Method: Oj::Doc.open_file

Defined in:
ext/oj/fast.c

.open_file(filename) ⇒ Object

Parses a JSON document from a file and then yields to the provided block if one is given with an instance of the Oj::Doc as the single yield parameter. If a block is not given then an Oj::Doc instance is returned and must be closed with a call to the #close() method when no longer needed.

@param [String] filename name of file that contains a JSON document

method call

Examples:

File.open('array.json', 'w') { |f| f.write('[1,2,3]') }
Oj::Doc.open_file(filename) { |doc| doc.size() }  #=> 4
# or as an alternative
doc = Oj::Doc.open_file(filename)
doc.size()  #=> 4
doc.close()

Yield Parameters:

  • doc (Oj::Doc) —

    parsed JSON document

Yield Returns:

  • (Object) —

    returns the result of the yield as the result of the



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# File 'ext/oj/fast.c', line 1122

static VALUE doc_open_file(VALUE clas, VALUE filename) {
    char          *path;
    char          *json;
    FILE          *f;
    size_t         len;
    volatile VALUE obj;
    int            given = rb_block_given_p();

    path = StringValuePtr(filename);
    if (0 == (f = fopen(path, "r"))) {
        rb_raise(rb_eIOError, "%s", strerror(errno));
    }
    fseek(f, 0, SEEK_END);
    len  = ftell(f);
    json = OJ_R_ALLOC_N(char, len + 1);

    fseek(f, 0, SEEK_SET);
    if (len != fread(json, 1, len, f)) {
        fclose(f);
        rb_raise(rb_const_get_at(Oj, rb_intern("LoadError")),
                 "Failed to read %lu bytes from %s.",
                 (unsigned long)len,
                 path);
    }
    fclose(f);
    json[len] = '\0';
    obj       = parse_json(clas, json, given);
    // TBD is this needed
    /*
    if (given) {
        OJ_R_FREE(json);
    }
    */
    return obj;
}