Data Storage and Retrieval

Using Newton Data Storage Objects

set operator to select entries marked with only the

'flower

and

'tall

tags; this

query does not select entries missing either tag, nor does it select entries marked
with additional tags:

local myCurs := mySoup:Query({indexPath:'name,

tagSpec: {equal: ['tall, 'flower]}});

Like the

equal

set operator, the

all

set operator specifies a set of tags that entries

must have to be selected; however, the

all

set operator does not exclude entries

marked with additional tags. For example, the query in the following example uses
the

all

set operator to select entries marked with both the

'flower

and

'tall

tags. This query excludes entries missing either of these tags but includes entries
marked with a superset of the

'flower

and

'tall

tags:

local myCurs := mySoup:Query({indexPath:'name,

tagSpec: {all: ['tall, 'flower]}});

The presence of any tag specified by the

none

set operator is sufficient to exclude

that entry from the query result. For example, the following query matches entries
having both of the tags

'flower

and

'tall

but excludes any entry marked with

the

'thorns

tag:

local myCurs := mySoup:Query({indexPath:'name,

tagSpec: {all:['flower, 'tall],

none:['thorns]}});

The following exceptions may be thrown when attempting to query using a tag
spec. If the soup does not have a tags index, a "no tags" exception
|

evt.ex.fr.store| -48027

is thrown. If the tag spec passed as an argument to

the

Query

method has none of the slots

equal

,

any

,

all

, or

none

, an "invalid

tag spec" exception |

evt.ex.fr.store

|

-48028

is thrown.

Querying for Text

11

This section describes how to select entries according to the presence of one or
more strings in any slot. The current system allows you to search entries for string
beginnings, entire strings, or substrings of larger strings.

To select entries according to the presence of one or more specified string
beginnings, add to your query spec a

words

slot containing an array of string

beginnings to be matched. For example, the following code fragment illustrates a
query that returns entries having strings beginning with

"bob"

:

// find words beginning with "bob"
local myCurs := mySoup:Query({words: ["bob"]});