如何修改json值

Question

我有这样的JSON消息：

{"name":"Kallel", "birthdate":"01/01/2012"}

JSON消息的处理是通过Shell脚本（sh）完成的

我用以下方式加载JSON消息

json_init
json_load "$msg"

然后，我要编辑"birthdate"值。 如何使用json脚本功能呢？ 无需重建JSON消息。 我只想编辑值。

我正在使用此JSON脚本文件来包含JSON函数：

jshn.sh （来自开源libubox）

# functions for parsing and generating json

_json_get_var() {
    local ___dest="$1"
    local ___var="$2"
    eval "$___dest=\"\$${JSON_PREFIX}$___var\""
}

_json_set_var() {
    local ___var="$1"
    local ___val="$2"
    eval "${JSON_PREFIX}$___var=\"\$___val\""
}

_jshn_append() {
    local __var="$1"
    local __value="$2"
    local __sep="${3:- }"
    local __old_val

    _json_get_var __old_val "$__var"
    __value="${__old_val:+$__old_val$__sep}$__value"
    _json_set_var "$__var" "$__value"
}

_json_export() {
    local __var="${JSON_PREFIX}$1"
    local __val="$2"

    export -- "$__var=$__val"
    _jshn_append "JSON_UNSET" "$__var"
}

_json_add_key() {
    local table="$1"
    local var="$2"
    _jshn_append "KEYS_${table}" "$var"
}

_get_var() {
    local __dest="$1"
    local __var="$2"
    eval "$__dest=\"\$$__var\""
}

_set_var() {
    local __var="$1"
    local __val="$2"
    eval "$__var=\"\$__val\""
}

_json_inc() {
    local _var="$1"
    local _dest="$2"
    local _seq

    _json_get_var _seq "$_var"
    _seq="$((${_seq:-0} + 1))"
    _json_set_var "$_var" "$_seq"
    [ -n "$_dest" ] && _set_var "$_dest" "$_seq"
}

_json_stack_push() {
    local new_cur="$1"
    local cur

    _json_get_var cur JSON_CUR
    _jshn_append JSON_STACK "$cur"
    _json_set_var JSON_CUR "$new_cur"
}

_json_add_generic() {
    local type="$1"
    local var="$2"
    local val="$3"
    local cur="$4"

    [ -n "$cur" ] || _json_get_var cur JSON_CUR

    if [ "${cur%%[0-9]*}" = "JSON_ARRAY" ]; then
        _json_inc "SEQ_$cur" var
    else
        local name="${var//[^a-zA-Z0-9_]/_}"
        [[ "$name" == "$var" ]] || _json_export "NAME_${cur}_${name}" "$var"
        var="$name"
    fi

    _json_export "${cur}_$var" "$val"
    _json_export "TYPE_${cur}_$var" "$type"
    _json_add_key "$cur" "$var"
}

_json_add_table() {
    local name="$1"
    local type="$2"
    local itype="$3"
    local cur new_cur
    local seq

    _json_get_var cur JSON_CUR
    _json_inc JSON_SEQ seq

    local table="JSON_$itype$seq"
    _json_export "UP_$table" "$cur"
    _json_export "KEYS_$table" ""
    [ "$itype" = "ARRAY" ] && _json_export "SEQ_$table" ""
    _json_stack_push "$table"

    _json_get_var new_cur JSON_CUR
    _json_add_generic "$type" "$1" "$new_cur" "$cur"
}

_json_close_table() {
    local stack new_stack

    _json_get_var stack JSON_STACK
    _json_set_var JSON_CUR "${stack##* }"
    new_stack="${stack% *}"
    [[ "$stack" == "$new_stack" ]] && new_stack=
    _json_set_var JSON_STACK "$new_stack"
}

json_set_namespace() {
    local _new="$1"
    local _old="$2"

