Firebase - Download specific child (Swift 3) - ios

Question

I have attached a picture of my JSON tree
{
"-Ko4cg3ik5OFsnLTI4q4" : {
"FacebookPage" : {
"id" : "187736205061418",
"page" : "partyunlimitedtoronto"
},
"MapView" : {
"Edate" : 523940400,
"Sdate" : 523929600,
"intersted" : 3843,
"lat" : 45.510772273476,
"lng" : -73.563586483671,
"type" : "MUSIC",
"userID" : 1373802105986614,
"visibility" : "Public"
},
"address" : "Théâtre Corona",
"bio" : "evenko & Greenland Productions présentent\t\nMogwai\navec/with Xander Harris \nPortes: 19h00 - Spectacle: 20h00\n\nMise en vente: 24 mars à 10h\n\n37$ à 42$\n\nPrix lors de l’achat à la billetterie / Des frais de manutention peuvent s’appliquer lors de l’achat en ligne.\n\n.....................................................\n\nDoors: 7:00 pm - Show: 8:00 pm\n\nOn Sale: March 24 at 10am\n\n$37 to $42\n\nPrices for box office purchase / Handling fees may apply for online purchase.",
"name" : "Mogwai // Montréal",
"pic" : "https://scontent.xx.fbcdn.net/v/t1.0-9/17361785_10155183713782422_6829705267219994059_n.jpg?oh=150f6f53c74233b70b7f1b372c1db1e4&oe=59CF07EE",
"site" : "http://www.evenko.ca/fr/evenements/12392/mogwai/theatre-corona/12-06-2017",
"status" : "normal"
},
"-Ko4cgP2rXJCIRBODWpm" : {
"FacebookPage" : {
"id" : "620998508097068",
"page" : "partyunlimitedtoronto"
},
"MapView" : {
"Edate" : 43223454,
"Sdate" : 65837495,
"interested" : 2355,
"lat" : 45.3846583,
"lng" : -74.4736583,
"type" : "Party",
"userID" : 1373802105986614,
"visibility " : "Public"
},
"address" : "Théâtre Corona",
"bio" : "Greenland Productions & evenko présentent\t\t\t\t\t\t\nNazareth\t\t\t\navec/with Les Deuxluxes\t\n\nPortes: 19h00 - Spectacle: 20h00\n\nMise en vente: 14 avril à midi \n\n44,50$ à 48$\n\nPrix lors de l’achat à la billetterie / Des frais de manutention peuvent s’appliquer lors de l’achat en ligne.\n\n.....................................................\n\nDoors: 7:00 pm - Show: 8:00 pm\n\nOn Sale: April 14 at noon\n\n$44,50 to $48\n\nPrices for box office purchase / Handling fees may apply for online purchase.",
"name" : "Nazareth // Montréal",
"pic" : "https://scontent.xx.fbcdn.net/v/t1.0-9/17759677_10155255160737422_1735715699829358715_n.jpg?oh=1d6d1c250c2c6b38c6ef0de4483bd0a9&oe=5A0C4879",
"site" : "http://www.evenko.ca/fr/evenements/12489/nazareth/theatre-corona/08-03-2017",
"status" : "normal"
}
}
So I'm attempting to only download the "MapView" node inside every child when I run my program but in this case, I won't know the name of the parent of "MapView". Is there any way to only download a specific child like in this case. Otherwise, I was thinking whether I should use this style of structuring.
{
"EventView" : {
"-Ko4cg3ik5OFsnLTI4q4" : {
"FacebookPage" : {
"id" : "187736205061418",
"page" : "partyunlimitedtoronto"
},
"address" : "Théâtre Corona",
"bio" : "evenko & Greenland Productions présentent\t\nMogwai\navec/with Xander Harris \nPortes: 19h00 - Spectacle: 20h00\n\nMise en vente: 24 mars à 10h\n\n37$ à 42$\n\nPrix lors de l’achat à la billetterie / Des frais de manutention peuvent s’appliquer lors de l’achat en ligne.\n\n.....................................................\n\nDoors: 7:00 pm - Show: 8:00 pm\n\nOn Sale: March 24 at 10am\n\n$37 to $42\n\nPrices for box office purchase / Handling fees may apply for online purchase.",
"name" : "Mogwai // Montréal",
"pic" : "https://scontent.xx.fbcdn.net/v/t1.0-9/17361785_10155183713782422_6829705267219994059_n.jpg?oh=150f6f53c74233b70b7f1b372c1db1e4&oe=59CF07EE",
"site" : "http://www.evenko.ca/fr/evenements/12392/mogwai/theatre-corona/12-06-2017",
"status" : "normal"
},
"-Ko4cgP2rXJCIRBODWpm" : {
"FacebookPage" : {
"id" : "620998508097068",
"page" : "partyunlimitedtoronto"
},
"address" : "Théâtre Corona",
"bio" : "Greenland Productions & evenko présentent\t\t\t\t\t\t\nNazareth\t\t\t\navec/with Les Deuxluxes\t\n\nPortes: 19h00 - Spectacle: 20h00\n\nMise en vente: 14 avril à midi \n\n44,50$ à 48$\n\nPrix lors de l’achat à la billetterie / Des frais de manutention peuvent s’appliquer lors de l’achat en ligne.\n\n.....................................................\n\nDoors: 7:00 pm - Show: 8:00 pm\n\nOn Sale: April 14 at noon\n\n$44,50 to $48\n\nPrices for box office purchase / Handling fees may apply for online purchase.",
"name" : "Nazareth // Montréal",
"pic" : "https://scontent.xx.fbcdn.net/v/t1.0-9/17759677_10155255160737422_1735715699829358715_n.jpg?oh=1d6d1c250c2c6b38c6ef0de4483bd0a9&oe=5A0C4879",
"site" : "http://www.evenko.ca/fr/evenements/12489/nazareth/theatre-corona/08-03-2017",
"status" : "normal"
}
},
"MapView" : {
"-Ko4cg3ik5OFsnLTI4q4" : {
"Edate" : 534312000,
"Sdate" : 534301200,
"intersted" : 652,
"lat" : 45.4827983,
"lng" : -73.575107687761,
"type" : "MUSIC",
"userID" : "1373802105986614",
"visibility" : "Public"
},
"-Ko4cgP2rXJCIRBODWpm" : {
"Edate" : 523508400,
"Sdate" : 523497600,
"intersted" : 382,
"lat" : 45.4827983,
"lng" : -73.575107687761,
"type" : "MUSIC",
"userID" : "1373802105986614",
"visibility" : "Public"
}
}
}
where in this case I would have the information in a separate child but where there are parent nodes with the same name in both EventView and MapView.

