Storing html template as text field in DB using golang - html

I'm a beginner in Go and Echo.
I am required to store a html template(email template) , which will also have some details passed as context. So that it can be stored into body column (text in MySQL) and will be triggered later.
if user.Email !=""{
visitingDetails := H{"user_name" : user.Fname,
"location" : location.Name,
"visitor_company": visitor.Company,
"visitor_name" : visitor.Fname +" "+visitor.Lname,
"visitor_phone" : visitor.Phone,
"visitor_email" : visitor.Email,
"visitor_fname" : visitor.Fname,
"visitor_image" : visitor.ProfilePicture,
}
subject := visitor.Fname +" has come to visit you at the reception"
body := c.Render(http.StatusOK,"email/user_notify_email.html",visitingDetails)
emailJob := models.EmailJob{Recipients: visitor.Email , Subject: subject, Body: body}
db.Create(&emailJob)
if db.NewRecord(emailJob){
fmt.Println("Unable to send email")
}
}
The EmailJob
type EmailJob struct {
Id int
Recipients string
Subject string
Body string
Sent int
Error string
}
func (t *Template) Render(w io.Writer, name string, data interface{}, c echo.Context) error {
return t.templates.ExecuteTemplate(w, name, data)
}
body := c.Render(http.StatusOK,"email/user_notify_email.html",visitingDetails)
this line gives error as it returns an error for render.
I am not sure how I will I do it? I hope I made it clear. A little help will be much appreciated.

You are using context.Render method incorrectly.
https://github.com/labstack/echo/blob/master/context.go#L111
// Render renders a template with data and sends a text/html response with status
// code. Renderer must be registered using `Echo.Renderer`.
Render(code int, name string, data interface{}) error
The Render methods renders the template and sends it as a response.
This method returns an error value, if something unexpected happens, this error value is a description of it. Otherwise, it is equal to nil.
See: https://golang.org/pkg/errors/
In order to use Renderer, you must register it and you can use that registered renderer to get rendered template text and save it in DB.
You can see example renderer in unit tests of Echo framework: https://github.com/labstack/echo/blob/master/context_test.go#L23
Hope this helps.

After doing a few things and understanding template in golang.
I came up with a solution like this.
t, err := template.ParseFiles("templates/email/user_notify_email.html")
if err != nil {
fmt.Println("Error happend")
fmt.Println(err)
return c.JSON(http.StatusOK, data)
}
buf := new(bytes.Buffer)
if err = t.Execute(buf, visitingDetails); err != nil {
fmt.Println(err)
}
body := buf.String()
And now this body can be stored. Body has rendered template that I required.
Much credit goes to this article https://medium.com/#dhanushgopinath/sending-html-emails-using-templates-in-golang-9e953ca32f3d

Related

How to parse protocol buffer message and create json out of it?

Here is my minimal .proto file:
syntax = "proto3";
message getDhtParams {}
message DhtContents {
string dht_contents=1;
}
service MyApp {
rpc getDhtContent(getDhtParams) returns (DhtContents) {}
}
Two things to note related to the above proto file:
It is a minimal file. There is a lot more to it.
The server is already generated and running. The server is implemented in Python.
I am writing client in Go. And this is the fetching code I have come up with:
func fetchDht() (*pb.DhtContents, error) {
// Set up a connection to the server.
address := "localhost:9998"
conn, err := grpc.Dial(address, grpc.WithTransportCredentials(insecure.NewCredentials()))
if err != nil {
log.Fatalf("did not connect: %v", err)
}
defer conn.Close()
client := pb.NewMyAppClient(conn)
ctx, cancel := context.WithTimeout(context.Background(), time.Second)
defer cancel()
r, err := client.GetDhtContent(ctx, &pb.GetDhtParams{})
if err != nil {
return nil, errors.New("could not get dht contents")
}
return r, nil
}
For sake of simplicity, I have tripped down the output, but the output looks something like this:
dht_contents:"{'node_ids': ['dgxydhlqoopevxv'], 'peer_addrs': [['192.168.1.154', '41457']], 'peer_meta': [{'peer_id': {'nodeID': 'dgxydhlqoopevxv', 'key': 'kdlvjdictuvgxspwkdizqryr', 'mid': 'isocvavbtzkxeigkkrubzkcx', 'public_key': 'uhapwxnfeqqmnojsaijghhic', '_address': 'xklqlebqngpkxb'}, 'ip_addrs': ['192.168.1.154', '41457'], 'services': [{'service_input': '', 'service_output': '', 'price': 0}], 'timestamp': 1661319968}]}"
A few things to note about this response:
It starts with dht_contents: which I know is a field of DhtContents message.
This could be an issue from the server side; in that case I will inform the service developer. But the json enclosed is not a valid JSON as it uses single quotes.
My questions:
What is an elegant way to deal with that dht_contents? There must be the protobuf/grpc way. I aim to get the contents between double quotes.
How do I convert the content to JSON? I have already created the struct to unmarshal.
It would be enough if I am also able to convert the response which is of type *pb.DhtContents to []byte, from there I can convert it to JSON.
The generated code should have a method which will get rid of dht_contents:" from the start and " from the end.
In your case, that method should be called GetDhtContents().
You can modify your fetchDht function to something like this:
func fetchDht() (string, error) {
address := "localhost:9998"
// ...
if err != nil {
return nil, errors.New("could not get dht contents")
}
return r.GetDhtContents(), nil
}
From there on, you can work on making it a valid JSON by replacing single quotes to double quotes. Or it may be handled on the service end.
there is the methods generated by proto file to get the content from the result(the "r"), then use r.Get..., you could get the content.
convert string to the type you want.
suggest:
change proto type to bytes
then json.Unmarshal([r.Get...],[dst])

