.ResponseWriter, r *http.Request, level 
tc.AlertLevel, msg string) {
+       resp := struct{ tc.Alerts }{tc.CreateAlerts(level, msg)}
+       respBts, err := json.Marshal(resp)
+       if err != nil {
+               HandleErr(w, r, http.StatusInternalServerError, nil, 
errors.New("marshalling JSON: "+err.Error()))
+               return
+       }
+       w.Header().Set(tc.ContentType, tc.ApplicationJson)
+       w.Write(respBts)
+}
+
+// IntParams parses integer parameters, and returns map of the given params, 
or an error if any integer param is not an integer. The intParams may be nil if 
no integer parameters are required. Note this does not check existence; if an 
integer paramter is required, it should be included in the requiredParams given 
to NewInfo.
+// This is a helper for the common case; not using this in unusual cases is 
perfectly acceptable.
+func IntParams(params map[string]string, intParamNames []string) 
(map[string]int, error) {
+       intParams := map[string]int{}
+       for _, intParam := range intParamNames {
+               valStr, ok := params[intParam]
+               if !ok {
+                       continue
+               }
+               valInt, err := strconv.Atoi(valStr)
+               if err != nil {
+                       return nil, errors.New("parameter '" + intParam + "'" + 
" not an integer")
+               }
+               intParams[intParam] = valInt
+       }
+       return intParams, nil
+}
+
+// ParamsHaveRequired checks that params have all the required parameters, and 
returns nil on success, or an error providing information on which params are 
missing.
+func ParamsHaveRequired(params map[string]string, required []string) error {
+       missing := []string{}
+       for _, requiredParam := range required {
+               if _, ok := params[requiredParam]; !ok {
+                       missing = append(missing, requiredParam)
+               }
+       }
+       if len(missing) > 0 {
+               return errors.New("missing required parameters: " + 
strings.Join(missing, ", "))
+       }
+       return nil
+}
+
+// StripParamJSON removes ".json" trailing any parameter value, and returns 
the modified params.
+// This allows the API handlers to transparently accept /id.json routes, as 
allowed by the 1.x API.
+func StripParamJSON(params map[string]string) map[string]string {
+       for name, val := range params {
+               if strings.HasSuffix(val, ".json") {
+                       params[name] = val[:len(val)-len(".json")]
+               }
+       }
+       return params
+}
+
+// AllParams takes the request (in which the router has inserted context for 
path parameters), and an array of parameters required to be integers, and 
returns the map of combined parameters, and the map of int parameters; or a 
user or system error and the HTTP error code. The intParams may be nil if no 
integer parameters are required.
+// This is a helper for the common case; not using this in unusual cases is 
perfectly acceptable.
+func AllParams(req *http.Request, required []string, ints []string) 
(map[string]string, map[string]int, error, error, int) {
+       params, err := GetCombinedParams(req)
+       if err != nil {
+               return nil, nil, errors.New("getting combined URI parameters: " 
+ err.Error()), nil, http.StatusBadRequest
+       }
+       params = StripParamJSON(params)
+       if err := ParamsHaveRequired(params, required); err != nil {
+               return nil, nil, errors.New("required parameters missing: " + 
err.Error()), nil, http.StatusBadRequest
+       }
+       intParams, err := IntParams(params, ints)
+       if err != nil {
+               return nil, nil, nil, errors.New("getting integer parameters: " 
+ err.Error()), http.StatusInternalServerError
+       }
+       return params, intParams, nil, nil, 0
+}
+
+type ParseValidator interface {
+       Validate(tx *sql.Tx) error
+}
+
+// Decode decodes a JSON object from r into the given v, validating and 
sanitizing the input. This helper should be used in API endpoints, rather than 
the json package, to safely decode and validate PUT and POST requests.
 
 Review comment:
   That's the idiom. This code can't guarantee that, of course.

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