I think I'm saving the image to Postgres correctly, but get unexpected results trying to load the image. I don't really know if the error is in save or load.
Here is my Anorm code for saving the image:
def storeBadgeImage(badgeHandle: String, imgFile: File) = {
val cmd = """
|update badge
|set img={imgBytes}
|where handle = {badgeHandle}
"""
var fis = new FileInputStream(imgFile)
var imgBytes: Array[Byte] = Resource.fromInputStream(fis).byteArray
// at this point I see the image in my browser if I return the imgBytes in the HTTP response, so I'm good so far.
DB.withConnection { implicit c =>
{
try {
SQL(cmd stripMargin).on("badgeHandle" -> badgeHandle, "imgBytes" -> imgBytes).executeUpdate() match {
case 0 => "update failed for badge " + badgeHandle + ", image " + imgFile.getCanonicalPath
case _ => "Update Successful"
}
} catch {
case e: SQLException => e.toString()
}
}
}
}
...I get "update succesful", so I presume the save is working (I could be wrong). Here is my code for loading the image:
def fetchBadgeImage(badgeHandle: String) = {
val cmd = """
|select img from badge
|where handle = {badgeHandle}
"""
DB.withConnection { implicit c =>
SQL(cmd stripMargin).on("badgeHandle" -> badgeHandle)().map {
case Row(image: Array[Byte]) => {
"image = " + image
}
case Row(Some(unknown: Any)) => {
println(unknown + " unknown type is " + unknown.getClass.getName) //[B#11be1c6 unknown type is [B
"unknown"
}
}
}
}
...rather than going into the case "Row(image: Array[Byte])" as hoped, it goes into the "Row(Some(unknown: Any))" case. My println outputs "[B#11be1c6 unknown type is [B"
I don't know what type [B is or where I may have gone wrong...
It's an array of byte in Java(byte[]). > "I don't know what type [B".
And You can write match { case Row(Some(image: Array[Byte])) => } too in this case and that might be better.
Or you might be able to do that as follows.
val results: Stream[Array[Byte]] = SQL(cmd stripMargin)
.on("badgeHandle" -> "name")().map { row => row[Array[Byte]]("img") }
...Oops, got the following compile error.
<console>:43: error: could not find implicit value for parameter c: anorm.Column[Array[Byte]]
val res: Stream[Array[Byte]] = SQL(cmd stripMargin).on("badgeHandle" -> "name")().map { row => row[Array[Byte]]("img") }
Unfortunately, scala.Array is not supported by default. If you imitate the way of other types, It works.
implicit def rowToByteArray: Column[Array[Byte]] = {
Column.nonNull[Array[Byte]] { (value, meta) =>
val MetaDataItem(qualified, nullable, clazz) = meta
value match {
case bytes: Array[Byte] => Right(bytes)
case _ => Left(TypeDoesNotMatch("..."))
}
}
}
val results: Stream[Array[Byte]] = SQL(cmd stripMargin)
.on("badgeHandle" -> "name")().map { row => row[Array[Byte]]("img") }
https://github.com/playframework/Play20/blob/master/framework/src/anorm/src/main/scala/anorm/Anorm.scala
Related
I got the result for std::result::Result<Row, sqlx::Error>, I want to check the row is found.
the right code:
let sql = "select id,name from tablename LIMIT 0";
let r = sqlx::query_as::<_, Person>(sql).fetch_one(&pool).await;
if let Err(err) = r {
match err {
sqlx::Error::RowNotFound => println!("Not Found!!!"),
_ => (),
}
}
right way 1:
if let Err(err) = r {
if let sqlx::Error::RowNotFound = err {
println!("Not Found!!!");
}
}
right way 2:
r.map_err(|err| if let sqlx::Error::RowNotFound = err {
println!("Not Found!!!");
});
has the more simplify way?
You can also match like this:
match r {
Err(sqlx::Error::RowNotFound) => println!("Not Found!!!"),
_ => (),
}
You could also look at match guards
I have a string
var str = "1 2 3 4"
and I want to convert it into [Int]. It can be done as follow
let intArray = str.characters.split {$0 == " "}.map(String.init).map { Int($0)!}
Now what if my string is
var invalid = " 1 a 4"
Then, the program will crash with
fatal error: unexpectedly found nil while unwrapping an Optional value
I need to be able to check number and throw number format error in map.
