C cannot retrieve mongodb BSON array

Question

I meet a problem on C program connect to mongodb to retrieve document...I dont know how to solve it, please help...

The record structure :

{ "District" : "HK", 
  "Contact": [ {"name":"Person A","telephone":"1111-1111"} ,   
               {"name":"Person B", "telephone":"2222-2222}  ] 
}

Here is my code:

while( mongo_cursor_next( cursor ) == MONGO_OK ){
    bson_iterator iterator[1];
    //print district
    if ( bson_find( iterator, mongo_cursor_bson( cursor ), "District" )) {  
        printf( "District: %s\n", bson_iterator_string( iterator ) );  

    //print array elements
    if ( bson_find( iterator, mongo_cursor_bson( cursor ), "Contact" )) {
        bson_iterator subit[1];
        bson_iterator_subiterator(iterator, subit);

        //get array list element one by one
        while(bson_iterator_more(subit)){
            if(bson_iterator_next(subit)!=BSON_EOO){
                bson sub_Object[1];
                bson_iterator_subobject_init(subit, sub_Object,1);
                //bson_print(sub_Object);

                //comment out the following bson_find could show the expected result
                if(bson_find(subit, sub_Object, "name"))
                    printf("\tName : %s\n", bson_iterator_string(subit));
                if(bson_find(subit, sub_Object, "telephone"))
                    printf("\tTelephone: %s\n", bson_iterator_string(subit));

                bson_destroy(sub_Object);
            }
        }
   }

}

Output

District: HK
Name: Person A
Telephone: 1111-1111

Any one know why Person B record disappear??

I have test if DO NOT use bson_find inside the second while loop, it could able to print out all the element by bson_print!!

Is there a bug on mongodb ?? Or my code is wrong?

Thank you very much!!!

Man Programmer · Accepted Answer · 2013-09-24 05:43:51Z

1

Create new iterator

 bson_iterator nInterat[1];

below subit iterator

bson_iterator subit[1];
bson_iterator nInterat[1];

instead of this

bson_iterator_subobject_init(subit, sub_Object,1)

change like

bson_iterator_subobject_init(nInterat, sub_Object,1)

if(bson_find(nInterat, sub_Object, "name"))
    printf("\tName : %s\n", bson_iterator_string(nInterat));
if(bson_find(nInterat, sub_Object, "telephone"))
    printf("\tTelephone: %s\n", bson_iterator_string(nInterat));

because your subit iterator is overwrite with current sub_object Index

answered Sep 24, 2013 at 5:43

Man Programmer

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