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  • TAFFY Working with data

    Working with data

    Creating your database

    You use the global TAFFY function to create a new database.

    // Create a new empty database
    var db = TAFFY();
    
    // Create a new database a single object (first record)
    var db = TAFFY({record:1,text:"example"})
    
    // Create a new database using an array
    var db = TAFFY([{record:1,text:"example"}])
    
    // Create a new database using a JSON string
    var db = TAFFY('[{"record":1,"text":"example"}]')
    

    DB Queries

    Once you have a database you'll be able to call your variable as function. This will setup a query and return a collection of methods to work with the results of that query.

    db() Takes:
    One or more Strings, Records, A Filter Objects, Arrays, or Functions.
    Returns:
    A Query Object
    Used to query the database and return a method collection to start working with the data.
    db(); // returns all rows
    

    DB Methods

    In addition to the query function you have a couple of top level methods to use.

    db.insert() Takes:
    An object or array of objects/json strings to insert.

    Optional: Call Event override
    true runs onInsert event (default)
    false does not onInsert event
    Returns:
    A query pointing to the inserted records
    Inserts records into the database.
    db.merge() Takes:
    An object or array of objects/json strings to insert.

    Optional: Key
    identity column to be used to match records against the existing db. Default "id".
    true runs onInsert for new records and onUpdate for changed records

    Optional: Call Event override
    false does not run insert or update event (default)
    true runs onInsert for new records and onUpdate for changed records
    Returns:
    A query pointing to the changed or inserted records
    Inserts or replaces records in an existing db.
    db.insert({column:"value"}); // inserts one record
    						
    db.insert({column:"value"},false); // insert but do not call onInsert event
    db.order() Takes:
    A string listing columns to order by separated by commas.
    Optional: Use asec, desc, logical, and logicaldesc to influencence sort direction.
    Returns:
    true
    Sorts the db by column. Note that logical sorting is default.
    Note: db.sort() is different than db().order() in that sort() changes the order of the records in the database while order() only impacts the order of results returned from a query.
    db.order("columnname"); // orders collection by columnname
    db.store() Takes:
    A string with the storage name for the DB
    Returns:
    true if data was returned from localStorage, false if no data returned
    Sets up a localStorage collection for a given name. If data exists already the data will be loaded into the collection. Changes are auto synced to localStorage.

    Pass in false to terminate storing the collection (data in localstorage will be unchanged).

    Note: localStorage is not avaliable in all browsers. If localStorage is not found then .store() will be ignored.
    db.store("name"); // starts storing records in local storage
    db.settings() Takes:
    An object.
    Returns:
    The settings object
    Used to modify the following settings on each DB:
    • template: this is a template object {} that is merged with each new record as it is added
    • forcePropertyCase: (defaults null) Can be "lower" or "higher" and forces properties to a case on insert, update.
    • onInsert: function to run on record insert. The this keyword will be the new record.
    • onUpdate: function to run on record update. The this keyword will be the new record. Arg 1 will be old record. Arg 2 will be the changes.
    • onRemove: function to run on record remove. The this keyword will be the removed record.
    • onDBChange: function to run on change to the DB. The this keyword will be the entire DB.
    • cacheSize: size of cached query collection. Default to 100. Set to 0 to turn off caching.
    • name: string name for the db table to be used at a later date.
    db.settings({template:{show:true}}); // sets the template to have a show value set to true by default on all records
    
    db.settings({onUpdate:function () {alert(this)}}); // sets the onUpdate event
    
    					

    Query Object Methods

    Any call to data collections root function will return a new query object. The methods below can be used to interact with the data.

    db().update() Takes:
    Any:
    An object to be merged with the matching objects.
    A function that will return the modified record for update.
    Two arguments: a string column name and a value to set the column to

    Optional Call Event override
    true runs onUpdate event (default)
    false does not onUpdate event
    Returns:
    Query Object
    Updates the records in the query set.
    db().update({column:"value"}); // sets column to "value" for all matching records
    
    db().update("column","value"); // sets column to "value" for all matching records
    
    db().update(function () {this.column = "value";return this;}); // sets column to "value" for all matching records
    
    
    db().update({column:"value"},false); // update but do not call onUpdate event
    db().remove() Takes:

    Optional Call Event override
    true runs onUpdate event (default)
    false does not onUpdate event
    Returns:
    Count of removed records.
    Removes records from the database
    db().remove(); // removes all matching records from the database
    						
    db().remove(true); // removes but do not call onRemove event
    db().filter() Takes:
    One or more Strings, Records, A Filter Objects, Arrays, or Functions.
    Returns:
    Query Object
    See Filtering
    Applies a sub filter and returns a new Query Object to let you access the results of the filter.
    db().filter({column:value});
    						
    db().filter({column:value}).count();
    
    collection({column:{gte:value}}).filter({column:{lte:value}}).count();
    					
    db().order() Takes:
    A string listing columns to order by separated by commas.
    Optional: Use asec, desc, logical, and logicaldesc to influence sort direction.
    Returns:
    Query Object
    Sorts the query results by column based. Note that logical sorting is default. Note: db.sort() is different than db().order() in that sort() changes the order of the records in the database while order() only impacts the order of results returned from a query.
    db().order("col1"); // sorts by col1 using a logical sort
    