Is it possible to Unmarshall a JSON which has varying field?

I am tring to get League of Legends champion informations from LOL static database. Link is given below.
Get info for specific hero
The problem is that i can only make request by hero names and all JSON responses are different from each other by only one field which is a "main" field; hero name. You can find problematic field as highlighted below:
Also tree respresentation:
My goal is to get all hero informations with iteration by range of known hero names as slice. You can check the code. I need only a couple of fields but the main tag is varies with every new request.
func GetHeroInfo(heroName string) *LolHeroInfo {
getUrl := fmt.Sprintf("http://ddragon.leagueoflegends.com/cdn/12.2.1/data/en_US/champion/%s.json", heroName)
fmt.Println(getUrl)
resp, err := http.Get(getUrl)
if err != nil {
fmt.Println(err)
return nil
}
defer resp.Body.Close()
read, err := io.ReadAll(resp.Body)
if err != nil {
fmt.Println(err)
return nil
}
heroGoverted := LolHeroInfo{}
err = json.Unmarshal(read, &heroGoverted)
if err != nil {
fmt.Println("unmarshall failed:", err)
return nil
}
return &heroGoverted }
Struct type LolHeroInfo is structifyed from this link: mholt's JSON to struct
You can check JSON response for another hero eg: JSON response for Annie .
Is there any way to make an agnostic struct field/tag for a JSON field. I believe this will be very hard because encoding/json package needs to check for field for particular tag in that JSON but maybe you encountered this kind of problem before. Creating separate struct for each hero is impossible so i will drop this case if i can't find a solution.
Thanks in advance for help.
Since you know it's just a single unknown key, you could just decode into a map[string]LolHeroInfo for the Data field, then do
heroGoverted := LolHeroInfo{}
for _, v := range decoded.Data {
heroGoverted = v
}
To solve problem, I used #dave 's solution.
I breake main struct into two separate struct. This way varying JSON field eliminated:
type LolHeroInfo struct {
Type string `json:"type"`
Format string `json:"format"`
Version string `json:"version"`
Data map[string]HeroInfoStruct `json:"data"`
}
heroInfo := lib.GetHeroInfo(lolHeroes[i])
for _, v := range heroInfo.Data { //unmarshalled to first struct
a := lib.HeroInfoStruct{} //data field; second struct
a = v
fmt.Println(a.Lore)// now i can reach to every field that i need
}

In golang json.Unmarshal() works in playground/copy pasted JSON but not in actual code

