How to create data model dynamically

Question

I have this Json data I get from server in javascript

var mydata = JSON.parse('["X","Y","Z"]');

Below I have the following data model in javascript..

var mySchemasList = {
    schemas: [new SelectSchemaModel("A", false),
              new SelectSchemaModel("B", false),
              new SelectSchemaModel("C", false)
             ]
};

I want to create this model dynamically by getting data ('A','B','C') from mydata..

Any help is sincerely appreciated..

Thanks

Answer 1

Can't you just do something like the following?

var i
var mySchemaList = {schemas:[]}; 
for (i = 0; i < mydata.length; i++) {
    mySchemaList.schemas.push( new SelectSchemaModel(mydata[i], false) );
}

Answer 2

In javascript, objects and arrays are accessed using the . or [] operators. The following two lines does exactly the same thing:

mySchemasList.schemas;
mySchemasList['schemas'];

Also, each member of an object or array act like a variable on its own. So you can assign values, objects or arrays to them:

mySchemasList = {};

When a variable (or property) is declared but not assigned anything its value is undefined . So you can check simply by:

if (mySchemasList === undefined) mySchemasList = {};

Alternatively you can use || short circuiting since undefined is considered false:

mySchemasList = mySchemasList || {};

putting this all together, the following two examples does exactly the same thing.

Example 1:

var mySchemasList = {
    schemas : []
}

Example 2:

var mySchemasList = {};
mySchemasList.schemas = [];

Now that you've created an array at mySchemasList.schemas you can start pushing other objects into it:

mySchemasList.schemas.push(new SelectSchemaModel("A", false));
mySchemasList.schemas.push(new SelectSchemaModel("B", false));
mySchemasList.schemas.push(new SelectSchemaModel("C", false));

Wrapping it up in a for loop parsing the JSON data, you'd do this:

var mydata = JSON.parse(ajax.responseText);
for (var i=0; i<mydata.length; i++) {
    mySchemasList.schemas.push(new SelectSchemaModel(mydata[i],false));
}