VERIFY DATA FILE

version 11

VERIFY DATA FILE (structurePath; dataPath; objects; options; method{; tablesArray; fieldsArray})

The VERIFY DATA FILE command carries out a structural check of the objects contained in the 4D data file designated by structurePath and dataPath.

Note: For more information about checking data, please refer to the Design Reference manual.

• structurePath designates the structure file (compiled or not) associated with the data file to be checked. This can be the open structure file or any other structure file. You must pass a complete pathname, expressed with the syntax of the operating system. You can also pass an empty string, in this case a standard Open file dialog box appears so that the user can specify the structure file to be used.

• dataPath designates a 4D data file (.4DD). It must correspond to the structure file defined by the structurePath parameter. Be careful, you can designate the current structure file but the data file must not be the current (open) file. To check whether the data file is open, use the VERIFY CURRENT DATA FILE command. If you attempt to check the current data file with the VERIFY DATA FILE command, an error is generated.

The data file designated is opened in read only. You must make sure that no application accesses this file in write mode, otherwise the results of the check may be distorted.

In the dataPath parameter, you can pass an empty string, a file name or a complete pathname, expressed in the syntax of the operating system. If you pass an empty string, the standard Open file dialog box appears so that the user can specify the file to be checked (note that in this case, it is not possible to select the current data file). If you only pass a data file name, 4D will look for it at the same level as the specified structure file.

• The objects parameter is used to designate which types of objects will be checked. Two types of objects can be checked: records and indexes. You can use the following constants, found in the "Data file maintenance" theme:

- Verify Records (4)

- Verify Indexes (8)

- Verify All No Callback (16)

To verify both the records and the indexes, pass the total of Verify Records+Verify Indexes. The value 0 (zero) can also be used to obtain the same result. The Verify All No Callback option is a special case. It carries out complete internal verification but, for internal reasons, does not allow callback methods. This verification is nevertheless compatible with the creation of a log.

• The options parameter is used to set verification options. A single option is currently available, found in the"Data file maintenance" theme: Do not create log file (16384).

Generally, the VERIFY DATA FILE command creates a log file in XML format (please refer to the end of the description of this command). You can cancel this operation by passing this option. To create the log file, pass 0 in options.

• The method parameter is used to set a callback method that will be called regularly during the verification. If you pass an empty string, no method is called. If the method passed does not exist, the verification is not carried out, an error is generated and the OK variable is set to 0. When it is called, this method receives up to 5 parameters depending on the event type originating the call (see calls table). It is imperative to declare these parameters in the method:

- $1	Longint	Message type (see table)
- $2	Longint	Object type
- $3	Text	Message
- $4	Longint	Table number
- $5	Longint	Reserved

The following table describes the contents of the parameters depending on the event type:

Object type: When an object has been verified, an OK message ($1=2), error ($1=3) or warning ($1=5) can be sent. The object type returned in $2 can be one of the following:

• 0 = undetermined

• 4 = record

• 8 = index

• 16 = structure object (preliminary check of data file).

Special case: When $4 = 0 for $1=2, 3or 5, the message does not concern a table or an index but rather the data file as a whole.

The callback method must also return a value in $0 (Longint), which is used to check the execution of the operation:

- If $0 = 0, the operation continues normally

- If $0 = -128, the operation is stopped without any error generated

- If $0 = another value, the operation is stopped and the value passed in $0 is returned as the error number. This error can be intercepted by an error-handling method.

Two optional arrays can also be used by this command:

• The tablesArray array contains the numbers of the tables whose records are to be checked. It can be used to limit checking to only certain tables. If this parameter is not passed or if the array is empty and the objects parameter contains Verify Records, all the tables will be checked.

• The fieldsArray array contains the numbers of the indexed fields whose indexes are to be checked. If this parameter is not passed or if the array is empty and the objects parameter contains Verify Indexes, all the indexes will be checked. The command ignores fields that are not indexed. If a field contains several indexes, they are all checked. If a field is part of a composite index, the entire index is checked.

You must pass a 2D array in fieldsArray. For each row of the array:

- The element {0} contains the table number,

- The other elements {1...x} contain the field numbers.

By default, the VERIFY DATA FILE command creates a log file in XML format (if you have not passed the Do not create log file option, see the options parameter). Its name is based on that of the data file and it is placed in the "Logs" folder of the database. For example, for a data file named "data.4dd," the log file will be named "data_verify_log.xml."

1. Simple checking of data and indexes:

   VERIFY DATA FILE($StructName;$DataName;Verify Indexes+Verify Records;Do not create log file;"")

2. Complete verification with log file:

   VERIFY DATA FILE($StructName;$DataName;Verify All No Callback;0;"")

3. Checking of records only:

   VERIFY DATA FILE($StructName;$DataName;Verify Records;0;"")

4. Checking of records from tables 3 and 7 only:

   ARRAY LONGINT($arrTableNums;2)
   ARRAY LONGINT($arrIndex;0) `not used but mandatory
   $arrTableNums{1}:=3
   $arrTableNums{2}:=7
   VERIFY DATA FILE($StructName;$DataName;Verify Records;0;"FollowScan";$arrTableNums;$arrIndex)

5. Checking of specific indexes (index of field 1 of table 4 and index of fields 2 and 3 of table 5):

   ARRAY LONGINT($arrTableNums;0) `not used but mandatory
   ARRAY LONGINT($arrIndex;2;0) `2 rows (columns added later)
   $arrIndex{1}{0}:=4 ` table number in element 0
   APPEND TO ARRAY($arrIndex{1};1) `number of 1st field to be checked
   $arrIndex{2}{0}:=5 ` table number in element 0
   APPEND TO ARRAY($arrIndex{2};2) ` number of 1st field to be checked
   APPEND TO ARRAY($arrIndex{2};3) ` number of 2nd field to be checked
   VERIFY DATA FILE($StructName;$DataName;Verify Indexes;0;"FollowScan";$arrTableNums;$arrIndex)

VERIFY CURRENT DATA FILE.

If the callback method does not exist, an error is generated and the system variable OK is set to 0.