I am writing a program in Golang that interfaces with a modified version of the barefoot mapmatching library which returns results in json via netcat.
My in my actual code json.Unmarshal will only parse the response to the nil value of the struct. But if print the json to console (see code snippet below) and copy paste into goplayground it behaves as expected.
I am wondering if this is an encoding issue that is bypassed when I copy paste from the console as a result.
How do I get my code to process the same string as it is received from barefoot as when it is copy pasted from the console?
Here is the relevant code snippet (structs are identical to goplayground)
body := io_func(conn, cmd)
var obvs []Json_out
json.Unmarshal([]byte(body), &obvs)
fmt.Println(body)
fmt.Println(obvs)
and io_func() if relevant (the response is two lines, with a message on the first and a json string on the second)
func io_func(conn net.Conn, cmd string) string {
fmt.Fprintf(conn, cmd+"\n")
r := bufio.NewReader(conn)
header, _ := r.ReadString('\n')
if header == "SUCCESS\n" {
resp, _ := r.ReadString('\n')
return resp
} else {
return ""
}
}
Following Cerise Limón's advice to properly handle error messages I determined the osm_id value in the JSON was being parsed by json.Unmarshall as number when taking the string from io_func(), although it wasn't doing so when the string was passed in manually in the playground example. Although I don't understand why this is so I would have picked it up with proper error handling.
I altered barefoot code to return the osm_id explicitly in inverted commas since, although only ever composed of digits, I only use it as a string. It now works as expected. Equally I could have changed the type in the struct and convert in Go as needed.
The io_func function creates and discards a bufio.Reader and data the reader may have buffered. If the application calls io_func more than once, then the application may be discarding data read from the network. Fix by creating a single bufio.Reader outside the function and pass that single reader to each invocation of io_func.
Always check and handle errors. The error returned from any of these functions may point you in the right direction for a fix.
func io_func(r *bufio.Reader, conn net.Conn, cmd string) (string, error) {
fmt.Fprintf(conn, cmd+"\n")
header, err := r.ReadString('\n')
if err != nil {
return "", err
}
if header == "SUCCESS\n" {
return r.ReadString('\n')
}
return "", nil
}
...
r := bufio.NewReader(conn)
body, err := io_func(r, conn, cmd)
if err != nil {
// handle error
}
var obvs []Json_out
err = json.Unmarshal([]byte(body), &obvs)
if err != nil {
// handle error
}
fmt.Println(body)
fmt.Println(obvs)
// read next
body, err = io_func(r, conn, cmd)
if err != nil {
// handle error
}
The application uses newline to terminate the JSON body, but newline is valid whitespace in JSON. If the peer includes a newline in the JSON, then the application will read a partial message.

Unit testing http json response in Golang

I am using gin as my http server and sending back an empty array in json as my response:
c.JSON(http.StatusOK, []string{})
The resulting json string I get is "[]\n". The newline is added by the json Encoder object, see here.
Using goconvey, I could test my json like
So(response.Body.String(), ShouldEqual, "[]\n")
But is there a better way to generate the expected json string than just adding a newline to all of them?
You should first unmarshal the body of the response into a struct and compare against the resulting object. Example:
result := []string{}
if err := json.NewDecoder(response.Body).Decode(&result); err != nil {
log.Fatalln(err)
}
So(len(result), ShouldEqual, 0)
You may find jsonassert useful.
It has no dependencies outside the standard library and allows you to verify that JSON strings are semantically equivalent to a JSON string you expect.
In your case:
// white space is ignored, no need for \n
jsonassert.New(t).Assertf(response.Body().String(), "[]")
It can handle any form of JSON, and has very friendly assertion error messages.
Disclaimer: I wrote this package.
Unmarshal the body into a struct and the use Gocheck's DeepEquals
https://godoc.org/launchpad.net/gocheck
I made it this way. Because I don't want to include an extra library.
tc := testCase{
w: httptest.NewRecorder(),
wantResponse: mustJson(t, map[string]string{"message": "unauthorized"}),
}
...
if tc.wantResponse != tc.w.Body.String() {
t.Errorf("want %s, got %s", tt.wantResponse, tt.w.Body.String())
}
...
func mustJson(t *testing.T, v interface{}) string {
t.Helper()
out, err := json.Marshal(v)
if err != nil {
t.Fatal(err)
}
return string(out)
}

Is it possible to create email templates with CSS in Google App Engine Go?

I am creating a GAE Golang application that will be notifying users of what is happening in the system. Since I want the emails to look nice, I am already using HTMLBody. However, as I'm creating more and more complex emails, I would like to start using something like html/template to crease nice looking emails with CSS and so forth. However, I'm not sure how I can do Template.Execute to turn it into HTMLBody string that can be sent.
How can I use something like html/template to create HTML emails to use with appengine/mail ?
You can render the template to a temporary byte buffer, like this:
var tmpl = template.Must(template.ParseFiles("templates/email.html"))
buff := new(bytes.Buffer)
if err = tmpl.Execute(buff, struct{ Name string }{"Juliet"}); err != nil {
panic(err.Error())
}
msg := &mail.Message{
Sender: "romeo#montague.com",
To: []string{"Juliet <juliet#capulet.org>"},
Subject: "See you tonight",
Body: "...you put here the non-HTML part...",
HTMLBody: buff.String(),
}
c := appengine.NewContext(r)
if err := mail.Send(c, msg); err != nil {
c.Errorf("Alas, my user, the email failed to sendeth: %v", err)
}