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August 7, 2015 08:02
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firebase go through
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| <!DOCTYPE html> | |
| <html> | |
| <head> | |
| <title>firebase</title> | |
| </head> | |
| <body> | |
| <script src='https://cdn.firebase.com/js/client/2.2.1/firebase.js'></script> | |
| <script> | |
| // var ref = new Firebase('https://test231.firebaseio.com/'); | |
| // every data has a url | |
| // rootRef = new Firebase('https://test231.firebaseio.com/'); | |
| // usersRef = rootRef.child('users'); | |
| // OR | |
| // usersRef = new Firebase("https://test231.firebaseio.com/users"); | |
| // access a specific data by url | |
| // ageRef = new Firebase("https://test231.firebaseio.com/users/mohan/age"); | |
| // write(save) data | |
| // set the age of mohan to 44 | |
| // ageRef.set(44); | |
| // mohanRef = usersRef.child('mohan'); | |
| // mohanRef.set({ full_name: 'Mohan Lal', age: 50, city: 'Bengaluru' }); | |
| // update data (Can we do any better?) | |
| // update() only updates data at the first child level, | |
| // any data passed in beyond the first child level is a treated as a set() operation. | |
| // mohanRef.update({ job: 'WeeWee' }); | |
| // { full_name: 'Mohan Lal', age: 50, city: 'Bengaluru', job: 'WeeWee' } | |
| // `set()` and `update()` using callbacks | |
| // someRef.set('this is a message', function( err ) { | |
| // if(!err) { | |
| // console.log('Data was updated successfully!'); | |
| // } | |
| // }); | |
| // push data | |
| // At a multi user platform where simultaneously several users are engaging with the same data, | |
| // the use of `set()` might be hazardous. Instead firebase provides `push()` that generates a unique ID | |
| // every time a new child is added to the specified database reference. | |
| // var postsRef = ref.child("posts"); | |
| // `push()` returns the ref to the newly added data | |
| // var refMohanPost = postsRef.push({ | |
| // author: "mohan", | |
| // title: "How to swim in an empty pond" | |
| // }); | |
| // var refLilyPost = postsRef.push({ | |
| // author: "lily", | |
| // title: "You smell like pie" | |
| // }); | |
| // get the unique ID generated | |
| // var mohanPostId = refMohanPost.key(); | |
| // Transaction | |
| // These are useful for "atomic operations". | |
| // Atomically incrementing an upvote | |
| // var upvoteRef = new Firebase(' ... upvote data url ... '); | |
| // upvoteRef.transaction(function (current_value) { | |
| // return (current_value || 0) + 1; | |
| // }); | |
| // Try to create a user for mohan, but only if the user id 'mohan' isn't already taken | |
| // var mohanRef = new Firebase('https://test231.firebaseio.com/users/mohan'); | |
| // mohanRef.transaction(function(currentData) { | |
| // | |
| // if (currentData === null) { | |
| // console.log('User mohan does not exist therefore we can create it.'); | |
| // return { full_name: 'Mohan Lal', age: 50, city: 'Bengaluru' }; | |
| // } else { | |
| // console.log('User mohan already exists.'); | |
| // return; // Abort the transaction i.e. Don't return anything | |
| // } | |
| // | |
| // }, function(error, committed, snapshot) { | |
| // | |
| // if (error) { | |
| // console.log('Transaction failed abnormally!', error); | |
| // } else if (!committed) { | |
| // console.log('We aborted the transaction (because mohan already exists).'); | |
| // } else { | |
| // console.log('User mohan added!'); | |
| // } | |
| // | |
| // console.log("Wilma's data: ", snapshot.val()); | |
| // | |
| // }); | |
| // Offline !!! | |
| // A firebase client also maintains its own local version of it, so everytime it is written to this | |
| // local version first and then client then synchronizes the local version with the database. | |
| // Once connectivity is reestablished, firebase database will receive the appropriate set of events | |
| // so that the client "catches up" with the current server state. | |
| // Read | |
| // usersRef = new Firebase("https://test231.firebaseio.com/users"); | |
| // returns the entire users array | |
| // usersRef.on('value', function(snapshot) { | |
| // console.log( snapshot.val() ); // array | |
| // }, function(err) { | |
| // console.log('Looks like you do not have permission to READ.'); | |
| // }); | |
| // returns the added `child` | |
| // usersRef.on('child_added', function(snapshot) { | |
| // console.log( snapshot.val() ); // array element | |
| // }, function(err) { | |
| // console.log('Looks like you do not have permission to READ.'); | |
| // }); | |
| // And similarly, `child_changed` and `child_removed`. | |
| // `once()` | |
| // firebaseRef.once('value', function (snapshot) { | |
| // // code to handle new value | |
| // }, function (err) { | |
| // // code to handle read error | |
| // }); | |
| // Security Check! | |
| // Below example allows anyone to read/write /users/mohan and its children, but doesn't allow for admin | |
| // { | |
| // "rules": { | |
| // "users": { | |
| // "admin": { | |
| // ".read": false, | |
| // ".write": false | |
| // }, | |
| // "mohan": { | |
| // ".read": true, | |
| // ".write": true | |
| // } | |
| // } | |
| // } | |
| // } | |
| // usersRef = new Firebase("https://test231.firebaseio.com/users"); | |
| // usersRef.authWithCustomToken("MY_AUTH_TOKEN", function(error, authData) { | |
| // if (error) { | |
| // console.log("Authentication Failed!", error); | |
| // } else { | |
| // console.log("Authenticated successfully with payload:", authData); | |
| // } | |
| // }); | |
| // How to check if the user is authenticated or not? | |
| // var authData = usersRef.getAuth(); | |
| // if (authData) { | |
| // console.log("Authenticated!"); | |
| // } | |
| // Parent | |
| // var parentRef = usersRef.parent(); // https://test231.firebaseio.com | |
| // Root | |
| // var rootRef = usersRef.root(); // https://test231.firebaseio.com | |
| // Check out more (here)[https://www.firebase.com/docs/] | |
| // and (here)[https://www.firebase.com/docs/web/api/] | |
| </script> | |
| </body> | |
| </html> |
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