You can use throws, try - throw, do - try - catch and guard (if) for that. Here is the code
var invalid = " 1 a 4"
let intArray: [Int]
do {
intArray = try getIntArray(invalid, delimiter: " ")
}catch let error as NSError {
print(error)
intArray = []
}
func getIntArray(input:String, delimiter:Character ) throws -> [Int] {
let strArray = input.characters.split {$0 == delimiter}.map(String.init)
let intArray = try strArray.map {
(int:String)->Int in
guard Int(int) != nil else {
throw NSError.init(domain: " \(int) is not digit", code: -99, userInfo: nil)
}
return Int(int)!
}
return intArray
}
In getIntArray function, We first convert the input string to string array.
Then when we are converting string array to int array, we are expanding the map closure function parameter to include number format checking and throwing error using "guard".
"guard" can be replaced with "if" too if it is not available
if Int(int) == nil {
throw NSError.init(domain: " \(int) is not digit", code: -99, userInfo: nil)
}
Rather than throwing NSError types, you can create your own Swift native enum conforming to ErrorType where your enumeration contains the error case you would like to explicitly handle. E.g.
enum MyErrors : ErrorType {
case NumberFormatError(String)
}
/* throwing function attempting to initialize an
integer given a string (if failure: throw error) */
func strToInt(str: String) throws -> Int {
guard let myInt = Int(str) else { throw MyErrors.NumberFormatError(str) }
return myInt
}
Example usage within a do-try-catch construct:
func strAsIntArr(str: String) -> [Int]? {
var intArr: [Int] = []
do {
intArr = try str.characters.split {$0 == " "}
.map(String.init)
.map { try strToInt($0) }
} catch MyErrors.NumberFormatError(let faultyString) {
print("Format error: '\(faultyString)' is not number convertible.")
// naturally you could rethrow here to propagate the error
} catch {
print("Unknown error.")
}
return intArr
}
/* successful example */
let myStringA = "1 2 3 4"
let intArrA = strAsIntArr(myStringA)
/*[1, 2, 3, 4] */
/* error throwing example */
let myStringB = "1 b 3 4"
let intArrB = strAsIntArr(myStringB)
/* [], Format error: 'b' is not number convertible. */
Until Swift 2 I used this extension to remove multiple whitespaces:
func condenseWhitespace() -> String {
let components = self.componentsSeparatedByCharactersInSet(NSCharacterSet.whitespaceAndNewlineCharacterSet()).filter({!Swift.isEmpty($0)})
return " ".join(components)
}
but with Swift 2 now I get the error
Cannot invoke 'isEmpty' with an argument list of type '(String)'
How could I now remove multiple spaces with Swift 2?
Thnx!
In Swift 2, join has become joinWithSeparator and you call it on the array.
In filter, isEmpty should be called on the current iteration item $0.
To replace whitespaces and newline characters with unique space characters as in your question:
extension String {
func condenseWhitespace() -> String {
let components = self.componentsSeparatedByCharactersInSet(NSCharacterSet.whitespaceAndNewlineCharacterSet())
return components.filter { !$0.isEmpty }.joinWithSeparator(" ")
}
}
let result = "Hello World.\nHello!".condenseWhitespace() // "Hello World. Hello!"
Because your function does not take any parameter you could make it a property instead:
extension String {
var condensedWhitespace: String {
let components = self.componentsSeparatedByCharactersInSet(NSCharacterSet.whitespaceAndNewlineCharacterSet())
return components.filter { !$0.isEmpty }.joinWithSeparator(" ")
}
}
let result = "Hello World.\nHello!".condensedWhitespace // "Hello World. Hello!"
In Swift 3 there's even more changes.
Function:
extension String {
func condenseWhitespace() -> String {
let components = self.components(separatedBy: NSCharacterSet.whitespacesAndNewlines)
return components.filter { !$0.isEmpty }.joined(separator: " ")
}
}
let result = "Hello World.\nHello!".condenseWhitespace()
Property:
extension String {
var condensedWhitespace: String {
let components = self.components(separatedBy: NSCharacterSet.whitespacesAndNewlines)
return components.filter { !$0.isEmpty }.joined(separator: " ")
}
}
let result = "Hello World.\nHello!".condensedWhitespace
In Swift 4.2 NSCharacterSet is now CharacterSet, and you can omit and use dot syntax:
extension String {
func condenseWhitespace() -> String {
let components = self.components(separatedBy: .whitespacesAndNewlines)
return components.filter { !$0.isEmpty }.joined(separator: " ")
}
}
let result = "Hello World.\nHello!".condenseWhitespace() // "Hello World. Hello!"