    [ -n "$_old" ] && _set_var "$_old" "$JSON_PREFIX"
    JSON_PREFIX="$_new"
}

json_cleanup() {
    local unset

    _json_get_var unset JSON_UNSET
    [ -n "$unset" ] && eval "unset $unset"

    unset \
        ${JSON_PREFIX}JSON_SEQ \
        ${JSON_PREFIX}JSON_STACK \
        ${JSON_PREFIX}JSON_CUR \
        ${JSON_PREFIX}JSON_UNSET \
        ${JSON_PREFIX}KEYS_JSON_VAR \
        ${JSON_PREFIX}TYPE_JSON_VAR
}

json_init() {
    json_cleanup
    export -- \
        ${JSON_PREFIX}JSON_SEQ=0 \
        ${JSON_PREFIX}JSON_STACK= \
        ${JSON_PREFIX}JSON_CUR="JSON_VAR" \
        ${JSON_PREFIX}JSON_UNSET="" \
        ${JSON_PREFIX}KEYS_JSON_VAR= \
        ${JSON_PREFIX}TYPE_JSON_VAR=
}

json_add_object() {
    _json_add_table "$1" object TABLE
}

json_close_object() {
    _json_close_table
}

json_add_array() {
    _json_add_table "$1" array ARRAY 
}

json_close_array() {
    _json_close_table
}

json_add_string() {
    _json_add_generic string "$1" "$2"
}

json_add_int() {
    _json_add_generic int "$1" "$2"
}

json_add_boolean() {
    _json_add_generic boolean "$1" "$2"
}

# functions read access to json variables

json_load() {
    eval `jshn -r "$1"`
}

json_dump() {
    jshn "$@" ${JSON_PREFIX:+-p "$JSON_PREFIX"} -w 
}

json_get_type() {
    local __dest="$1"
    local __cur

    _json_get_var __cur JSON_CUR
    local __var="${JSON_PREFIX}TYPE_${__cur}_${2//[^a-zA-Z0-9_]/_}"
    eval "export -- \"$__dest=\${$__var}\"; [ -n \"\${$__var+x}\" ]"
}

json_get_var() {
    local __dest="$1"
    local __cur

    _json_get_var __cur JSON_CUR
    local __var="${JSON_PREFIX}${__cur}_${2//[^a-zA-Z0-9_]/_}"
    eval "export -- \"$__dest=\${$__var}\"; [ -n \"\${$__var+x}\" ]"
}

json_get_vars() {
    while [ "$#" -gt 0 ]; do
        local _var="$1"; shift
        json_get_var "$_var" "$_var"
    done
}

json_select() {
    local target="$1"
    local type
    local cur

    [ -z "$1" ] && {
        _json_set_var JSON_CUR "JSON_VAR"
        return 0
    }
    [[ "$1" == ".." ]] && {
        _json_get_var cur JSON_CUR
        _json_get_var cur "UP_$cur"
        _json_set_var JSON_CUR "$cur"
        return 0
    }
    json_get_type type "$target"
    case "$type" in
        object|array)
            json_get_var cur "$target"
            _json_set_var JSON_CUR "$cur"
        ;;
        *)
            echo "WARNING: Variable '$target' does not exist or is not an array/object"
            return 1
        ;;
    esac
}

json_is_a() {
    local type

    json_get_type type "$1"
    [ "$type" = "$2" ]
}

Answer 1

您最好使用带有经过测试的真实JSON解析器的语言，例如Perl：

#!/usr/bin/perl
use strict;
use warnings;
use JSON;
# not required, just for this demonstration:
use Time::Piece;
use Time::Seconds;

while (<>) {
    my $json = decode_json $_;

    # now, do something with the data:
    my $bday = Time::Piece->strptime($json->{birthdate}, "%m/%d/%Y");
    $bday -= ONE_MONTH;
    $json->{birthdate} = $bday->strftime("%m/%d/%Y");

    # and print it back out
    print encode_json($json), "\n";
}

perl json.pl <<END
{"name":"Kallel", "birthdate":"01/01/2012"}
END

{"birthdate":"12/01/2011","name":"Kallel"}