Change the type of a MongoDB field to integer from its console

In the C/C++ "sense of the word", ints are not actually guaranteed to be 32-bit values. An int must be at least 16-bits, but generally matches the platform architecture (eg. 32 or 64bit).

As mentioned by @Jasd, JavaScript does only have one numeric type which is a floating point (double in C).

From the MongoDB shell you should be able to use the functions NumberInt(..) to get a BSON 32-bit integer value or NumberLong(..) to get a BSON 64-bit integer.

You can fix the types of all values for a certain field on the console with something like:

db.Statistic.find({kodoId: {$exists: true}}).forEach(function (x) {  x.kodoId = NumberInt(x.kodoId);  db.Statistic.save(x);});

This will only load documents that have the kodoId field and convert them to int and resave. You could do something like:

db.Statistic.find({kodoId: {$exists: true}}, {kodoId: 1}).forEach(function (x) {   db.Statistic.update({ _id: x._id },      {$set: {        kodoId: NumberInt(x.kodoId)      }});});

with a second param which will only load the kodoId value (hopefully from an index). This should be much quicker since it doesn't need to load and resave the entire document - just that one field.

MongoDB's shell is powered by a JavaScript Engine. And JavaScript has no type for integer. It knows only Number, which is a type for floating-point numbers.
You can try using the MongoDB type NumberLong, but it didn't work out for me when i once had the same problem.