Split string to array and then join again in not memory efficient. Its Takes lot of memory. The best way in this case is to scan the given string and perform operations on that. Regular Expression is the advance way to scan a text. For the above conclusion the the solution is given below:
Swift 4.x
extension String {
func removeExtraSpaces() -> String {
return self.replacingOccurrences(of: "[\\s\n]+", with: " ", options: .regularExpression, range: nil)
}
}
Usages
let startingString = "hello world! \n\n I am here!"
let processedString = startingString.removeExtraSpaces()
print(processedString)
Output:
processedString => "hello world! I am here!"
You can Do more according to your own requirements but thing I am pointing out here is to use regular expressions with string rather then create arrays which will consume lot of memory.
Cleanest version. Documented, memory efficient, extremely easy to use.
extension String {
/// Returns a condensed string, with no extra whitespaces and no new lines.
var condensed: String {
return replacingOccurrences(of: "[\\s\n]+", with: " ", options: .regularExpression, range: nil)
}
/// Returns a condensed string, with no whitespaces at all and no new lines.
var extraCondensed: String {
return replacingOccurrences(of: "[\\s\n]+", with: "", options: .regularExpression, range: nil)
}
}
Usage:
let a = " Hello\n I am a string ".condensed
let b = " Hello\n I am a string ".extraCondensed
Output:
a: "Hello I am a string"
b: "HelloIamastring"
SWIFT 3: Cleaner version
extension String {
var condensedWhitespace: String {
let components = self.components(separatedBy: .whitespacesAndNewlines)
return components.filter { !$0.isEmpty }.joined(separator: " ")
}
}
Here is mine: How it's actually worked.
extension String {
func removeExtraSpaces() -> String {
var data = ""
var numberOfSpace = 0
let items = self.getComponents(separatedBy: " ")
for item in items{
if item == " "{
numberOfSpace = numberOfSpace + 1
}else{
numberOfSpace = 0
}
if numberOfSpace == 1 || numberOfSpace == 0 {
data = data + item
//data.append(item)
}
}
return data
}
}
Usages
var message = "What is the purpose of life?"
message = message.removeExtraSpaces()
print(message)
Output:
What is the purpose of life?
var str = "Hello World.\nHello!"
if let regex = try? NSRegularExpression(pattern: "\\s+", options:NSRegularExpression.Options.caseInsensitive)
{
str = regex.stringByReplacingMatches(in: str, options: [], range: NSMakeRange(0, str.count), withTemplate: " ")
}
If I pass an anonymous function as an argument, like e.g. in this code sample:
val someMap = someData.map(line => (line.split("\\|")(0), // key
line.split("\\|")(1) + "|" + // value as string concat
line.split("\\|")(4) + "|" +
line.split("\\|")(9)))
I could catch, e.g. an ArrayIndexOutOfBoundsException like this:
try {
val someMap = someData.map(line => (line.split("\\|")(0), // key
line.split("\\|")(1) + "|" + // value as string concat
line.split("\\|")(4) + "|" +
line.split("\\|")(9)))
} catch {
case e1: ArrayIndexOutOfBoundsException => println("exception in line " )
}
The problem with this is that I do not have access to the inner function's scope. In this case I would like to print the line (from the anonymous function) which caused the exception.
How can I do this? Is there some way of catching an exception within an anonymous function? Is there a way to access the scope of an anonymous function from the outside for debugging purposes?
edit: I'm using Scala 2.9.3
You could use Either
val result =
someData.map {
line =>
try {
val values = (line.split("\\|")(0), // key
line.split("\\|")(1) + "|" + // value as string concat
line.split("\\|")(4) + "|" +
line.split("\\|")(9))
Right(values)
} catch {
case e1: ArrayIndexOutOfBoundsException =>
Left(s"exception in line $line")
}
}
result.foreach {
case (Right(values)) => println(values)
case (Left(msg)) => println(msg)
}
But if you are importing data from a text file, I would try to do it without exceptions (because it's not really exceptional to get invalid data in that case):
val result =
someData.map {
line =>
val fields = line.split("\\|")
if (fields.length < 9) {
Left(s"Error in line $line")
} else {
val values = (fields(0), Seq(fields(1), fields(4), fields(9)))
Right(values)
}
}
result.foreach {
case (Right((key, values))) => println(s"$key -> ${values.mkString("|")}")
case (Left(msg)) => println(msg)
}
Perhaps this will give you some ideas:
try {
val someMap = someData.map { line =>
try {
(line.split("\\|")(0), // key
line.split("\\|")(1) + "|" + // value as string concat
line.split("\\|")(4) + "|" +
line.split("\\|")(9)))
} catch {
case inner: ArrayIndexOutOfBoundsException => {
println("exception in " + line)
throw inner;
}
}
}
} catch {
case outer: ArrayIndexOutOfBoundsException => ...
