How to set boolean value in curl command used bash script

Question

I need set into variable true/false value and send him into json with curl command:

name=$1
sx=$2

`curl -d '{"name":"'"$name"'", "sex":true}' -H "Content-Type: application/json" -X POST http://localhost:8080/setacc`

Variable sx accepts the value male or female how to set the appropriate boolean value into sex variable?

Which one is the _true_ sex? Male or female? Maybe there are other values? — PerlDuck, Nov 16 '18 at 19:50
@PerlDuck it is do not matter. It is can be `0` - true, or `1` - false — Valentyn Hruzytskyi, Nov 16 '18 at 19:52
The USA is awake and they're a bunch of puritans. A bit later New Zealand and Australia will wake up and they've got a great sense of humour, so they'll give you a sympathy **+1** as well. — Fabby, Nov 16 '18 at 20:48
Naah, never mind! I think the question was just downvoted because of the mixture of male/female, true/false, and 0/1. — PerlDuck, Nov 16 '18 at 20:49
Anyone trying to use this web API has to remember which of two arbitrary labels was assigned to `male` and `female`, instead of just using `male` and `female`. I'm sure that'll never get confusing. Good on you for trying to make it a little more usable from your tool. — Nic, Nov 16 '18 at 23:57
@NicHartley, it is do not matter. I need know, how to set value in BOOLEAN variable. I know how to set string value! - `"name":"'"$name"'"` But that not working with BOOLEAN — Valentyn Hruzytskyi, Nov 17 '18 at 08:50
Sorry that's meant to be a [humorous third boolean value: `true`, `false`, `file-not-found`](https://thedailywtf.com/articles/What_Is_Truth_0x3f_). — Dennis Williamson, Nov 17 '18 at 10:36

PerlDuck · Answer 1 · 2018-11-16T21:01:47.540

The easiest way to map the string male to either true or false (depending on your needs) and female to some other value is a simple if…then…else clause. The trick is the quoting but you already got that with the $name variable. So:

if [ "$sx" = "male" ]; then
    sex="true";     # or whatever you consider male sex to be
else
    sex="false";    # just the opposite, see above
fi

curl -d '{"name":"'"$name"'", "sex":'$sex'}' -H "Content-Type: application/json" -X POST http://localhost:8080/setacc

score 3 · Answer 2 · answered Nov 16 '18 at 20:04

In your case you use json and can use text "true" and text "false".

You need add to bash script logic:

sex="false"
if [ "$sx" = "male" ]; then
  sex="true"
fi

then run curl command with ... {"name":"'"$name"'", "sex":\"$sex\"} ... or just ... {"name":"'"$name"'", "sex":$sex} ...

Test script:

#!/bin/bash

sx="male"

sex="false"
if [ "$sx" = "male" ]; then
  sex="true"
fi

echo \"$sex\"

score 2 · Accepted Answer · answered Nov 17 '18 at 00:38

Using a variable for the whole JSON string and building it piece wise can make the quoting less cumbersome and make the curl command line more readable and easier to maintain even though the overall code is much more verbose.

Building the string is done here using the string self concatenation operator +=. Note that in json_string+=$name, for example, no quoting is necessary since there's no word splitting being performed and no special characters are present on the right hand side.

You can use an associative array to look up the value you want based on the provided key. Here I'm assigning the pairs individually. Below I'll show how to do them in one assignment.

name=$1
sx=$2

declare -A sexes
sexes[male]=false
sexes[female]=true

json_string='{"name":"'
json_string+=$name
json_string+='", "sex":'
json_string+=${sexes[$sx]}
json_string+='}'

curl -d "$json_string" " -H "Content-Type: application/json" -X POST http://localhost:8080/setacc

You can break the JSON up even more to make it look a little more structured in the code (the resulting string contents will still be a single-line string). Ideally, if you're using more complicated JSON than this you should use a purpose built JSON tool for building the structure.

Here's how you can make the associative array declaration and assignment all at once. The first example is on one line and the second is on multiple lines - again for improved readability and maintainability.

declare -A sexes='([female]="true" [male]="false")'

declare -A sexes='(
    [female]="true"
    [male]="false"
)'

How to set boolean value in curl command used bash script

3 Answers3