Firebase checking value if its null
im working on a simple coding here but i kind of stuck.
basicly the code will check if the username exists or not, so im using these codes;
Data Structure;
"usernametouid": {
"username": "userid",
}
Codes;
this.afDatabase.object(`usernametouid/${this.username}`).subscribe(data => {
const dtvl = data.$value;
if(dtvl != null) {
console.log("username exists")
} else if(dtvl == null) {
console.log("good to go")
this.createProfile();
}
on createProfile function that gets a uid so value being no longer null.
Actually its working allright if username already exist part, but if its not, for a little moment (i assume during retrieving data ) it getting not-null again.
So output being like this (if type a null username):
good to go
username exists
i dont understand why its giving me "username exists" again ? what would be the solution or any better way.
thanks for your assist..
javascript angular firebase ionic-framework
asked Nov 20 '18 at 15:36
ugrdursunugrdursun
2418
add a comment |
im working on a simple coding here but i kind of stuck.
basicly the code will check if the username exists or not, so im using these codes;
Data Structure;
"usernametouid": {
"username": "userid",
}
Codes;
this.afDatabase.object(`usernametouid/${this.username}`).subscribe(data => {
const dtvl = data.$value;
if(dtvl != null) {
console.log("username exists")
} else if(dtvl == null) {
console.log("good to go")
this.createProfile();
}
on createProfile function that gets a uid so value being no longer null.
Actually its working allright if username already exist part, but if its not, for a little moment (i assume during retrieving data ) it getting not-null again.
So output being like this (if type a null username):
good to go
username exists
i dont understand why its giving me "username exists" again ? what would be the solution or any better way.
thanks for your assist..
javascript angular firebase ionic-framework
asked Nov 20 '18 at 15:36
ugrdursunugrdursun
2418
add a comment |
im working on a simple coding here but i kind of stuck.
basicly the code will check if the username exists or not, so im using these codes;
Data Structure;
"usernametouid": {
"username": "userid",
}
Codes;
this.afDatabase.object(`usernametouid/${this.username}`).subscribe(data => {
const dtvl = data.$value;
if(dtvl != null) {
console.log("username exists")
} else if(dtvl == null) {
console.log("good to go")
this.createProfile();
}
on createProfile function that gets a uid so value being no longer null.
Actually its working allright if username already exist part, but if its not, for a little moment (i assume during retrieving data ) it getting not-null again.
So output being like this (if type a null username):
good to go
username exists
i dont understand why its giving me "username exists" again ? what would be the solution or any better way.
thanks for your assist..
javascript angular firebase ionic-framework
asked Nov 20 '18 at 15:36
ugrdursunugrdursun
2418
im working on a simple coding here but i kind of stuck.
basicly the code will check if the username exists or not, so im using these codes;
Data Structure;
"usernametouid": {
"username": "userid",
}
Codes;
this.afDatabase.object(`usernametouid/${this.username}`).subscribe(data => {
const dtvl = data.$value;
if(dtvl != null) {
console.log("username exists")
} else if(dtvl == null) {
console.log("good to go")
this.createProfile();
}
on createProfile function that gets a uid so value being no longer null.
Actually its working allright if username already exist part, but if its not, for a little moment (i assume during retrieving data ) it getting not-null again.
So output being like this (if type a null username):
good to go
username exists
i dont understand why its giving me "username exists" again ? what would be the solution or any better way.
thanks for your assist..
javascript angular firebase ionic-framework
javascript angular firebase ionic-framework
asked Nov 20 '18 at 15:36
ugrdursunugrdursun
2418
asked Nov 20 '18 at 15:36
ugrdursunugrdursun
2418
asked Nov 20 '18 at 15:36
ugrdursunugrdursun
2418
asked Nov 20 '18 at 15:36
ugrdursunugrdursun
2418
asked Nov 20 '18 at 15:36
ugrdursunugrdursun
2418
2418
add a comment |
add a comment |
1 Answer
1
active
oldest
votes
I assume you are using the angularfire2 library.
The this.afDatabase.object('<objectAddress>') returns a FirebaseObjectObservable (which is deprecated btw). This Observable will emit values whenever something changes inside that object.
In your case everything works quite logically.
- You subscribe to the
FirebaseObjectObservable
- The observable emits current value of that object in the database
- At first the value is
null, so you get the output of 'good to go' - You call
this.createProfile();which I guess now creates the profile and changes the object you subscribed to in the database. Setting its"username"to the newly createdid. - Since the object was changed in the database, the
FirebaseObjectObservableemits new value. And your subscription function runs again. This timedata.$valueis notnullas it now contains the newly created id.
