View source for Offline Query (UBIK WinX)

Compared to [[QUERY|online / server side queries]], offline queries provide a similar capability to query for objects that match the criteria defined by the query objects. The major differences are:
* The querying happens entirely offline without the need of networks;
* Only objects already available on the client can be found as query results.

{{Hint|The [[SYSCLS_OFFLINE_QUERY|offline query classification]] is primarily needed on the Scope of the offline query, rather than on the MetaClass itself, because the client evaluates the classification.}}

== Offline query page ==
[[File:UBIK_WinX_UI_Offline_Query_Page.png|thumb|Offline Query]]
An offline query page looks similar to a regular content page which shows the properties on the left side and the content objects on the right. The unique characteristics of a query page are:
* The properties on the left serve as query criteria;
* The content objects on the right are the evaluated results of the query;
* There is an additional {{key press|Evaluate}} button in the bottom-left corner;
Users can change the query criteria by editing the property values. A press on the {{key press|Evaluate}} button then will re-evaluate the query and show the results on the right side.

== Offline query criteria ==
An offline query criterion is essentially a property on the query object. When evaluating a query, every criterion/property is checked against all result candidates (See [[#Technical_background|technical background]]). A candidate is a match if
* it has all the same properties as the offline query;
{{Attention|This is changed in newer versions {{Version/WinXSince|3.6}}. A not found property is just ignored.}}
* and the values of these properties indicate they are relevant according to the query criteria. (Some types have different ways to interpret what makes a value relevant. See below.)
{{Hint|The value checking of a criterion is ignored during query evaluations under any of the following circumstances.
* The criterion does not have any value specified;
* The criterion type is not supported/unknown. (See below)}}

Several types of criteria are supported on offline queries.
{| class="wikitable" | width = "50%"
|-
!  !! Boolean !! String !! Integer !! Double !! DateTime !! Guid
|- align="center"
| Single Value || ✓ || ✓ || ✓ || ✓ || ✓ || ✓
|- align="center"
| Value Range ||  ||  || ✓ || ✓ || ✓ || 
|}

{{Attention|Only those criteria/properties for which the MetaProperty.IndexCount is greater than 0 support value ranges.}}

=== Single value criterion ===
For most single value criteria, {{UBIK}} considers a candidate as a match if the value of the target property equals the value specified in the criterion.
{{Hint|It is possible to use a single DateTime value in a query criterion. However, since even the smallest differences (in seconds or even milliseconds) matter during an equality check, you might want to consider specifying a range instead.}}

=== String criterion ===
For string criteria, instead of checking for the equality, {{UBIK}} does the following.
* Split the string value defined in a criterion by spaces ({{Code| }}) if possible;
<tabs>
<tab name="Since version 3.5">
* {{Version/WinXSince|3.5}} All of these sub strings must be a part of the string value of the target property in order for the candidate to be a match.
For example, candidate object with a name {{Code|PU112 PD112}} is considered as a match under a name criterion with the value {{Code|PU PD}}, but {{Code|PU112}} is not.
</tab>
<tab name="Older versions">
* As long as at least one of the sub strings is a part of the string value of the target property, the candidate is a match.
For example, candidate objects with names {{Code|PU112}} and {{Code|PD2115}} are both considered as matches under a name criterion with the value {{Code|PU PD}}.
</tab>
</tabs>

<headertabs />

[[File:UBIK_WinX_UI_Offline_Query_Ranged_Double_Criterion.gif|thumb|Ranged criterion for double]]
[[File:UBIK_WinX_UI_Offline_Query_Ranged_DateTime_Criterion.gif|thumb|Ranged criterion for date time]]
=== Value range criterion ===
For types such as numbers or dates, it is sometimes more comfortable to specify ranges for criteria.
* Example 1: Candidate objects with pressure readings {{Code|20}} and {{Code|25}} are both considered as matches under a pressure reading criterion with the value {{Code|20 ⩽ ... ⩽ 25}}.
* Example 2: Candidate objects with start dates {{Code|09-11-2017}} and {{Code|08-12-2017}} are both considered as matches under a start date criterion with the value {{Code|> 08-11-2017}}.


Currently, the following ranges are supported.
* exclusive between (... < value < ...);
* exclusive greater than (value > ...);
* exclusive less than (value < ...);
* inclusive between (... ⩽ value ⩽ ...);
* inclusive greater than (value ⩾ ...);
* inclusive less than (value ⩽ ...);
* in a collection (value is A, B, ... or X, the UI support for this range definition is limited that you can't yet add or remove values in the collection).




== Technical background ==
As mentioned earlier, all offline query criteria are checked against the result candidates. The [[SYSCLS_OFFLINE_QUERY|"METACLASS_IDS"]] property of the query object determines which objects are the candidates.

== Demo videos ==
* [[media:UBIK_WinX_UI_Offline_Query.mp4|Offline querying]]

[[Category:Pages with broken file links|Offline Query (UBIK WinX)]]
[[Category:Version 3.1|Offline Query (UBIK WinX)]]
[[Category:WinX|Offline Query (UBIK WinX)]]