example_mimetype_test.go

Documentation: github.com/gabriel-vasile/mimetype

     1  package mimetype_test
     2  
     3  import (
     4  	"bytes"
     5  	"fmt"
     6  	"os"
     7  
     8  	"github.com/gabriel-vasile/mimetype"
     9  )
    10  
    11  func Example_detect() {
    12  	testBytes := []byte("This random text has a MIME type of text/plain; charset=utf-8.")
    13  
    14  	mtype := mimetype.Detect(testBytes)
    15  	fmt.Println(mtype.Is("text/plain"), mtype.String(), mtype.Extension())
    16  
    17  	mtype, err := mimetype.DetectReader(bytes.NewReader(testBytes))
    18  	fmt.Println(mtype.Is("text/plain"), mtype.String(), mtype.Extension(), err)
    19  
    20  	mtype, err = mimetype.DetectFile("a nonexistent file")
    21  	fmt.Println(mtype.Is("application/octet-stream"), mtype.String(), os.IsNotExist(err))
    22  	// Output: true text/plain; charset=utf-8 .txt
    23  	// true text/plain; charset=utf-8 .txt <nil>
    24  	// true application/octet-stream true
    25  }
    26  
    27  // Considering the definition of a binary file as "a computer file that is not
    28  // a text file", they can differentiated by searching for the text/plain MIME
    29  // in their MIME hierarchy.
    30  func Example_textVsBinary() {
    31  	testBytes := []byte("This random text has a MIME type of text/plain; charset=utf-8.")
    32  	detectedMIME := mimetype.Detect(testBytes)
    33  
    34  	isBinary := true
    35  	for mtype := detectedMIME; mtype != nil; mtype = mtype.Parent() {
    36  		if mtype.Is("text/plain") {
    37  			isBinary = false
    38  		}
    39  	}
    40  
    41  	fmt.Println(isBinary, detectedMIME)
    42  	// Output: false text/plain; charset=utf-8
    43  }
    44  
    45  func Example_whitelist() {
    46  	testBytes := []byte("This random text has a MIME type of text/plain; charset=utf-8.")
    47  	allowed := []string{"text/plain", "application/zip", "application/pdf"}
    48  	mtype := mimetype.Detect(testBytes)
    49  
    50  	if mimetype.EqualsAny(mtype.String(), allowed...) {
    51  		fmt.Printf("%s is allowed\n", mtype)
    52  	} else {
    53  		fmt.Printf("%s is now allowed\n", mtype)
    54  	}
    55  	// Output: text/plain; charset=utf-8 is allowed
    56  }
    57  
    58  // Use Extend to add support for a file format which is not detected by mimetype.
    59  //
    60  // https://www.garykessler.net/library/file_sigs.html and
    61  // https://github.com/file/file/tree/master/magic/Magdir
    62  // have signatures for a multitude of file formats.
    63  func Example_extend() {
    64  	foobarDetector := func(raw []byte, limit uint32) bool {
    65  		return bytes.HasPrefix(raw, []byte("foobar"))
    66  	}
    67  
    68  	mimetype.Lookup("text/plain").Extend(foobarDetector, "text/foobar", ".fb")
    69  	mtype := mimetype.Detect([]byte("foobar file content"))
    70  
    71  	fmt.Println(mtype.String(), mtype.Extension())
    72  	// Output: text/foobar .fb
    73  }
    74
View as plain text