# &adminguide;

## Overview

This module provides operations on JSON strings using JANSSON library. It has support for JSON-PATH operations.

## Dependencies

### &kamailio; Modules

The following modules must be loaded before this module:

- None

### External Libraries or Applications

The following libraries or applications must be installed before running &kamailio; with this module loaded:

- jansson (http://www.digip.org/jansson/), tested with: 2.2+

## Functions

### `jansson_get(path, src, dst)`

Copy the value at the location 'path' from the json object 'src' and store it in variable 'dst'. The path can also be a simple field name (a key), if it does not include any path separator. To retrieve the value of a field that includes path separators in the name, use jansson_get_field().

The 'src' can be a static string or a dynamic string with variables.

The path string supports dot delimited notation (e.g. foo.bar.baz), array notation (e.g. [0]), or a combination of the two (e.g. foo.bar[0][1].baz).

Returns FALSE if the data can not be parsed, TRUE otherwise.

The function can put a string, integer, null, or new json string into destination. If the path can't be found in the JSON data structure, the pvar is not changed. If it had a previous value, that value remains unchanged.

Note: For JSON-Integer values exceeding the C-Integer boundaries, a String representing the number is returned.

#### `jansson_get` usage

    ...
    if(!jansson_get("inner.deep.list[3]", "$var(myjson)", "$var(n)")) {
    	xlog("L_ERR", "Can't parse json data");
    }
    xlog("L_INFO", "foo is $var(n)");
    ...
    jansson_get("test", "{\"test\":\"abc\",\"idx\":20}", "$var(n)");
    ...

### `jansson_pv_get(key/path, srcvar, dst)`

Similar to jansson_get(), but the 'srcvar' parameter can be only a variable name.

#### `jansson_pv_get` usage

    ...
    if(!jansson_pv_get("inner.deep.list[3]", "$var(myjson)", "$var(n)")) {
    	xlog("L_ERR", "Can't parse json data");
    }
    xlog("L_INFO", "foo is $var(n)");
    ...

### `jansson_set(type, key/path, value, result)`

Insert 'value' as 'type' at location 'path' into 'result'.

The path string works the same as in jansson_get.

Valid 'type' parameters are 'integer', 'real', 'string', 'object', 'array', 'true', 'false', and 'null' as well as abbreviated names such as 'int', 'str', and 'obj'. 'value' is ignored when type is 'true', 'false', or 'null'.

Note: If you want to insert a JSON-Integer value exceeding the C-Integer boundaries (e.g. C-type long), then the number can be provided as a string.

#### `jansson_set` usage

    ...
    # create a new json object and put a string in it at key "mystr"
    jansson_set("string", "mystr", "my input string", "$var(myjson)");
    # $var(myjson) =='{"mystr":"my input string"}'

    # add other values
    jansson_set("integer", "count", 9000, "$var(myjson)");
    jansson_set("true", "mybool", 0, "$var(myjson)");
    jansson_set("real", "pi", "3.14159", "$var(myjson)");
    # $var(myjson) == '{"mystr":"my input string", "count":9000, "mybool":true, "pi":3.14159}'

    # add a nested object
    jansson_set("obj", "myobj", '{"foo":"bar"}', "$var(myjson)");
    # $var(myjson) =='{"mystr":"my input string", "count":9000, "mybool":true, "pi":3.14159, "myobj":{"foo":"bar"}}'

    # change the nested object
    jansson_set("str", "myobj.foo", "baz", "$var(myjson)");
    # $var(myjson) == '{"mystr":"my input string", "count":9000, "mybool":true, "pi":3.14159, "myobj":{"foo":"baz"}}'
    ...

### `jansson_append(type, key/path, value, result)`

Like jansson_set but can be used to append to arrays. It can also be used to combine two json objects.

Note that when appending a json object to another json object, if there is a key that is shared between the two objects, that value will be overwritten by the new object.

#### `jansson_append` usage

    ...
    # create a new json array and append values to it
    $var(myarray) = '[]';
    jansson_append("int", "", 0, "$var(myarray)");
    jansson_append("int", "", 1, "$var(myarray)");
    jansson_append("int", "", 2, "$var(myarray)");
    jansson_append("int", "", 3, "$var(myarray)");
    jansson_append("int", "", 4, "$var(myarray)");
    # $var(myarray) == '[0,1,2,3,4]'

    # add that array to an object
    jansson_set("array", "list", $var(myarray), "$var(myjson)");
    # $var(myjson) == '{"list":[0,1,2,3,4]}'

    # append another value to the list
    jansson_append("int", "list", 5, "$var(myjson)");
    # $var(myjson) == '{"list":[0,1,2,3,4,5]}'

    # combining two json objects
    $var(newobj) = '{"b":2, "c":3}';
    jansson_append('obj', "", '{"a":1, "b":100}', "$var(newobj)");
    # $var(newobj) == '{"a":1,"b":100","c":3}';
    ...

### `jansson_array_size(key/path, src, dst)`

Puts the size of the array in 'src' at location 'path' into the pvar 'dst'.

This is particularly useful for looping through an array. See example.

#### `jansson_array_size` usage

    ...
    $var(array) = "{\"loopme\":[0,1,2,3,4,5]}";
    $var(count) = 0;
    jansson_array_size("loopme", $var(array), "$var(size)");
    while($var(count) < $var(size)) {
        jansson_get("loopme[$var(count)]", $var(array), "$var(v)");
        xlog("loopme[$var(count)] == $var(v)\n");
        $var(count) = $var(count) + 1;
    }
    ...

#### array concatenation

    ...
    $var(count) = 0;
    $var(appendme) = '[0,1]';
    $var(mylist) = '[2,3,4,5]';
    jansson_array_size("", $var(mylist), "$var(appendme_size)");
    while($var(count) < $var(appendme_size)) {
        jansson_get("[$var(count)]", $var(mylist), "$var(tmp)");
        jansson_append('int', "", $var(tmp), "$var(appendme)");
        $var(count) = $var(count) + 1;
    }
    ...

### `jansson_xdecode(json, xavp)`

Parse a JSON string in 'json' and store the elements in xapv 'xavp'. Top-level JSON must be an object or an array of objects. Nested arrays and objects are not decoded but stored as string.

#### `jansson_xdecode` usage

    ...
    jansson_xdecode('{"foo":"bar"}', "js");
    xlog("foo is $xavp(js=>foo)");
    ...

### `jansson_xencode(xavp, pv)`

Encode the items in the xavp 'xavp' as JSON and store the result in a pv. Nested xavp's are not supported.

#### `jansson_xencode` usage

    ...
    $xavp(a=>foo) = "bar";
    jansson_xencode("a", "$var(js)");
    # $var(js) = '{"foo":"bar"}'
    ...

### `jansson_get_field(field_name, src, dst)`

Copy the value of the field 'field_name' from json object 'src' and store it in pvar 'dst'. The field name is not evaluated as JSON path, therefore it has a different behaviour than jansson_get() and can be used when the field name contains path delimiters.

Note that till version 5.7.x, this function was similar to jansson_get(), after that its behaviour changed to work as described above. Also, the order of parameters changed.

#### `jansson_get_field` usage

    ...
    jansson_get_field("foo", "{'foo':'bar'}", "$var(foo)");
    xlog("foo is $var(foo)");
    jansson_get_field("foo.foz", "{'foo.foz':'bar.buz'}", "$var(foofoz)");
    xlog("foo.foz is $var(foofoz)");
    ...