Below is the driver interface that defines the driver names, the connect_parameters used by adding a datasource (see Section 10.1.3.1) and the driver methods.

struct ocrpt_input {
    const char **names;
    const ocrpt_input_connect_parameter **connect_parameters;
    bool (*connect)(ocrpt_datasource *ds,
                    const ocrpt_input_connect_parameter *params);
    ocrpt_query *(*query_add_sql)(ocrpt_datasource *ds,
                                  const char *name,
                                  const char *sql);
    ocrpt_query *(*query_add_file)(ocrpt_datasource *ds,
                                   const char *name,
                                   const char *filename,
                                   const int32_t *types,
                                   int32_t types_cols);
    ocrpt_query *(*query_add_data)(ocrpt_datasource *ds,
                                   const char *name,
                                   const void *data,
                                   int32_t rows,
                                   int32_t cols,
                                   const int32_t *types,
                                   int32_t types_cols);
    ocrpt_query *(*query_add_symbolic_data)(
                                   ocrpt_datasource *ds,
                                   const char *name,
                                   const char *dataname,
                                   int32_t rows,
                                   int32_t cols,
                                   const char *types,
                                   int32_t types_cols);
    void (*describe)(ocrpt_query *query,
                     ocrpt_query_result **result,
                     int32_t *result_cols);
    bool (*refresh)(ocrpt_query *query);
    void (*rewind)(ocrpt_query *query);
    bool (*next)(ocrpt_query *query);
    bool (*populate_result)(ocrpt_query *query);
    bool (*isdone)(ocrpt_query *query);
    void (*free)(ocrpt_query *query);
    bool (*set_encoding)(ocrpt_datasource *ds,
                         const char *encoding);
    void (*close)(const ocrpt_datasource *);
};
typedef struct ocrpt_input ocrpt_input;

The driver names is a NULL-terminated array of name strings. This allows the driver to be picked up using either name. For example the built-in MariaDB driver does so:

static const char *
ocrpt_mariadb_input_names[] = {
    "mariadb", "mysql", NULL
};

The connect_parameters data pointer and the connect method are either both set as valid, or both are NULL.

The query_add*() methods are optional. Some datasource drivers support direct or symbolic data, some support file formats, some are SQL based. A datasource input driver must support at least one of the interfaces.

The describe() method is mandatory. It returns an array of ocrpt_query_result data together with the number of columns in the result set. The result array must contain elements 3 times the number of columns in total due to the internal operation of OpenCReports.

#define OCRPT_EXPR_RESULTS (3)

The refresh() method is optional. See the PHP module source code for its potential uses.

The rewind(), next(), populate_result() and isdone() methods are all mandatory as they are required to traverse the result set.

The free() method is optional. It's needed if the query uses private data.

The set_encoding() method is optional. It's needed if the datasource input driver can use data in encodings other than UTF-8.

The close() method is optional. It's needed if the datasource connection uses private data.