Table of Contents
List of Examples
jansson_get usagejansson_set usagejansson_append usagejansson_array_size usagejansson_get_field usageTable of Contents
This module provides operations on JSON strings using JANSSON library. It has support for JSON-PATH operations.
Copy the value at the location 'path' from the json object 'src' and store it in pvar 'dst'.
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 key/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.
Example 1.1. 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 $var(n)");
...
Insert 'value' as 'type' at location 'path' into 'result'.
The path string works the same as in jansson_get.
Valid 'type' parameters are 'integer', 'real', 'string', 'object', 'array', 'true', 'false', and 'null' as well as abbriviated names such as 'int', 'str', and 'obj'. 'value' is ignored when type is 'true', 'false', or 'null'.
Note: If you want to insert a JSON-Integer value exceeding the C-Integer boundaries (e.g. C-type long), the a the number can be provided as a string.
Example 1.2. jansson_set usage
...
# create a new json object and put a string in it at key "mystr"
jansson_set("string", "mystr", "my input string", "$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"}}'
...
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.
Example 1.3. 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}';
...
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.
Example 1.4. 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;
}
...
Example 1.5. array concatination
...
$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) = $var(count) + 1;
}
...
Copy field 'field_name' from json object 'src' and store it in pvar 'dst'.
This function is deprecated but kept for backwards compatibility. Right now it is just a wrapper around jansson_get, and its functionality is the same.
Example 1.6. jansson_get_field usage
...
jansson_get_field("{'foo':'bar'}", "foo", "$var(foo)");
xlog("foo is $var(foo)");
...