Is there a character limit for the string parameter used in the startAt() function of

Question

Is there a character limit for the string parameter used in the startAt() function of

I was just about to post this question on their github repository, but it looks like they prefer general inquiries to be asked here instead.

Is there a character limit for parameters when using startAt() to retrieve data from the firebase database?

I recently encountered an issue where it appears to be restricted to only 41 characters, but I haven't been able to find any documentation confirming this.

If indeed there is a limit, is there a way to extend it? (I need to filter values with up to 60 characters)

Although I can pass longer parameters, the database seems to only filter results based on the first 41 characters and ignores the rest of the value.

Just to note, I am using the JavaScript SDK in this case.

The dataset consists of values that are approximately 100 characters long, with the first 41 characters being identical in each one, differing at the tail end:

{
  "obj1": {"param": "abcdefghijklmnopqrstuvwxyz0123456789ABCDEF_0123456789ABCDEFabcdefghijklmnopqrstuvwxyz0123456789ABCDEF"},
  "obj2": {"param": "abcdefghijklmnopqrstuvwxyz0123456789ABCDEF_123456789ABCDEFabcdefghijklmnopqrstuvwxyz0123456789ABCDEF"},
  "obj3": {"param": "abcdefghijklmnopqrstuvwxyz0123456789ABCDEF_23456789ABCDEFabcdefghijklmnopqrstuvwxyz0123456789ABCDEF"},
  "obj4": {"param": "abcdefghijklmnopqrstuvwxyz0123456789ABCDEF_3456789ABCDEFabcdefghijklmnopqrstuvwxyz0123456789ABCDEF"},
  "obj5": {"param": "abcdefghijklmnopqrstuvwxyz0123456789ABCDEF_456789ABCDEFabcdefghijklmnopqrstuvwxyz0123456789ABCDEF"}
}

Currently, I need to retrieve "obj1" based on the value of the key "param," knowing only the first 60 characters of it (thus unable to use equalTo()):

var ref = firebase.database().ref("/some/data");

ref.orderByChild("param")
   .startAt("abcdefghijklmnopqrstuvwxyz0123456789ABCDEF_0123456789ABCDEFabc") <- this length is 60 characters
   .once("value")
   .then(function(snapshot) {
     snapshot.forEach(function(child) {
       console.log(child.key);
     });
   })

My expectation was to receive only one result, but the code above returns all records from the set instead.

javascript firebase firebase-realtime-database

Answer 1

Answer №1

It appears that there may be some confusion regarding the functionality of the startAt operation. It seems like you are attempting to filter strings that begin with a specific substring using startAt, but that is not how this function operates.

When you organize the children based on the value of the param property, Firebase arranges all children according to that parameter's value. Then, when you start at

abcdefghijklmnopqrstuvwxyz0123456789ABCDEF_0123456789ABCDEFabc

, it starts retrieving nodes from that point onward. In this scenario,

abcdefghijklmnopqrstuvwxyz0123456789ABCDEF_123456789ABCDEFabcdefghijklmnopqrstuvwxyz0123456789ABCDEF

comes after

abcdefghijklmnopqrstuvwxyz0123456789ABCDEF_0123456789ABCDEFabc

.

If you desire to retrieve the first child starting at a specific value, consider utilizing

.startAt(searchTerm).limitToFirst(1)

.

To obtain children starting with a particular value, employ a closed range with

startAt(searchTerm).endAt(searchTerm+"\uf8ff")

. The character \uf8ff represents the final Unicode character in this context.

Answer 2

It appears that there may be some confusion regarding the functionality of the startAt operation. It seems like you are attempting to filter strings that begin with a specific substring using startAt, but that is not how this function operates.

When you organize the children based on the value of the param property, Firebase arranges all children according to that parameter's value. Then, when you start at

abcdefghijklmnopqrstuvwxyz0123456789ABCDEF_0123456789ABCDEFabc

, it starts retrieving nodes from that point onward. In this scenario,

abcdefghijklmnopqrstuvwxyz0123456789ABCDEF_123456789ABCDEFabcdefghijklmnopqrstuvwxyz0123456789ABCDEF

comes after

abcdefghijklmnopqrstuvwxyz0123456789ABCDEF_0123456789ABCDEFabc

.

