.\" This manpage is Copyright (C) 2016 MongoDB, Inc.
.\" 
.\" Permission is granted to copy, distribute and/or modify this document
.\" under the terms of the GNU Free Documentation License, Version 1.3
.\" or any later version published by the Free Software Foundation;
.\" with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts.
.\" A copy of the license is included in the section entitled "GNU
.\" Free Documentation License".
.\" 
.TH "JSON" "3" "2016\(hy10\(hy12" "libbson"
.SH NAME
JSON \- None
.SH "CONVERTING BSON TO JSON"


There are often times where you might want to convert a BSON document to JSON. It is convenient for debugging as well as an interchange format. To help with this, Libbson contains the function
.B bson_as_json(3)
.

.SH "CONVERT TO JSON"

.nf
bson_t *b;
size_t len;
char *str;

b = BCON_NEW ("a", BCON_INT32 (1));

str = bson_as_json (b, &len);
printf ("%s\en", str);
bson_free (str);

bson_destroy (b);
.fi

.B { "a" : 1 }


.SH "CONVERTING JSON TO BSON"


Converting back from JSON is also useful and common enough that we added
.B bson_init_from_json(3)
and
.B bson_new_from_json(3)
.

The following example creates a new
.B bson_t
from the JSON string
.B {"a":1}
.

.SH "CONVERT FROM JSON"

.nf
bson_t *b;
bson_error_t error;

b = bson_new_from_json ("{\e"a\e":1}", \(hy1, &error);

if (!b) {
   printf ("Error: %s\en", error.message);
} else {
   bson_destroy (b);
}
.fi


.SH "STREAMING JSON PARSING"


Libbson provides
.B bson_json_reader_t
to allow for parsing a sequence of JSON documents into BSON. The interface is similar to
.B bson_reader_t
but expects the input to be in the
.B MongoDB extended JSON
format.

.SH "JSON-TO-BSON.C"

.nf

/*
 * Copyright 2013 MongoDB, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE\(hy2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */


/*
 * This program will print each JSON document contained in the provided files
 * as a BSON string to STDOUT.
 */


#include <bson.h>
#include <stdlib.h>
#include <stdio.h>


int
main (int   argc,
      char *argv[])
{
   bson_json_reader_t *reader;
   bson_error_t error;
   const char *filename;
   bson_t doc = BSON_INITIALIZER;
   int i;
   int b;

   /*
    * Print program usage if no arguments are provided.
    */
   if (argc == 1) {
      fprintf (stderr, "usage: %s FILE...\en", argv[0]);
      return 1;
   }

   /*
    * Process command line arguments expecting each to be a filename.
    */
   for (i = 1; i < argc; i++) {
      filename = argv[i];

      /*
       * Open the filename provided in command line arguments.
       */
      if (0 == strcmp (filename, "\(hy")) {
         reader = bson_json_reader_new_from_fd (STDIN_FILENO, false);
      } else {
         if (!(reader = bson_json_reader_new_from_file (filename, &error))) {
            fprintf (stderr, "Failed to open \e"%s\e": %s\en",
                     filename, error.message);
            continue;
         }
      }

      /*
       * Convert each incoming document to BSON and print to stdout.
       */
      while ((b = bson_json_reader_read (reader, &doc, &error))) {
         if (b < 0) {
            fprintf (stderr, "Error in json parsing:\en%s\en", error.message);
            abort ();
         }

         if (fwrite (bson_get_data(&doc), 1, doc.len, stdout) != doc.len) {
            fprintf (stderr, "Failed to write to stdout, exiting.\en");
            exit (1);
         }
         bson_reinit (&doc);
      }

      bson_json_reader_destroy (reader);
      bson_destroy (&doc);
   }

   return 0;
}
.fi


.SH "EXAMPLES"

The following example reads BSON documents from
.B stdin
and prints them to
.B stdout
as JSON.

.SH "BSON-TO-JSON.C"

.nf

/*
 * Copyright 2013 MongoDB, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE\(hy2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */


/*
 * This program will print each BSON document contained in the provided files
 * as a JSON string to STDOUT.
 */


#include <bson.h>
#include <stdio.h>


int
main (int   argc,
      char *argv[])
{
   bson_reader_t *reader;
   const bson_t *b;
   bson_error_t error;
   const char *filename;
   char *str;
   int i;

   /*
    * Print program usage if no arguments are provided.
    */
   if (argc == 1) {
      fprintf(stderr,
              "usage: %s [FILE | \(hy]...\enUse \(hy for STDIN.\en",
              argv[0]);
      return 1;
   }

   /*
    * Process command line arguments expecting each to be a filename.
    */
   for (i = 1; i < argc; i++) {
      filename = argv[i];

      if (strcmp (filename, "\(hy") == 0) {
         reader = bson_reader_new_from_fd (STDIN_FILENO, false);
      } else {
         if (!(reader = bson_reader_new_from_file (filename, &error))) {
            fprintf (stderr, "Failed to open \e"%s\e": %s\en",
                     filename, error.message);
            continue;
         }
      }

      /*
       * Convert each incoming document to JSON and print to stdout.
       */
      while ((b = bson_reader_read (reader, NULL))) {
         str = bson_as_json(b, NULL);
         fprintf(stdout, "%s\en", str);
         bson_free(str);
      }

      /*
       * Cleanup after our reader, which closes the file descriptor.
       */
      bson_reader_destroy (reader);
   }

   return 0;
}
.fi



.B
.SH COLOPHON
This page is part of libbson.
Please report any bugs at https://jira.mongodb.org/browse/CDRIVER.