Read and write files example
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Listing for the "Read and write files example" view:
(From the Unicorn blog post: Working with binary files in DataFlex)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 | Use Windows.pkgUse DFClient.pkgUse cCharTranslate.pkgUse seq_chnl.pkgUse File_dlg.pkgUse cTextEdit.pkgDeferred_View Activate_oReadWriteFiles for ;Object oReadWriteFiles is a dbView Set Border_Style to Border_Thick Set Size to 155 533 Set Location to 1 2 Set Label to "Read and write files example" Property String psMyFile Property Integer piOldSize // This is what provides the means to encode/decode base64: Object oTrans is a cCharTranslate End_Object // These two functions - ReadMyFile and WriteMyFile - are where the work // gets done. Function ReadMyFile String sFilePathName Returns Boolean Integer iChn UChar[] ucaData String sFile Boolean bExists // For timing test DateTime dtStart dtEnd Timespan tsDiff // Check file exists File_Exist sFilePathName bExists If not bExists Begin Send UserError ('File "' + sFilePathName + '" was not found') "File not found" Function_Return False End Get Seq_New_Channel to iChn Direct_Input channel iChn ("Binary:" + sFilePathName) If not (SeqEof) Begin // Timing test Move (CurrentDateTime()) to dtStart Read_Block channel iChn ucaData -1 Move (Base64EncodeUCharArray(oTrans(Self), ucaData)) to ucaData Set_Argument_Size (SizeOfArray(ucaData) + 1) Move (UCharArrayToString(ucaData)) to sFile // Timeing test Move (CurrentDateTime()) to dtEnd Move (dtEnd - dtStart) to tsDiff// Showln ("Read: " * String(SpanTotalMilliseconds(tsDiff)) + "ms") End Else Begin Send UserError ('File "' + sFilePathName + '" does not exist or was empty') "File Error" Function_Return False End Close_Output channel iChn Send Seq_Release_Channel iChn Set psMyFile to sFile Function_Return True End_Function Function WriteMyFile String sFilePathName Returns Boolean Integer iChn iPos iResp UChar[] ucaFile String sPath sDir sFile Boolean bExists // For timing test DateTime dtStart dtEnd Timespan tsDiff Move (RightPos("\", sFilePathName)) to iPos If not iPos Begin Send UserError "Could not find folder" "Folder Error" Function_Return False End Move (Left(sFilePathName, (iPos - 1))) to sPath File_Exist sPath bExists If not bExists Begin Send UserError ('Folder "' + sPath + '" does not exist') "Folder Error" Function_Return False End Move (Right(sFilePathName, (Length(sFilePathName) - iPos))) to sFile File_Exist sFilePathName bExists If bExists Begin Move (Right(sFilePathName, (Length(sFilePathName) - iPos))) to sFile Get YesNo_Box ; ('The file "' + sFile + '" already exists in folder' * sPath + '. Do you wish to overwrite it?') ; "Overwrite file?" to iResp If (iResp = MBR_NO) ; Function_Return False End Move (StringToUCharArray(psMyFile(Self))) to ucaFile Move (Base64DecodeUCharArray(oTrans(Self), ucaFile)) to ucaFile // If some other program has the file open (and in some cases, has even // previously had the file open), writing to it may fail, so we catch // that error in order to deal with it ourselves and return "failure" // rather "success", resetting it after the write operation, and use the // ERR global indicator to detect the problem. Send Ignore_Error of Error_Object_Id 32 Move False to Err // Timing test Move (CurrentDateTime()) to dtStart Get Seq_New_Channel to iChn Direct_Output channel iChn ("Binary:" + sFilePathName) Write channel iChn ucaFile Close_Output channel iChn Send Seq_Release_Channel iChn Send Trap_Error of Error_Object_Id 32 // Timing test Move (CurrentDateTime()) to dtEnd Move (dtEnd - dtStart) to tsDiff// Showln ("Write:" * String(SpanTotalMilliseconds(tsDiff)) + "ms") If (Err) Begin Send UserError ('There was an error writing to file "' + sFilePathName + '"') "Write Error" Function_Return False End Function_Return True End_Function // The user interface... Object oOpenDialog is a OpenDialog End_Object Object oSaveAsDialog is a SaveAsDialog End_Object Object oRead is a Form Set Size to 13 390 Set Location to 3 86 Set Label to "File path-name to read:" Set psToolTip to "File path-name to read" Set Label_Justification_Mode to JMode_Right Set Label_Col_Offset to 2 Set Value to ; "C:\Program Files (x86)\DataFlex 19.1\Documentation\Installation_and_Environment_Guide.pdf" Set Prompt_Button_Mode to PB_PromptOn Set peAnchors to anTopLeftRight Procedure Prompt Boolean bOK String sFile Get Show_Dialog of oOpenDialog to bOK If bOK Begin Get File_Name of oOpenDialog to sFile Set Value to sFile End End_Procedure End_Object Object oDoRead is a Button Set Size to 14 47 Set Location to 3 480 Set Label to "Read file" Set peAnchors to anTopRight Procedure OnClick String sFile Boolean bOK Integer iOldSize iNewSize Get_Argument_Size to iOldSize Set piOldSize to iOldSize Set Value of oBase64File to "" Get Value of oRead to sFile Get ReadMyFile sFile to bOK Set Enabled_State of oWrite to bOK Set Enabled_State of oDoWrite to bOK If bOK Begin Get_Argument_Size to iNewSize Set piMaxChars of oBase64File to iNewSize Set Value of oBase64File to (If(bOK, psMyFile(Self), "")) End Else Begin Set_Argument_Size (piOldSize(Self)) Set piMaxChars of oBase64File to (piOldSize(Self)) End Send Info_Box ('File "' + sFile + ; If(bOK, '" was read successfully', '" could not be read')) ; (If(bOK, "Success", "Failure")) End_Procedure End_Object Object oWrite is a Form Set Size to 13 390 Set Location to 20 86 Set Label to "File path-name to write:" Set Label_Justification_Mode to JMode_Right Set Label_Col_Offset to 2 Set Enabled_State to False Set Value to "C:\Temp\MyTestFile.pdf" Set Prompt_Button_Mode to PB_PromptOn Set peAnchors to anTopLeftRight Procedure Prompt Boolean bOK String sFile Get Show_Dialog of oSaveAsDialog to bOK If bOK Begin Get File_Name of oSaveAsDialog to sFile Set Value to sFile End End_Procedure End_Object Object oDoWrite is a Button Set Size to 14 47 Set Location to 20 480 Set Label to "Write file" Set Enabled_State to False Set peAnchors to anTopRight Procedure OnClick String sFile Boolean bOK Get Value of oWrite to sFile If (sFile = "") Begin Send Info_Box "You must enter a file path and name to write to" "Enter Filepath" Procedure_Return End Get WriteMyFile sFile to bOK Set Enabled_State of oWrite to (not(bOK)) Set Enabled_State of oDoWrite to (not(bOK)) If bOK Begin Set Value of oBase64File to "" Set psMyFile to "" Set_Argument_Size (piOldSize(Self)) Set piMaxChars of oBase64File to (piOldSize(Self)) End Send Info_Box ('File "' + sFile + ; If(bOK, '" was written successfully', '" was not written')) ; (If(bOK, "Success", "Failure")) End_Procedure End_Object Object oBase64File is a cTextEdit Set Size to 101 520 Set Location to 46 6 Set Read_Only_State to True Set Label to "Base64 Encoded File (will be gibberish... unless vous parlez base64!):" Set peAnchors to anAll End_ObjectCD_End_Object |
