Use file and directory properties and properties

%Library.File Class also provides many class methods , You can use these methods to get information about files and directories , Or view or set their properties and properties .

Check whether the files and directories exist

To determine whether a given file exists , Please use Existes() Method and specify the file name as the parameter . for example ：

DHC-APP>write ##class(%File).Exists("e:\temp\")
1

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Again , To find out whether a given directory exists , Please use DirectoryExists() Method , And specify the directory as the parameter . for example ：

DHC-APP>write ##class(%File).DirectoryExists("e:\temp")
1

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As mentioned earlier , These methods are in Unix Treat file or directory names as case sensitive , But in Windows Upper case insensitive . Besides , If you specify part of the file name or directory name , Then the file or directory referenced by this method is relative to the directory of the default global database containing the namespace being used . for example ：

DHC-APP>write ##class(%File).Exists("cache.dat")
1

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View and set file and directory permissions

%Library.File Class provides many class methods , You can use these methods to view or set the permissions of files or directories .

Check whether the file or directory is read-only or writable

Given the file or directory name , If the file or directory is read-only ,ReadOnly() Method returns 1, Otherwise return to 0:

DHC-APP>write ##class(%File).ReadOnly("export.xml")
1
DHC-APP>write ##class(%File).ReadOnly("E:\temp")
0

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Again , Given a file or directory name , If the file or directory can be written , be Writeable() Method returns 1, Otherwise return to 0:

DHC-APP>write ##class(%File).Writeable("export.xml")
0
DHC-APP>write ##class(%File).Writeable("e:\temp")
1

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Make the file or directory read-only or writable ( window )

To make Windows Files or directories on become read-only , Please use SetReadOnly() Method , This method returns a Boolean value indicating success or failure . This method takes three parameters , The second parameter is in Windows Is omitted from . The first parameter is the name of the file or directory . The third parameter is the output parameter . If a negative , It contains the error code returned by the operating system , In case the method fails .

In the following example , Yes SetReadOnly() The call to successfully put the file "e:\temp\config.txt Change to read-only .

DHC-APP>write ##class(%File).ReadOnly("e:\temp\config.txt")
0
DHC-APP>write ##class(%File).SetReadOnly("e:\temp\config.txt",,.return)
1
DHC-APP>write ##class(%File).ReadOnly("e:\temp\config.txt")

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In the following example , Yes SetReadOnly() Call of failed ,Windows The system error code is 5, It means “ Access denied .”

DHC-APP>write ##class(%File).SetReadOnly("C:\",,.return)
0
DHC-APP>w return
-5

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To make Windows Files or directories on can be written , Please use SetWriteable() Method . This method uses the same three parameters , The second parameter is in Windows Is omitted again .

DHC-APP>write ##class(%File).Writeable("e:\temp\config.txt")
0
DHC-APP>write ##class(%File).SetWriteable("e:\temp\config.txt",,.return)
1
DHC-APP>write ##class(%File).Writeable("e:\temp\config.txt")
1

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Make the file or directory read-only or writable (Unix)

stay Unix On , You can also use SetReadOnly() and SetWriteable() Method , But due to the existence of the second parameter , Their behavior is somewhat different .

however , stay Unix in , For the owner 、 Groups and users specify different permissions . To better control file and directory permissions , See the section viewing or setting file and directory properties .

View and set file and directory properties

To view or set the properties of a file or directory at a more detailed level , Please use %Library.File Of Attributes() and SetAttributes() Method . File attributes are represented by a sequence of bits collectively expressed as integers . The meaning of each bit depends on the underlying operating system .

View file and directory properties

%Library.File Of Attributes() Method requires a file name or directory name as a parameter , And return the attribute bit sequence represented by an integer .

The following example is in Windows Running on the system ：

DHC-APP>write ##class(%File).Attributes("cache.dat")
32
DHC-APP>write ##class(%File).Attributes("e:\temp")
16
DHC-APP>write ##class(%File).Attributes("secret.zip")
35
DHC-APP>write ##class(%File).Attributes("e:\temp\config.txt")
32

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In the first example ,32 Express cache.dat It's an archive file . In the second example ,16 Express C:\temp Is a directory . In the third example , More than one bit is set ,35 Express secret.zip It's hidden (2) And read only (1) The archive (32). Add 32 + 2 + 1 = 35.

The following example is in Unix Running on the system :

write ##class(%File).Attributes("/home")
16877

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In this case ,16877 Express /home Is a directory (16384), The owner owns the read (256)、 write in (128) And execution (64) jurisdiction ; Read (32) And execution (8) Group permission ; And read for others (4) And execution (1) jurisdiction . add 16384+256+128+64+32+8+4+1 = 16877.

Set file and directory properties

contrary ,SetAttributes() Method to set the properties of a file or directory , And return a Boolean value to indicate success or failure . This method requires three parameters . The first parameter is the name of the file or directory . The second parameter is an integer , Indicates that the file or directory has the required attributes . The third parameter is the output parameter . If a negative , It contains the error code returned by the operating system , In case the method fails .

The following example is in Windows On , By setting 1 position , Make the document e:\temp\config.txt Become a read-only file :

DHC-APP>write ##class(%File).Attributes("e:\temp\config.txt")
32
DHC-APP>write ##class(%File).SetAttributes("e:\temp\config.txt",33,.return)
1
DHC-APP>write ##class(%File).Attributes("e:\temp\config.txt")
33

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The following example is in Unix On , Set the files in the default directory myfile From 644 Change to full permission (777):

USER>write ##class(%File).Attributes("myfile")
33188
USER>write ##class(%File).SetAttributes("myfile",33279,.return)
1
USER>write ##class(%File).Attributes("myfile")
33279

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By placing the regular file (32768) Value of and owner (448)、 Group (56) And others (7) Add the masks of to calculate the expected attribute value .

View other file and directory properties

%Library.File Other class methods of allow you to check various other properties of files and directories .

GetFileDateCreated() Method returns with $H Format the date the file or directory was created :

DHC-APP>write $zdate(##class(%File).GetFileDateCreated("stream"))
04/11/2020
DHC-APP>write $zdate(##class(%File).GetFileDateCreated("e:\temp"))
03/27/2021

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Be careful :Windows It is currently the only platform to track the actual creation date . Other platforms store the date of the last file state change .

GetFileDateModified() Methods to $H Format returns the modified date of the file or directory :

DHC-APP>write $zdate(##class(%File).GetFileDateModified("cache.dat"))
07/11/2021

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Method returns the size of the file , In bytes :

DHC-APP>write ##class(%File).GetFileSize("e:\temp\config.txt")
220

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GetDirectorySpace() Method returns the amount of free space and total space in the drive or directory . According to the fourth parameter ( It can be 0、1 or 2) Value , Space can be in bytes 、MB( The default value is ) or GB Return... For units . In this case ,2 Represent space with GB Return... For units :

DHC-APP>set status = ##class(%File).GetDirectorySpace("C:", .FreeSpace, .TotalSpace, 2)                                                                          
DHC-APP>write FreeSpace
128.83
DHC-APP>write TotalSpace
247.97

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stay Windows On , If you pass the directory name to this method , The amount of space returned is the amount of space on the entire drive .

about GetDirectorySpace() Method , Any error status returned is an operating system level error . In the following example ,Windows System error code 3 Express “ The system could not find the specified path .”

DHC-APP>set status = ##class(%File).GetDirectorySpace("Q:", .FreeSpace, .TotalSpace, 2)                                                                          
DHC-APP>do $system.Status.DisplayError(status)
 
 error  #83:  Error code =3

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