Basic CRUD operations

CRUD shorts for create (insert), read (get), update, delete (remove) - basic database operations. The following contents will explain how to use CRUD on Vasern.

Note: Use perform for multiple operations

Let's use VasernDB in Todo use case example created in Write Schema, Setup Vasern.

const { Todos } = VasernDB;

Insert method

Inserting new records into Document

Todos.insert(newRecords, save = true)

Arguments

• newRecord (Object | Array<Object>): new record/records data
• save (boolean): allow Document to write record to disk right away. If set to false, Document won't write record to disk right away and add to commited transaction list.

Return

• Array<Object>: a list of created records (indicate executing insert process)

Example

var item1 = Todos.insert({
    name: "Setup database for React Native",
    note: "Using Vasern",
    completed: false
})[0];

Get method

Document use Queryable object to work with records. Which use lodash to provide other queries such as include, find, filter, exclude, etc.

Todos.get(lookupQuery)

Arguments

• lookupQuery ( string, Object )
  • (string): match record id with string value
  • (Object): match record properties and values with Object properties and values

Return

• Object: object that match with lookupQuery
• undefined if not found

Example

var todoItem = Todos.get({ name: "Setup database for React Native" });

Update method

Update existing record with new valuse

Todos.update(lookupQuery, newValues, save = true);

Arguments

• lookupQuery ( string | Object )
  • (string): record id
  • (Object): record object that contains id
• save (boolean): allow Document to write record to disk right away. If set to false, Document won't write record to disk right away and add to commited transaction list.

Return

• Object: indicates record is found, and execute update process
• false if item not found

Example

var item1 = Todos.get({ name: "Setup database for React Native" });
Todos.update(item1.id, { completed: true });

Remove method

Remove an existing record from Document's records

Todos.remove(lookupQuery, save = true);

Arguments

• lookupQuery ( string | Object )
  • (string): record id
  • (Object): record object that contains id
• save (boolean): allow Document to write record to disk right away. If set to false, Document won't write record to disk right away and add to commited transaction list.

Return

• boolean: indicate record is found, and execute remove process

Example

var item1 = Todos.get({ name: "Setup database for React Native" });
Todos.remove(item1);

Perform multiple operations

---

This method commits multiple operations and write all at once. Which optimize for performance.

Note: Don't use Todos.insert, Todos.remove or Todos.update in callback block as it will create a separate write process.

function callback(db: { insert, update, remove, get }) {
    // Execute operations
}

Todos.perform(callback);

Arguments

• callback ( Function ): ({ insert, update, remove, get }): execution callback block.
  • insert is a version of Insert method with save = false
  • get is a version of Get method
  • remove is a version of Remove method with save = false
  • update is a version of Update method with save = false

Return

• No returning value

Example

Todos.perform(function(db) {

    // Remove all completed items 
    // and update incompleted item to completed
    Todos.data().forEach(function(item) {
        if (item.completed) {
            db.remove(item)
        } else {
            db.update(item, { completed: true })
        }
    })
})

What's next?

Learn about Queries or see examples