If you just want to get the current value of the object once, you could make use of .take(1) RxJS operator. Or .pipe(take(1)) depending on the RxJS version. This makes sure the observable emits only once.
answered Nov 20 '18 at 15:50
Daniil Andreyevich BaunovDaniil Andreyevich Baunov
1,092528
thanks for your well support. I am very happy hence you understood me completely right. but i dont really know where to put that take(1). actually im using it at authstate like this: this.afAuth.authState.take(1).subscribe(auth =>..... but when trying at afdatabase it says take is not available in FirebaseDatabase
– ugrdursun
Nov 20 '18 at 20:57
1
i found by brute-force :) right before ".subscribe" . thanks again for your support, appreciated!
– ugrdursun
Nov 20 '18 at 21:22
@ugrdursun, you are welcome :)
– Daniil Andreyevich Baunov
Nov 20 '18 at 21:57
add a comment |
Your Answer
StackExchange.ifUsing("editor", function () {
StackExchange.using("externalEditor", function () {
StackExchange.using("snippets", function () {
StackExchange.snippets.init();
});
});
}, "code-snippets");
StackExchange.ready(function() {
var channelOptions = {
tags: "".split(" "),
id: "1"
};
initTagRenderer("".split(" "), "".split(" "), channelOptions);
StackExchange.using("externalEditor", function() {
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled) {
StackExchange.using("snippets", function() {
createEditor();
});
}
else {
createEditor();
}
});
function createEditor() {
StackExchange.prepareEditor({
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: true,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: 10,
bindNavPrevention: true,
postfix: "",
imageUploader: {
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
},
onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
});
}
});
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f53396457%2ffirebase-checking-value-if-its-null%23new-answer', 'question_page');
}
);
Post as a guest
Required, but never shown
1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
I assume you are using the angularfire2 library.
The this.afDatabase.object('<objectAddress>') returns a FirebaseObjectObservable (which is deprecated btw). This Observable will emit values whenever something changes inside that object.
In your case everything works quite logically.
- You subscribe to the
FirebaseObjectObservable
- The observable emits current value of that object in the database
- At first the value is
null, so you get the output of 'good to go' - You call
this.createProfile();which I guess now creates the profile and changes the object you subscribed to in the database. Setting its"username"to the newly createdid. - Since the object was changed in the database, the
FirebaseObjectObservableemits new value. And your subscription function runs again. This timedata.$valueis notnullas it now contains the newly created id.
If you just want to get the current value of the object once, you could make use of .take(1) RxJS operator. Or .pipe(take(1)) depending on the RxJS version. This makes sure the observable emits only once.
answered Nov 20 '18 at 15:50
Daniil Andreyevich BaunovDaniil Andreyevich Baunov
1,092528
thanks for your well support. I am very happy hence you understood me completely right. but i dont really know where to put that take(1). actually im using it at authstate like this: this.afAuth.authState.take(1).subscribe(auth =>..... but when trying at afdatabase it says take is not available in FirebaseDatabase
– ugrdursun
Nov 20 '18 at 20:57
1
i found by brute-force :) right before ".subscribe" . thanks again for your support, appreciated!
– ugrdursun
Nov 20 '18 at 21:22
@ugrdursun, you are welcome :)
– Daniil Andreyevich Baunov
Nov 20 '18 at 21:57
add a comment |
I assume you are using the angularfire2 library.
The this.afDatabase.object('<objectAddress>') returns a FirebaseObjectObservable (which is deprecated btw). This Observable will emit values whenever something changes inside that object.
In your case everything works quite logically.
- You subscribe to the
FirebaseObjectObservable
- The observable emits current value of that object in the database
- At first the value is
null, so you get the output of 'good to go' - You call
this.createProfile();which I guess now creates the profile and changes the object you subscribed to in the database. Setting its"username"to the newly createdid. - Since the object was changed in the database, the
FirebaseObjectObservableemits new value. And your subscription function runs again. This timedata.$valueis notnullas it now contains the newly created id.
If you just want to get the current value of the object once, you could make use of .take(1) RxJS operator. Or .pipe(take(1)) depending on the RxJS version. This makes sure the observable emits only once.
answered Nov 20 '18 at 15:50
Daniil Andreyevich BaunovDaniil Andreyevich Baunov
1,092528
thanks for your well support. I am very happy hence you understood me completely right. but i dont really know where to put that take(1). actually im using it at authstate like this: this.afAuth.authState.take(1).subscribe(auth =>..... but when trying at afdatabase it says take is not available in FirebaseDatabase
– ugrdursun
Nov 20 '18 at 20:57
1
i found by brute-force :) right before ".subscribe" . thanks again for your support, appreciated!
– ugrdursun
Nov 20 '18 at 21:22
@ugrdursun, you are welcome :)
– Daniil Andreyevich Baunov
Nov 20 '18 at 21:57
add a comment |
I assume you are using the angularfire2 library.
The this.afDatabase.object('<objectAddress>') returns a FirebaseObjectObservable (which is deprecated btw). This Observable will emit values whenever something changes inside that object.
In your case everything works quite logically.
