Pass values to string after iterating over array-CodePudding

I have and array with nested objects that i want to iterate through and pass the values to a string. I also want to concat the values with another string, as in the example. Im used to JavaScript and i know that this can be done with a map method there. But i'm struggling to find an equivalent in Python.

So my goal is to dynamically pass the values to the string after iterating the array.

objExpression = [
   {
      'name': 'name',
      'value': id,
      'type': 'S',   
   },
   {
      'name': 'brandCode',
      'value': brandCode,
      'type': 'S',   
   },
   ...
]

 UpdateExpression='SET #' objExpression[0]['name'] '= :'objExpression[0]['name'] ',' '#' objExpression[1]['name'] '= :' objExpression[2]['name'] ...'

#Expected output

UpdateExpression='SET #name = :name, #brandCode = :brandCode'

CodePudding user response：

Probably something like this:

"SET "    ", ".join(f"#{item['name']} = :{item['name']}" for item in objExpression)

which gives

'SET #name = :name, #brandCode = :brandCode'

The above futures:

a list comprehension: [item for item in objExpression].
f-strings: f"#{item} = :{item}"
f-strings with a dict lookup: f"#{item['name']}"
a string concatenation with ", ".join(list_of_strings).

(note: the list_of_strings looks like it's missing its square brackets, [], from the first bullet point. I have turned it into a generator expression, marked by the (), which you can do for some cases. In this cases, the () actually mark the method call of join(), where you can fit a generator expression inside of (the result is an iterable of strings, which works fine for .join()).

CodePudding user response：

This may work for you:

objExpression = [
   {
      'name': 'name',
      'value': 1,
      'type': 'S',   
   },
   {
      'name': 'brandCode',
      'value': 123,
      'type': 'S',   
   }
]

UpdateExpression = 'SET '
tmpExpression = []
for exp in objExpression:
    tmpExpression.append(f"#{exp['name']} = :{exp['name']}")

UpdateExpression  = ', '.join(tmpExpression)

The output:

'SET #name = :name, #brandCode = :brandCode'