Question

today my map function started reporting assertion failure 13076 ‘recursive toObject’ code. It worked just fine yesterday.

Here’s my map function:

function () {
    for(i=0; i<this.values.length; i++) {
        emit(this.values[i].id, {
            'id': this.values[i].id,
            'start_date': this.values[i].start_date,
            'end_date': this.values[i].end_date,
            'hash': this.values[i].hash,
            'url': this.values[i].url});
    }  
}

I have tried replacing for loop with forEach function, but result is the same.

What is interesting function with scope variable limiting map function to single emit works just fine:

function () {
    for(i=0; i<this.values.length; i++) {
        if(this.values[i].id == myId) {
            emit(this.values[i].id, {
                'id': this.values[i].id,
                'start_date': this.values[i].start_date,
                'end_date': this.values[i].end_date,
                'hash': this.values[i].hash,
                'url': this.values[i].url});
        }
    }
}

I can, of course, perform this mapping directly in code, but I wouldn’t want to encounter this error some other time when I really need to use MapReduce.

Answer 1

Ok, so the error message was really vague, but the problem seems to be caused by duplicate value of the ‘id’ field in ‘values’ array. When I changed the id in one of the array elements the function started working again.