why can't I add to my linked list in my hash table if it's already full in C?

Question

when I'm adding to a NULL bucket in a hashTable, my function works very well, but it doesn't when there is already a value in that bucket, and I can't find the problem here !?

void myHashSetAdd(MyHashSet* obj, int key) {
  int bucket=key%10;
  ListNode* test=obj->t[bucket],*a;
  if(!test){    // if bucket is empty ( works well )
    obj->t[bucket]=node(key);
  } else {   // if it's full ( here is the problem ) 
    a=node(key);
    a->next=test;   // assign it as the head of the linked list
    obj->t[bucket]=a;
  }
}

Here is My hashTable fucntions:

typedef struct {
  int val;
  struct ListNode *next;
}ListNode;

typedef struct {
    ListNode *t[10];
} MyHashSet;

ListNode *node(int val){   
  ListNode *temp=malloc(sizeof(ListNode));
  temp->val=val,temp->next=0;
  return temp;
}


MyHashSet* myHashSetCreate() {
    MyHashSet *hashTable=malloc(sizeof(MyHashSet));
    for(int i=0;i<10;i++){hashTable->t[i]=0;} // all buckets to NULL;
    return hashTable;
}

Answer 1

You can achieve this using hasManyThrough relationship. After defining relationship you can count simply using count() on relationship.