Features
--------
* Full JSON support
* Lightweight (only 2 files)
* Simple API
* Addressing json values with dot notation
* C89 compatible
* Test suites
Installation
------------
Extract source.lha and copy parson.h and parson.c to you source code tree.
Pre-compiled executable for test is included: test and testcpp. Please
be aware they both contain bugs in double precision parsing - tracing back
to linked version of clib2.
Parsing JSON
------------
Here is a function, which prints basic commit info (date, sha and author)
from a github repository (pre-compiled version in samples/parse).
void print_commits_info(const char *username, const char *repo) {
JSON_Value *root_value;
JSON_Array *commits;
JSON_Object *commit;
size_t i;
char curl_command[512];
char cleanup_command[256];
char output_filename[] = "commits.json";
/* it ain't pretty, but it's not a libcurl tutorial */
sprintf(curl_command,
"curl -s \"https://api.github.com/repos/%s/%s/commits\" > %s",
username, repo, output_filename);
sprintf(cleanup_command, "rm -f %s", output_filename);
system(curl_command);
/* parsing json and validating output */
root_value = json_parse_file(output_filename);
if (json_value_get_type(root_value) != JSONArray) {
system(cleanup_command);
return;
}
/* getting array from root value and printing commit info */
commits = json_value_get_array(root_value);
printf("%-10.10s %-10.10s %s\n", "Date", "SHA", "Author");
for (i = 0; i < json_array_get_count(commits); i++) {
commit = json_array_get_object(commits, i);
printf("%.10s %.10s %s\n",
json_object_dotget_string(commit, "commit.author.date"),
json_object_get_string(commit, "sha"),
json_object_dotget_string(commit, "commit.author.name"));
}
/* cleanup code */
json_value_free(root_value);
system(cleanup_command);
}
Calling print_commits_info("torvalds", "linux"); prints:
Date SHA Author
2012-10-15 dd8e8c4a2c David Rientjes
2012-10-15 3ce9e53e78 Michal Marek
2012-10-14 29bb4cc5e0 Randy Dunlap
2012-10-15 325adeb55e Ralf Baechle
2012-10-14 68687c842c Russell King
2012-10-14 ddffeb8c4d Linus Torvalds
...
Persistence
-----------
In this example I'm using parson to save user information to a file and then
load it and validate later (pre-compiled version in samples/persistence).
void persistence_example(void) {
JSON_Value *schema = json_parse_string("{\"name\":\"\"}");
JSON_Value *user_data = json_parse_file("user_data.json");
char buf[256];
const char *name = NULL;
if (user_data == NULL || json_validate(schema, user_data) != JSONSuccess)
{
puts("Enter your name:");
scanf("%s", buf);
user_data = json_value_init_object();
json_object_set_string(json_object(user_data), "name", buf);
json_serialize_to_file(user_data, "user_data.json");
}
name = json_object_get_string(json_object(user_data), "name");
printf("Hello, %s.", name);
json_value_free(schema);
json_value_free(user_data);
return;
}
Serialization
-------------
Creating JSON values is very simple thanks to the dot notation.
Object hierarchy is automatically created when addressing specific
fields. In the following example I create a simple JSON value
containing basic information about a person (pre-compiled version
in samples/serialization).
void serialization_example(void) {
JSON_Value *root_value = json_value_init_object();
JSON_Object *root_object = json_value_get_object(root_value);
char *serialized_string = NULL;
json_object_set_string(root_object, "name", "John Smith");
json_object_set_number(root_object, "age", 25);
json_object_dotset_string(root_object, "address.city", "Cupertino");
json_object_dotset_value(root_object, "contact.emails",
json_parse_string("[\"email@example.com\",\"email2@example.com\"]"));
serialized_string = json_serialize_to_string_pretty(root_value);
puts(serialized_string);
json_free_serialized_string(serialized_string);
json_value_free(root_value);
}
Output:
{
"name": "John Smith",
"age": 25,
"address": {
"city": "Cupertino"
},
"contact": {
"emails": [
"email@example.com",
"email2@example.com"
]
}
}
Contributing
------------
The author claims to always merge working bug fixes. However, if you want
to add something new to the API, please create an "issue" on github for
this first so you can discuss if it should end up in the library before you
start implementing it. Remember to follow parson's code style and
write appropriate tests.
License
-------
The MIT License (MIT)
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