Posted by
Sven Van Caekenberghe-2 on
Sep 28, 2015; 2:34pm
URL: https://forum.world.st/NeoCSV-and-special-handling-for-some-columns-tp4852282p4852345.html
> On 28 Sep 2015, at 15:04, Mariano Martinez Peck <
[hidden email]> wrote:
>
> Imagine something like this:
>
> neoCSVReader := (NeoCSVReader on: stream).
> neoCSVReader
> separator: $,;
> recordClass: PriceRecord;
> addIgnoredField; "<name>"
> addField: #securityUniqueId: ; "<ticker>"
> addField: #date: converter: [ :string | Date readFrom: string readStream pattern: 'yyyymmdd' ]; "<date>"
> addFloatField: #open: ; "<open>"
> addFloatField: #high: ; "<high>"
> addFloatField: #low: ; "<low>"
> addFloatField: #close: ; "<close>"
> addIntegerField: #volume: . "<vol>"
> neoCSVReader skipHeader.
> priceRecords := neoCSVReader upToEnd.
>
>
> The #recordClass: is optional. If not, you can get an array of arrays instead.
> You can add #addIgnoredField for all the ones you want to ignore, then add the #addNumber: etc for the number ones, etc.
Correct.
> To write a default empty value, I would use my own converter. Something like:
>
> addField: #stringcolumn: converter: [ :string | string isEmptyOrNil ifTrue: [ '' ] ];
> addField: #numbercolumn: converter: [ :string | string isEmptyOrNil ifTrue: [ 0 ] ifFalse: [ NeoNumberParser parse: string ] ];
Actually there is NeoCSVReader>>#emptyFieldValue: which you can use the configure the reader (but it counts for all fields).
> Hope this helps.
>
> Cheers,
>
>
>
> On Mon, Sep 28, 2015 at 9:06 AM, Nicolai Hess <
[hidden email]> wrote:
> Hi,
>
> I have two problems I could not solve:
>
> 1. I would like to read only some columns: I have a large file with
> ~30 colums, but I am only interested on ~5 columns
> (not that important, I could pre-process the file) but anyway it would be
> nice to do it in smalltalk.
>
> 2. some columns will contain only strings (quoted values) and some only numbers,
> but the field may be empty, is it possible to define the default "emptyValue" as an
> - empty string for empty fields in the "string column"
> - 0 for empty fields in the "number column"?
>
>
> thanks
> in advance
>
> nicolai
>
>
>
> --
> Mariano
>
http://marianopeck.wordpress.com