Hello @evan.8585
An expression is created from the shapefile's database file, that's the dbf component of the SHAPEFILE. (The other parts are shp, shx and prj.) So if you want an expression from the SPAN linework (that's the span geometry which is technically the SPAN.shp) you'll need to acquire the 'DATA' from the span dbf. You can't create an expression from the FIBER_CABLE's dbf and use it to label the SPAN.shp linework. You could, with know-how, merge the SPAN and FIBER_CABLE shapefiles which would effectively combine the attributes of both dbf's but it's not what I'd call efficient. You'd be doing all that work just to create a label and that's just not worth it. That doesn't mean it can't be done, I'd just find another way of doing it--using DATA that's not from the shapefile's dbf.
It's worth reviewing the data attributes of your three shapefiles: Pole, Span and Fiber_Cable. Generally speaking, your expressions are created by the tabular data or the columns (the column headings are your attributes, also called FIELDS). You can create calculations from the attributes, some examples include, but are not limited to, fieldA+fieldB, greater then or less than, etc., etc.....
The image below are the attributes from SPAN.dbf. Notice the <Null> values. Null means there's a field for data, but the data field is not 'filled in.' Maybe the data wasn't collected, maybe it was collected but it wasn't entered into the databse or maybe someone #&@%'d up and deleted the data leaving only the column heading for other users. Whatever.....it looks lousy, not meaningful to those who may want to use it. Lot's and lot's of data placeholders but they're empty, not filled in. (The slider bar at the bottom reveals more columns.) Some even have zeros which probably means someone filled it in but entered '0' instead of a real world, meaningful value. BTW, you can't access the data if it's not stored to begin with. Where's your column for span? Is the SPAN column <Null>? Refer to image-1.
Image-1: The database file (dbf) of the SCAN shapefile.
One final word on DATA. For your Annotation Template to be useful, you'll need to have the attribute name identical from datafile-to-datafile. For example, owner vs. owned_by vs. OwnedBy would mess up your 'reusable' template and if you can't reuse it, what's the point in creating one in the first place?
<<Remember your previous post, you want to create it, use it, file it away then use it over and over again because you seek automation, yes?>>
How is it messed up? Those 3 attributes are not the same. They might mean the same thing to you, me and everyone else, but when used in an expression, owner is not the same as owned_by and not the same as OwnedBy. Do you feel confident your data will be collected AND stored in a way that's reusable? Because if it's messed up, you'd need three separate Anno Templates to read each attribute! You might as well call the attributes Moe, Larry and Curly. Automated? It doesn't look like it.
Yes, you can SAVE an expression. A good place to save it is in your project folder. Saving it in a centralized location so it can be used in other projects will have the limitations described in the previous paragraph. Once it's saved you can reuse it. Refer to image-2.
Image-2: Save and Load an expression can be done through Options.
They 1st KEY is having organized data attributes to begin with and that involves (1) a well thought out plan to establish the attributes you know you'll need, (2) an organized way to store the data, and (3) a plan to retrieve the data after you've managed to store it. Yes, yes, I know, I know, you didn't create or collect the data, you're just a data user, the guy pushing a mouse. The 2nd KEY is to have 'reliable' data. As you already know, some online downloadable data is reliable, while others not so much. Bookmark the reliable ones. In the absence of good data, it probably best to create or formulate your own.
For good documentation, I don't have any recommendations aside from searching the web and hiring a consultant. Yeah, expensive, but with the right one, it's worth it. You can download know hows here-and-there saving them to your hard drive. Print hardcopies and build a library. If your office has 'binding' capabilities (such as binding for outgoing reports) make your own text books. Search for videos too. It's hit-and-miss with videos. The videos might not cover what you really and truly want to learn while some are only made by those who just wanna be video stars.
And don't forget this forum, it's an indispensable resource especially if you're open minded and willing to look at other ways (some are advanced methods you'd never ever consider) to do the job. It's a free education, don't squander it.
Chicagolooper