- You subscribe to the
FirebaseObjectObservable
- The observable emits current value of that object in the database
- At first the value is
null, so you get the output of 'good to go' - You call
this.createProfile();which I guess now creates the profile and changes the object you subscribed to in the database. Setting its"username"to the newly createdid. - Since the object was changed in the database, the
FirebaseObjectObservableemits new value. And your subscription function runs again. This timedata.$valueis notnullas it now contains the newly created id.
If you just want to get the current value of the object once, you could make use of .take(1) RxJS operator. Or .pipe(take(1)) depending on the RxJS version. This makes sure the observable emits only once.
answered Nov 20 '18 at 15:50
Daniil Andreyevich BaunovDaniil Andreyevich Baunov
1,092528
I assume you are using the angularfire2 library.
The this.afDatabase.object('<objectAddress>') returns a FirebaseObjectObservable (which is deprecated btw). This Observable will emit values whenever something changes inside that object.
In your case everything works quite logically.
- You subscribe to the
FirebaseObjectObservable
- The observable emits current value of that object in the database
- At first the value is
null, so you get the output of 'good to go' - You call
this.createProfile();which I guess now creates the profile and changes the object you subscribed to in the database. Setting its"username"to the newly createdid. - Since the object was changed in the database, the
FirebaseObjectObservableemits new value. And your subscription function runs again. This timedata.$valueis notnullas it now contains the newly created id.
If you just want to get the current value of the object once, you could make use of .take(1) RxJS operator. Or .pipe(take(1)) depending on the RxJS version. This makes sure the observable emits only once.
answered Nov 20 '18 at 15:50
Daniil Andreyevich BaunovDaniil Andreyevich Baunov
1,092528
edited Nov 20 '18 at 15:55
answered Nov 20 '18 at 15:50
Daniil Andreyevich BaunovDaniil Andreyevich Baunov
1,092528
answered Nov 20 '18 at 15:50
Daniil Andreyevich BaunovDaniil Andreyevich Baunov
1,092528
answered Nov 20 '18 at 15:50
Daniil Andreyevich BaunovDaniil Andreyevich Baunov
1,092528
1,092528
thanks for your well support. I am very happy hence you understood me completely right. but i dont really know where to put that take(1). actually im using it at authstate like this: this.afAuth.authState.take(1).subscribe(auth =>..... but when trying at afdatabase it says take is not available in FirebaseDatabase
– ugrdursun
Nov 20 '18 at 20:57
1
i found by brute-force :) right before ".subscribe" . thanks again for your support, appreciated!
– ugrdursun
Nov 20 '18 at 21:22
@ugrdursun, you are welcome :)
– Daniil Andreyevich Baunov
Nov 20 '18 at 21:57
add a comment |
thanks for your well support. I am very happy hence you understood me completely right. but i dont really know where to put that take(1). actually im using it at authstate like this: this.afAuth.authState.take(1).subscribe(auth =>..... but when trying at afdatabase it says take is not available in FirebaseDatabase
– ugrdursun
Nov 20 '18 at 20:57
1
i found by brute-force :) right before ".subscribe" . thanks again for your support, appreciated!
– ugrdursun
Nov 20 '18 at 21:22
@ugrdursun, you are welcome :)
– Daniil Andreyevich Baunov
Nov 20 '18 at 21:57
thanks for your well support. I am very happy hence you understood me completely right. but i dont really know where to put that take(1). actually im using it at authstate like this: this.afAuth.authState.take(1).subscribe(auth =>..... but when trying at afdatabase it says take is not available in FirebaseDatabase
– ugrdursun
Nov 20 '18 at 20:57
thanks for your well support. I am very happy hence you understood me completely right. but i dont really know where to put that take(1). actually im using it at authstate like this: this.afAuth.authState.take(1).subscribe(auth =>..... but when trying at afdatabase it says take is not available in FirebaseDatabase
– ugrdursun
Nov 20 '18 at 20:57
1
1
i found by brute-force :) right before ".subscribe" . thanks again for your support, appreciated!
– ugrdursun
Nov 20 '18 at 21:22
i found by brute-force :) right before ".subscribe" . thanks again for your support, appreciated!
– ugrdursun
Nov 20 '18 at 21:22
@ugrdursun, you are welcome :)
– Daniil Andreyevich Baunov
Nov 20 '18 at 21:57
@ugrdursun, you are welcome :)
– Daniil Andreyevich Baunov
Nov 20 '18 at 21:57
add a comment |
Thanks for contributing an answer to Stack Overflow!
- Please be sure to answer the question. Provide details and share your research!
But avoid …
- Asking for help, clarification, or responding to other answers.
- Making statements based on opinion; back them up with references or personal experience.
To learn more, see our tips on writing great answers.
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f53396457%2ffirebase-checking-value-if-its-null%23new-answer', 'question_page');
}
);
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
