Difference between revisions of "LGUI2:Data Bindings"
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! pullOnce | ! pullOnce | ||
| A boolean specifying whether Pull should only be done automatically once (e.g. to initialize the value), and then disable autoPull | | A boolean specifying whether Pull should only be done automatically once (e.g. to initialize the value), and then disable autoPull | ||
| + | |- | ||
| + | ! pullHook | ||
| + | | An [[LGUI2:Hook|Event Hook]], minus the "eventHandler". When the hooked event fires, the Data Binding will Pull. | ||
|- | |- | ||
! bufferSize | ! bufferSize | ||
| An integer specifying the maximum length for the string returned by LavishScript. '''Default is 4096''' | | An integer specifying the maximum length for the string returned by LavishScript. '''Default is 4096''' | ||
| + | |- | ||
| + | ! linkBinding | ||
| + | | A JSON object with [[LGUI2:Locate|Element Locator]] properties, plus a "member" property that points to the element's Data Binding to use, as per LavishScript data type members (e.g. ItemsBinding, TextBinding) | ||
|} | |} | ||
Latest revision as of 15:02, 7 October 2020
LavishGUI 2 Data Bindings provide a way to bind certain LavishGUI 2 values, such as the text in a text box, to LavishScript values.
Contents
Defining a Data Binding
A Data Binding is defined either by a JSON object enclosed by {}, or by a string.
As a JSON Object
| Data Binding properties | |
|---|---|
| pullFormat | A LavishScript Data Sequence that retrieves the desired value, e.g. ${MyObject.MyValue} |
| pullReplaceNull | A string to replace a "NULL" pulled value |
| pushFormat | An Array of 2 strings that, with the value in-between, form a command to update the desired value, e.g. [ "MyObject.MyValue:Set[\"", "\"]" ] may form MyObject.MyValue:Set["new value"] |
| pushNullFormat | A string with the command to update the desired value, if it would otherwise update to NULL |
| autoPull | A boolean specifying whether Pull should be done automatically on demand. Default is true |
| autoPush | A boolean specifying whether Push should be done automatically on demand. Default is true |
| pullOnce | A boolean specifying whether Pull should only be done automatically once (e.g. to initialize the value), and then disable autoPull |
| pullHook | An Event Hook, minus the "eventHandler". When the hooked event fires, the Data Binding will Pull. |
| bufferSize | An integer specifying the maximum length for the string returned by LavishScript. Default is 4096 |
| linkBinding | A JSON object with Element Locator properties, plus a "member" property that points to the element's Data Binding to use, as per LavishScript data type members (e.g. ItemsBinding, TextBinding) |
As a String
For simple cases, Data Bindings can be defined as a single string. The string must be a LavishScript object path (Data Sequence without the containing ${}), from which the Data Binding can automatically build the most common Pull and Push settings from. The object is assumed to have a Set method, and the Data Binding will have no special handling for NULL.
For example, given the string MyObject.MyValue, the following will be used:
"pullFormat": "${MyObject.MyValue}"
"pushFormat": [ "MyObject.MyValue:Set[\"", "\"]" ]
Relative Data Bindings
Sometimes, a Data Binding may depend on the object (usually an Element) that owns it. In this case, the lgui2 LGUI2 object provides a DataBindingContext member to refer to the object itself. For example:
"pullFormat":"${LGUI2.DataBindingContext.Metadata.Get[someValue]}"
Examples
A textblock with pull-only Data Binding
- NULL is replaced with an empty string by "pullReplaceNull"
{
"type":"textblock",
"textBinding":{
"pullFormat":"${MyObject.MyValue}",
"pullReplaceNull":""
}
}
A textbox with two-way Data Binding
- NULL is replaced with an empty string for both push and pull
{
"type":"textbox",
"textBinding":{
"pullFormat":"${MyObject.MyValue}",
"pullReplaceNull":"",
"pushFormat":[
"MyObject.MyValue:Set[\"",
"\"]"
],
"pushNullFormat":"MyObject.MyValue:Set[\"\"]"
}
}
LavishGUI 2 Topics
