@collinbrewer/descriptor
v0.3.2
Published
Descriptor is an extensible utility for describing and working with criteria in a unified format.
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Readme
Descriptor.js
Descriptor is an extensible utility for describing and working with criteria in a unified format.
Descriptor is used primarily for:
- Describing datasets with a unified format
- Test if a value matches a Descriptor
- Filter an array for values matching the parameters of the Descriptor
- Idempotent serialization that can be used as unique keys for caching datasets
- Parse and stringify into multiple formats
- Comparing descriptors granularity(which we use for optimizing caches and HTTP requests)
What can you do with it?
Example
var descriptor={entityName:"Todo", predicate:"completed!=true"};
var filter=Descriptor.compile(descriptor);
var uncompletedTodos=todos.filter(filter);
What is provided out of the box?
For pre-built functionality, including default in your project gives you:
- Exports/Imports JSON, SQL and a non-standardized queryString format
- Basic store/collection/object descriptors
Example
Let's say you want to extend Descriptor's capability to include a parameter for logging out what's going on.
Descriptor.register("shouldLog", function(objectInDataset, parameterValue){
if(parameterValue===true)
{
console.log(objectInDataset)
}
return true; // the object passes the criteria for this test
});
Features
- Unified
Provides a high-level, unified interface for describing queries/datasets. - Portable
Outputs discrete, serializable strings that can be used as unique keys. - Extensible
Has standard query features but offers hooks for teaching it new tricks.
Unified
Use Descriptor to describe and represent any dataset.
For example, HTML elements:
var navLinkDescriptor=new Descriptor({
entityName:"a",
predicate:"/href!=null"
});
var links=Descriptor.match(document.body);
Serializable
Descriptor is easily serializable for portability.
new Descriptor({entityName:"Task", sortBy:"dateCompleted"})
// becomes...
/Task?predicate=&sortBy=dateCompleted
Becomes:
{
entityName:"Task",
predicate: [
{dateDue}
],
sortBy:
}
toQueryString()
Outputs:
/Task?predicate={}&sortBy=dateCompleted
Extensible
Descriptor.addComponent("ignore", function(o){
});
The array extensions add the ability to filter a data structure based on the Descriptor definition.
var criteria={
entityName:"Task",
predicate:"dateDue<$NOW",
sortBy:"dateDue",
limit:5
};
var filter=Descriptor.compile(criteria);
var top5OverdueTasks=filter(allTasks);