If you desire to retrieve the first child starting at a specific value, consider utilizing

.startAt(searchTerm).limitToFirst(1)

.

To obtain children starting with a particular value, employ a closed range with

startAt(searchTerm).endAt(searchTerm+"\uf8ff")

. The character \uf8ff represents the final Unicode character in this context.

Answer 3

Answer №2

I attempted to replicate this issue in both a JavaScript and Swift project, but was unsuccessful.

Here is the data I used:

{
  "key1" : "abcdefghijklmnopqrstuvwxyz0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789",
  "key2" : "abcdefghijklmnopqrstuvwxyz0123456789ABCDEFZHIJKLMNOPQRSTUVWXYZ0123456789",
  "key3" : "abcdefghijklmnopqrstuvwxyz0123456789ABCDEFHHIJKLMNOPQRSTUVWXYZ0123456789",
  "key4" : "abcdefghijklmnopqrstuvwxyz0123456789ABCDEFIHIJKLMNOPQRSTUVWXYZ0123456789",
  "key5" : "abcdefghijklmnopqrstuvwxyz0123456789ABCDEFJHIJKLMNOPQRSTUVWXYZ0123456789"
}

This is my JavaScript code:

var ref = firebase.database().ref("/51151783");

ref.orderByValue()
   .startAt("abcdefghijklmnopqrstuvwxyz0123456789ABCDEFI")
   .once("value")
   .then(function(snapshot) {
     snapshot.forEach(function(child) {
       console.log(child.key);
     });
   })

And here is my Swift code:

func searchForLongValue51151783() {
    let ref = Database.database().reference(withPath: "51151783")
    ref.queryOrderedByValue().queryStarting(atValue: "abcdefghijklmnopqrstuvwxyz0123456789ABCDEFI").observeSingleEvent(of: .value, with: { (snapshot) in
            for child in snapshot.children {
                print((child as! DataSnapshot).key)
            }
    })
}

The result of the queries are:

key4

key5

key2

You can view the demonstration on jsbin: http://jsbin.com/lupebuwihu/edit?js,console.

Answer 4

I attempted to replicate this issue in both a JavaScript and Swift project, but was unsuccessful.

Here is the data I used:

{
  "key1" : "abcdefghijklmnopqrstuvwxyz0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789",
  "key2" : "abcdefghijklmnopqrstuvwxyz0123456789ABCDEFZHIJKLMNOPQRSTUVWXYZ0123456789",
  "key3" : "abcdefghijklmnopqrstuvwxyz0123456789ABCDEFHHIJKLMNOPQRSTUVWXYZ0123456789",
  "key4" : "abcdefghijklmnopqrstuvwxyz0123456789ABCDEFIHIJKLMNOPQRSTUVWXYZ0123456789",
  "key5" : "abcdefghijklmnopqrstuvwxyz0123456789ABCDEFJHIJKLMNOPQRSTUVWXYZ0123456789"
}

This is my JavaScript code:

var ref = firebase.database().ref("/51151783");

ref.orderByValue()
   .startAt("abcdefghijklmnopqrstuvwxyz0123456789ABCDEFI")
   .once("value")
   .then(function(snapshot) {
     snapshot.forEach(function(child) {
       console.log(child.key);
     });
   })

And here is my Swift code:

func searchForLongValue51151783() {
    let ref = Database.database().reference(withPath: "51151783")
    ref.queryOrderedByValue().queryStarting(atValue: "abcdefghijklmnopqrstuvwxyz0123456789ABCDEFI").observeSingleEvent(of: .value, with: { (snapshot) in
            for child in snapshot.children {
                print((child as! DataSnapshot).key)
            }
    })
}

The result of the queries are:

key4

key5

key2

You can view the demonstration on jsbin: http://jsbin.com/lupebuwihu/edit?js,console.

Is there a character limit for the string parameter used in the startAt() function of

Answer №1

Answer №2

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