ONQL C Driver

Official C client library for the ONQL database server.

Installation

The C driver is not currently published to a binary package registry; install it from source. Each tagged release also attaches prebuilt archives to its GitHub Release page.

Build from source

git clone https://github.com/ONQL/onqlclient-c.git
cd onqlclient-c
mkdir build && cd build
cmake ..
make
sudo make install

CMake FetchContent

include(FetchContent)
FetchContent_Declare(
    onql
    GIT_REPOSITORY https://github.com/ONQL/onqlclient-c.git
    GIT_TAG        v0.1.0
)
FetchContent_MakeAvailable(onql)

target_link_libraries(your_target PRIVATE onql)

Quick Start

#include <stdio.h>
#include "onql.h"

int main(void) {
    onql_client *c = onql_connect("localhost", 5656);
    if (!c) return 1;

    char *err = NULL;

    char *data = onql_insert(c, "mydb", "users",
        "{\"id\":\"u1\",\"name\":\"John\",\"age\":30}", &err);
    onql_free_string(data);
    onql_free_string(err);

    char *q = onql_build("mydb.users[id=$1].id",
                         (const char*[]){"u1"},
                         (const int[]){1}, 1);

    err = NULL;
    data = onql_update(c, "mydb", "users", "{\"age\":31}",
                       q, NULL, NULL, &err);
    onql_free_string(data);
    onql_free_string(err);
    onql_free_string(q);

    onql_delete(c, "mydb", "users", "", NULL, "[\"u1\"]", &err);

    onql_close(c);
    return 0;
}

API Reference

Connection

onql_client *onql_connect(const char *host, int port);
void onql_close(onql_client *client);

Raw request

onql_response *onql_send_request(onql_client *client,
                                 const char *keyword,
                                 const char *payload);
void onql_response_free(onql_response *res);

Response Structure

typedef struct {
    char *request_id;
    char *source;
    char *payload;
} onql_response;

Direct ORM-style API

On top of raw onql_send_request, the driver exposes convenience helpers for the insert / update / delete / onql operations. Each helper builds the standard payload envelope, parses the {error, data} response, and returns the decoded data as a newly heap-allocated string (free with onql_free_string()).

Because the driver is dependency-free, every JSON-valued parameter is passed as a pre-serialized JSON string — use cJSON, jansson, or similar.

db is passed explicitly to insert / update / delete. onql takes a fully-qualified ONQL expression.

query arguments are ONQL expression strings, e.g. mydb.users[id="u1"].id.

Error handling

Every helper accepts an out_error out-parameter. If the server returned a non-empty error, the helper returns NULL and *out_error is set to a newly allocated error string. On transport failure, both are NULL.

onql_insert

char *onql_insert(onql_client *client,
                  const char *db,
                  const char *table,
                  const char *record_json,   /* a single JSON object */
                  char **out_error);

onql_update

char *onql_update(onql_client *client,
                  const char *db,
                  const char *table,
                  const char *record_json,
                  const char *query,         /* ONQL expression, or "" */
                  const char *protopass,     /* NULL -> "default" */
                  const char *ids_json,      /* NULL -> "[]" */
                  char **out_error);

onql_delete

char *onql_delete(onql_client *client,
                  const char *db,
                  const char *table,
                  const char *query,
                  const char *protopass,
                  const char *ids_json,
                  char **out_error);

onql_onql

char *onql_onql(onql_client *client,
                const char *query,
                const char *protopass,       /* NULL -> "default" */
                const char *ctxkey,          /* NULL -> ""        */
                const char *ctxvalues_json,  /* NULL -> "[]"      */
                char **out_error);

onql_build

char *onql_build(const char *query,
                 const char *const *values,
                 const int *is_string,
                 int n_values);

Replace $1, $2, … placeholders. If is_string[i] is non-zero the value is double-quoted when substituted; otherwise inlined verbatim.

onql_process_result

int onql_process_result(const char *raw, char **out_data, char **out_error);

onql_free_string

void onql_free_string(char *s);

Protocol

<request_id>\x1E<keyword>\x1E<payload>\x04

• \x1E — field delimiter
• \x04 — end-of-message marker

License

MIT