#How to append a string to an existing json file

34 messages · Page 1 of 1 (latest)

spare ivy
#

What do you have so far?

storm gust
#

Appending to or just editing a json is not possible as far as I know
You'd have to unmarshal it to a struct or some [string]interface{} map, add it there and then marshal it again

#

Then you may be overwriting it all

#

Can you post your code?

#

Do you write it back to file somewhere?

# 
package main

import (
    "encoding/json"
    "fmt"
)

func main() {

    jsonData1 := `{
    "Values":[
    {"Min":0.1,"Max":0.2},
    {"Min":0.5,"Max":0.65},
    {"Min":0.2,"Max":0.3}
  ]
}`

    var unmarshaledJson1 map[string]interface{}

    err := json.Unmarshal([]byte(jsonData1), &unmarshaledJson1)

    if err != nil {
        fmt.Println("Error decoding JSON:", err)
        return
    }

    unmarshaledJson1["sample"] = "new value"

    marshaledJsonDataWithAppendedValue, err := json.Marshal(unmarshaledJson1)
    if err != nil {
        fmt.Println("Error encoding JSON:", err)
        return
    }
    fmt.Println(string(marshaledJsonDataWithAppendedValue))
}

Output

{"Values":[{"Max":0.2,"Min":0.1},{"Max":0.65,"Min":0.5},{"Max":0.3,"Min":0.2}],"sample":"new value"}
#

looks completely normal to me

#

read the separate file with the same method so you would get new map[string]interface{} and I guess foreach would be good for that

# 
for k, v := range separateData {
      sample_json[k] = value
    }
    //marshal sample_json
hearty moat
#

unmarshal the input data, unmarshal the json file, merge the data with for loop.
marshal the final, merged data and write the result back to the file, overwriting the old content.

#

to overwrite, you need to truncate the file first.

storm gust
#

or os.create should be able to rewrite it

#

//todo don't get confused by shitty variable naming

#

separate data was supposed to be your other json if I understood correctly

#

look at it now, I edited it with some self explaining names

hearty moat
#

forget about the name, its not important.
4 main point:

  • input json, where the new data come from (could be any shape)
  • json file that you want to update
  • marshal
  • unmarshal
storm gust
hearty moat
#

it does not matter, the variable is just a placeholder for the input data that you need to replace with yours.

jsonData1, err:= os.ReadFile("path to your json file")
if err!=nil {panic(err)}

the rest of the code stay the same.

storm gust
#

the solution to this would be strings.split() to remove whitespaces and then something like path.join() to make a proper path out of it but it still begs a question: how do you even get something like that in a path a where are you taking your path from

cursive elm
#

Open file in truncate mode, read current json, unmarshal it, replace the values, marshal it back to the file

hearty moat
#

the fact that there is \t and \n means there is something wrong.
why don't you just copy and paste the file path from file manager?
where is the file path come from?

#

show it

cursive elm
#

Not trying to be rude but every time you come here with really simple problems that could be solved with some googling, and when we try to help/spoonfeed you, you provide vague informations which aren’t helpful at all

#

You should learn how to ask questions, provide clear context an d so on, so we can help you a bit

storm gust
#

shit happens

#

it's a magic sentence like "for educational purposes only" in drug making tutorials

hearty moat
#

we all tried.
you changed something on your code and it doesn't work. but you didn't show us your code, how could we help you to spot the mistake?
you faced an error. but you didn't show us the error message. what do you expect from us?
none of us tied to help ppl.

storm gust
#

🤨

#

it's /n, not \n which would be an escape character

cursive elm
#

😂

hearty moat
#

@noble crescent your problem is not ours, we are kind enough to help you.
you should at least, payback with kind and respecful words.
if you're stressed and you cant handle it, dont make it into a hassle for others. go to sleep and rest.

cursive elm
#

Guy is so mad he’s sending child p**n in my dms