ma-calc with angular expression into ma-switch-img

[shaun]

Hi all,

I'm trying to use ma-calc to evaluate to a true/false and then feed this into an ma-switch-img, but it doesn't seem to work.

ma-switch-img doesn't seem to evaluate the true-false and always picks the default-src.

I've verified that I'm getting 'true' as the output for ma-calc by just doing {{STS1_S1_available}} inline and i see "true" on the page.

Is this something to do with the data type that the angular expression is spitting out? or is there something else I'm missing?

Is there perhaps a better way to do this?

<ma-get-point-value/ point="STS1_Input_S1_Voltage" point-xid="DP_R10_STS1_Input_S1_Voltage">
<ma-calc/ input="STS1_Input_S1_Voltage.value > 200" output="STS1_S1_available">
<ma-switch-img/ point="STS1_S1_available" src-false="/modules/dashboards/web/images/led_circle_black.png" src-true="/modules/dashboards/web/images/led_circle_green.png" default-src="/modules/dashboards/web/images/led_circle_black.png" width="30px">

also, on a side note, is there any better docs about ma-fn than whats in the examples/docs that are included with mango?
What i've read so far doesn't really tell me enough to figure out how it works. There are a few things I could do as a function for code reuse.

Cheers!
-Shaun

[phildunlap]

Hey Shaun,

I'm only so-so with Angular, but I think you could solve this by adding an ng-init to the ma-switch-img like so:

<ma-get-point-value/ point="STS1_Input_S1_Voltage" point-xid="DP_R10_STS1_Input_S1_Voltage">
<ma-calc/ input="STS1_Input_S1_Voltage.value > 200" output="STS1_S1_available">
<ma-switch-img/ ng-init='{{switchPoint={"value":STS1_S1_available, "enabled":point.enabled};""}}' point="switchPoint" src-false="/modules/dashboards/web/images/led_circle_black.png" src-true="/modules/dashboards/web/images/led_circle_green.png" default-src="/modules/dashboards/web/images/led_circle_black.png" width="30px">

The issue is that the "point" on the ma-switch-img needs to be an object with a "value" property to work. There's also some functionality from the enabled property.

[Will Geller]

<ma-switch-img> is designed to be used with a point object that would come directly from <ma-get-point-value>

Therefore what Phillip is showing you is using ng-init to create a object that mimics the point object. While it may work it is probably cleaner to just use a meta data point.

You could just set up a boolean meta data point that returns true when the value of that other point in > 200.

I think it would look something like this:

if (pNum.value > 200) {
    return true
}
else {
    return false
}

Where pNum is set to STS1_Input_S1_Voltage is the script context.

Then you could avoid using ma-calc and just use <ma-get-point-value> with the meta data points xid and <ma-switch-img> with that point object.

I will try to reply back shortly with a good example of using <ma-fn>

[phildunlap]

It seems we switched hats this morning Will :D!

Shaun, using a Meta point will also provide you the benefit of doing statistical rollups of the time in the > 200 condition, should such a thing prove relevant to your application in the future.

[shaun]

Thanks guys... a meta data point sounds like the best bet, but I can't see where I can set the datatype to boolean... I can do binary though, is that what you mean?

[Will Geller]

Yes I meant binary!

cheers
Will

[Jared Wiltshire]

@shaun I'm just going to chime in and mention that you should not forget about the standard angular directives such as ngSrc which is what the switchImg directive uses itself.

<ma-get-point-value point="STS1_Input_S1_Voltage" point-xid="DP_R10_STS1_Input_S1_Voltage"></ma-get-point-value>
<img ng-src="/modules/dashboards/web/images/led_circle_{{STS1_Input_S1_Voltage.value > 200 ? 'green' : 'black'}}.png">

If you need to indicate when the point is disabled or mango is down then you will need a little more code but this should work for the main case.

[shaun]

Thanks all!...

@Jared-Wiltshire thats good to know :) I'm starting to get the hang of angular now and how to embed expressions for simple logic operations now.

In this case, I ended up going with the metadata point @Will-Geller suggested. Works like a charm!
@phildunlap was right too, having historical data is actually very handy in this case, especially for the reporting I'll have to do.

Cheers!