Mongo DB

# command line
mongoimport -u "root" -p "<password>" --authenticationDatabase "admin" [--jsonArray] --db <schema> --collection <collection> --file <filename>

# command line
mongoexport -u "root" --authenticationDatabase "admin" -d <schema> -c <collection> -o <filename>

/* robo3t syntax */
db.getCollection('collection-name').find({ 'field-name': { $size: 2 } });
db.getCollection('sa-access-points').count({ 'field-name': { $size: 2 } };

/* robo3t syntax - update all values of the field "b" to value "c" in the collection "a" */
db.getCollection('a').updateMany({ }, {
  $set: {
    "b": 'c'
  }
});
/* if you would like to update all the element called propertyToUpdate  of a subarray */
db.getCollection("a").updateMany({
  // other filters
  "subarray": {$type: "array"} //make sure that the element is an array
 }, {
  $set: {
    "subarray.$[].propertyToUpdate": "value"
  },
});

/* mongoose syntax - complex update */
await this.database.connection.db.collection("collection-name").updateMany({
    "obj1.prop1": {    //obj1: [{prop1: "val", prop2: "abc"}, {prop1: "val", prop2: "dsa"}]
        $in: "val"
    },  //and
    "obj1.prop2": 'abc'    //exact match
}, {
    $set: {
        "obj1.$.prop2": 'bcd'   //result obj1: [{prop1: "val", prop2: "bcd"}, {prop1: "val", prop2: "dsa"}]
    }
});

/* mongoose syntax - get all elements of a collection and replace it */
/* use it only for small amount of elems */
let elems = await this.database.connection.db.collection("collection").find({}).toArray();
for (let ele of elems) {
    /* manipulate the object... */
    await this.database.connection.db.collection('collection').replaceOne({ _id: ele._id }, ele);
}