Answer 1

For the First structure
This structure will definitely make our query download the whole EventView node
var AllMapViews = []; //<-- array of all mapview objects
var path = "/EventView";
firebase.database().ref(path)
.once("value")
.then(eventViews => {
eventViews.forEach(thisevent => {
AllMapViews.push(thisevent.val().MapView);
})
});
Hence the result of the above will look like this
AllMapViews = [
{ "EventDate":343,"Sdate" : 65837495 ..},
{ "EventDate":343,"Sdate" : 65837495 ..},
{ "EventDate":343,"Sdate" : 65837495 ..},
...
]
For the Second structure (My Choice)
This structure will allow our query download only MapViews for all EventViews. Hence, making it the structure of choice in your implementation. Though it will need you to monitor the main EventView nodes often to know when the main event is deleted so that you can also delete it's corresponding MapView.
var AllMapViews = []; //<-- array of all mapview objects
var path = "/MapViews";
firebase.database().ref(path)
.once("value")
.then(mapViews => {
mapViews.forEach(map => {
AllMapViews.push(map.val());
})
});
Hence the result of the above will look like this
AllMapViews = [
{ "EventDate":343,"Sdate" : 65837495 ..},
{ "EventDate":343,"Sdate" : 65837495 ..},
{ "EventDate":343,"Sdate" : 65837495 ..},
...
]