1.6.Query Parameter

¶ 1.6.1. Query Filter

Query filter documents specify the conditions that determine which records to select for read, update, and delete operations.

You can use:expressions to specify the equality condition and query operator expressions.

{
  <field1>: <value1>,
  <field2>: { <operator>: <value> },
  ...
}

¶ 1.6.2. $type Operator

All query parameters that start with “$” symbol include $go, $max, $sort, $fit, and $sip. Query parameter is below the Get function of X method, therefore query parameters must be used in the Get function. To manipulate, for instance:

tim.X("test").Get($go:90);

¶ 1.6.3. $go

Jump to the record of the input number.

tim.X("test").Get({$go:90});

¶ 1.6.4. $max ( $max )

The size parameter specifies the size of the return collection in number.

By default, queries in X-Server return all fields in matching documents. To limit the amount of data that X-Server sends to applications, you can include a projection document to specify or restrict fields to return.

For example, set the amount of return data to 10:

tim.X("test").Get({$max:10});

¶ 1.6.5. $sort

sort data.

To retrieve documents in reverse insertion order, issue Get() along with the $sort method with the $natural parameter set to -1, and set to 1 is ascending, as shown in the following example:

tim.X("test").Get({    
  $sort: {
      _t: -1
    }
  })

¶ 1.6.6. $fit

Instead of listing the fields to return in the matching document, you can use a $fit array to exclude specific fields. The following example which only return and include some fields in this array parameter.

tim.X("test").Get({$fit:["name","age"]});

If you do not specify a $fit array, the Get() method returns all fields in the matching documents.

¶ 1.6.7. $sip

Sip is the process of automatically replacing the specified paths in the document with document(s) from other collection(s). We may reference a single document, multiple documents, plain object, multiple plain objects, or all objects returned from a query in other collections. Let's look at an example.

tim.X("test").Get({$sip:"test2"});

¶ 1.6.8. Pagination function

The pagination options can be set as follows:

tim.X("test").Get($max:pageSize,$go:pageSize*pageNumber);

For example, page size is 10 and go to the third page, set $go=$max x 3 = 30

tim.X("test").Get($max:10,$go:30);

Go to the tenth page: set $go=$max x 10 = 100

tim.X("test").Get($max:10,$go:100);

¶ 1.6.9. Query Efficiency

Use natural ordering to retrieve the most recently inserted elements from the collection efficiently.