Getting One Property Value From Dictionary Based Upon Another Property Value

Close. There are a couple of notes. You should use a!map() instead of dictionaries to help resolve typing mismatch errors. With a dictionary you are probably getting a compare error with a list of variant and boolean. so that line should be more like 

if(toboolean(fn!index(local!myDictionary,"active","")),

Note: "if(predicate = true," and "if(predicate," are logically the same

Line 15 will give you a boolean array of the indices where "active" is true, but wherever you return false, you will get "" returned, so your snippet would return {"Green", ""}. You could store this result and filter out the nulls using filter() or a!forEach(), but I would write this like:

a!localVariables(
  local!myDictionary: {
    a!map(
      item: 1,
      active: true,
      description: "Widget",
      color: "Green"
    ),
    a!Map(
      item: 2,
      active:false,
      description: "another",
      color: "red"
    )
  },
  index(local!myDictionary.color, where(local!myDictionary.active), {})
)

Close. There are a couple of notes. You should use a!map() instead of dictionaries to help resolve typing mismatch errors. With a dictionary you are probably getting a compare error with a list of variant and boolean. so that line should be more like 

if(toboolean(fn!index(local!myDictionary,"active","")),

Note: "if(predicate = true," and "if(predicate," are logically the same

Line 15 will give you a boolean array of the indices where "active" is true, but wherever you return false, you will get "" returned, so your snippet would return {"Green", ""}. You could store this result and filter out the nulls using filter() or a!forEach(), but I would write this like:

a!localVariables(
  local!myDictionary: {
    a!map(
      item: 1,
      active: true,
      description: "Widget",
      color: "Green"
    ),
    a!Map(
      item: 2,
      active:false,
      description: "another",
      color: "red"
    )
  },
  index(local!myDictionary.color, where(local!myDictionary.active), {})
)

You could store this result and filter out the nulls using filter() or a!forEach(),

Could this be a test case (forEach()) IF there were more than one true in the active property? Is this a correct assumption?

Can your expand your question or give an example? I'm not sure what you are asking.

Sure: 

a!localVariables(
  local!myDictionary: {
    a!map(
      item: 1,
      active: true,
      description: "Widget",
      color: "Green"
    ),
    a!Map(
      item: 2,
      active:false,
      description: "another",
      color: "red"
    ),
    a!Map(
      item: 3,
      active:true,
      description: "another des",
      color: "blue"
    )
  },
  index(local!myDictionary.color, where(local!myDictionary.active), {})
)

When you mentioned that you would save the results in a forEach() function, the above code now has two true items, in this instance, utilizing a forEach() would produce a list of {Green,Blue}. Is this correct?

The example you just posted works just fine for your desired outcome.

I was saying you would need a looping function to filter out nulls in your first example if you were to use if(). The if() approach would result in "{"Green", "", "Blue"}". If you wanted just "{"Green", "Blue"}", you would need to get rid of that middle "" element. Here is that example:

a!localVariables(
  local!myDictionary: {
    {
      item: 1,
      active: true,
      description: "Widget",
      color: "Green"},
    {
      item: 2,
      active:false,
      description: "another",
      color: "red"}
  },
  local!tempResults: if(toboolean(fn!index(local!myDictionary,"active","")),
    fn!index(local!myDictionary,"color",null), 
    ""
  ),
  reject(fn!isnull, local!tempResults)
)

Note: At the risk of over-simplification, think of reject() as a specialized a!forEach() in this instance. 

OK, I see what you mean now, thank you for the help!