    db().order("col1 asec, col2 asec"); // sorts by col1 then col2
    
    db().order("col1 desc"); // sorts by col1 descending
    
    db().order("col1 logicaldesc"); // sorts by col1 using a logical sort descending
    					
    db().limit() Takes:
    A number.
    Returns:
    Query Object
    Limits the number of results in a query set.
    db().limit(15); // Limits returned results to first 15
    db().start() Takes:
    A number.
    Returns:
    Query Object
    Sets the starting record number. Used for offset and paging.
    db().start(15); // Starts returning results at record 15
    db().each() Takes:
    A function.
    Returns:
    Query Object
    Runs one or more functions once for every record in the query.
    db().each(function (record,recordnumber) {
    	alert(record["balance"]);
    }); // alerts the value of the balance column for each record
    db().map() Takes:
    A function.
    Returns:
    An array of results from your function being run against the records in the query.
    Runs your function against each record in the query and returns the results as an array.
    db().map(function (record,recordnumber) {
    	return record.balance*0.2;
    }); // returns an array of numbers that are each 20% of the actual balance for each record
    db().callback() Takes:
    A function and an (optional) delay.
    Used for lazy query execution and to prevent blocking. Provided function will be called with current Quote Object after query has run in a setTimeout block.
    db().callback(function () {
        alert(this.count()); // alert count of matching records					
    });
    db().get() Returns:
    An array of all matching records.
    Prefered method for extracting data. Returns an array of matching records. Also used for exporting records form the database.
    db().get(); // returns an array of all matching records
    db().stringify() Returns:
    A JSON representation of an array of all matching records.
    Used for exporting data as JSON text. Returns a JSON array filled with JSON objects for each record.
    db().stringify(); // returns a JSON array of all matching records
    db().first() Returns:
    A single record.
    Returns the first record in a record set.
    db().first(); // returns the first record out of all matching records.
    db().last() Returns:
    A single record.
    Returns the last record in a record set.
    db().last(); // returns the last record out of all matching records.
    db().sum() Takes:
    One or more column names.
    Returns:
    A number.
    Returns the sum total of the column or columns passed into it.
    db().last("balance"); // returns the sum of the "balance" column.
    db().min() Takes:
    Column name.
    Returns:
    A number or value.
    Returns the min value for the column passed in.
    db().min("balance"); // returns the lowest value of the "balance" column.
    db().max() Takes:
    Column name.
    Returns:
    A number or value.
    Returns the max value for the column passed in.
    db().max("balance"); 
    // returns the highest value of the "balance" column.
    db().select() Takes:
    One or more column names.
    Returns:
    For one column: An array of values.
    For two or more columns: An array of arrays of values.
    Used to select columns out the database. Pass in column names to get back an array of values.
    db().select("charges","credits","balance"); 
    // returns an array of arrays in this format [[-24,20,-4]]
    
    db().select("balance"); 
    // returns an array of values in this format [-4,6,7,10]
    					
    db().distinct() Takes:
    One or more column names.
    Returns:
    For one column: An array of values.
    For two or more columns: An array of arrays of values.
    Used to select distinct values from the database for one or more columns. Pass in column names to get back an array of distinct values.
    db().distinct("title","gender"); 
    // returns an array of arrays in this format [["Mr.","Male"],["Ms.","Female"]]
    
    db().distinct("title"); 
    // returns an array of values in this format ["Mr.","Ms.","Mrs."]
    db().supplant() Takes:
    A string template.
    Optional return array flag.
    Returns:
    Defaults to a string. If return array flag is true then an array of strings with an entry for each record.
    Used to merge records with a template formated with {key} values to be replaced with real values from the records.
    db().supplant("<tr><td>{balance}</td></tr>"); 
    // returns a string in this format "<tr><td>-4</td></tr><tr><td>6</td></tr>"
    
    db().supplant("<tr><td>{balance}</td></tr>",true); 
    // returns an array of strings format ["<tr><td>-4</td></tr>","<tr><td>6</td></tr>"]
    
    db().join() Takes:
    1. A second db or reference to a db query.
    2. One or more functions to be used as join conditions or
    An an array of one or more join conditions
    Returns:
    A db query object containing the joined rows.
    Used to join two dbs and/or queries together and produce a hybrid query containing the joined data.

    [EXPERIMENTAL FEATURE]
    // City DB
    city_db = TAFFY([
      {name:'New York',state:'NY'},
      {name:'Las Vegas',state:'NV'},
      {name:'Boston',state:'MA'}
    ]);
    
    // State DB
    state_db = TAFFY([
      {name: 'New York', abbreviation: 'NY'},
      {name: 'Nevada', abbreviation: 'NV'},
      {name: 'Massachusetts', abbreviation: 'MA'}
    ]);
    
    // Conditional Join
    city_db()
      .join( state_db, [ 'state', 'abbreviation' ]);
    
    // Conditional Join with optional ===
    city_db()
      .join( state_db, [ 'state', '===', 'abbreviation' ]);
      
    // Conditional Join using function
    city_db()
      .join( state_db, function (l, r) {
          return (l.state === r.abbreviation);
        });
    
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  • 原文地址:https://www.cnblogs.com/William_Fire/p/2733254.html
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