}
The other answers give nice functional solutions using Either etc. If you were using Scala 2.10, you could also use Try as
val lines = List("abc", "ef");
println(lines.map(line => Try(line(3))));
to get List[Try[Char]], where you can examine each element if it succeeded or failed. (I haven't tried to compile this.)
If for any reasons you prefer exceptions, you need to catch the exception inside the mapping function and rethrow it with information about the line. For example:
// Your own exception class holding a line that failed:
case class LineException(line: String, nested: Exception)
extends Exception(nested);
// Computes something on a line and throw a proper `LineException`
// if the processing fails:
def lineWorker[A](worker: String => A)(line: String): A =
try {
worker(line)
} catch {
case (e: Exception) => throw LineException(line, e);
}
def getNth(lines: List[String], i: Int): List[Char]
= lines.map(lineWorker(_.apply(i)));
val lines = List("abc", "ef");
println(getNth(lines, 1));
println(getNth(lines, 2));
You can also express it using Catch from scala.util.control.Exception:
case class LineException(line: String, nested: Throwable)
extends Exception(nested); // we need Throwable here ^^
import scala.util.control.Exception._
// Returns a `Catch` that wraps any exception to a proper `LineException`.
def lineExceptionCatch[T](line: String): Catch[T]
= handling[T](classOf[Exception]).by(e => throw LineException(line, e));
def lineWorker[A](worker: String => A)(line: String): A =
lineExceptionCatch[A](line)(worker(line))
// ...
First your outer try/catch is useless. If you List (or other structure) is empty, map function won't do anything => no ArrayIndexOutOfBoundsException will be thrown.
As for the inner loop, i would sugest another solution with Scalaz Either:
import scalaz._
import EitherT._
import Id.Id
val someMap = someData.map { line =>
fromTryCatch[Id, (String, String)] {
(line.split("\\|")(0), // key
line.split("\\|")(1) + "|" + // value as string concat
line.split("\\|")(4) + "|" +
line.split("\\|")(9))
}
}
and then chain you operations on List[EitherT[...]]
I have documents with field xyz containing
{ term: "puppies", page: { skip: 1, per_page: 20 } } // not useful as a composite key...
{ page: { skip: 1, per_page: 20 }, term: "puppies" } // different order, same contents
For the sake of determining the "top" values in xyz, I want to map them all to something like
emit('term="puppies",page={ skip: 1, per_page: 20 }', 1); // composite key
but I can't get the embedded objects into a meaningful strings:
emit('term="puppies",page=[object bson_object]', 1); // not useful
Any suggestions for a function to use instead of toString()?
# return the top <num> values of <field> based on a query <selector>
#
# example: top(10, :xyz, {}, {})
def top(num, field, selector, opts = {})
m = ::BSON::Code.new <<-EOS
function() {
var keys = [];
for (var key in this.#{field}) {
keys.push(key);
}
keys.sort ();
var sortedKeyValuePairs = [];
for (i in keys) {
var key = keys[i];
var value = this.#{field}[key];
if (value.constructor.name == 'String') {
var stringifiedValue = value;
} else if (value.constructor.name == 'bson_object') {
// this just says "[object bson_object]" which is not useful
var stringifiedValue = value.toString();
} else {
var stringifiedValue = value.toString();
}
sortedKeyValuePairs.push([key, stringifiedValue].join('='));
}
// hopefully we'll end up with something like
// emit("term=puppies,page={skip:1, per_page:20}")
// instead of
// emit("term=puppies,page=[object bson_object]")
emit(sortedKeyValuePairs.join(','), 1);
}
EOS
r = ::BSON::Code.new <<-EOS
function(k, vals) {
var sum=0;
for (var i in vals) sum += vals[i];
return sum;
}
EOS
docs = []
collection.map_reduce(m, r, opts.merge(:query => selector)).find({}, :limit => num, :sort => [['value', ::Mongo::DESCENDING]]).each do |doc|
docs.push doc
end
docs
end
Given that MongoDB uses SpiderMonkey as its internal JS engine, can't you use JSON.stringify (will work even if/when MongoDB switches to V8) or SpiderMonkey's non-standard toSource method?
(sorry, can't try it ATM to confirm it'd work)
toSource method will do the work, but it adds also brackets.
for a clean document use:
value.toSource().substring(1, value.toSource().length - 1)