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mozIStorageValueArray

From MDC

This article covers features introduced in Firefox 2

mozIStorageValueArray wraps an array of SQL values, such as a single database row.

You can get the type of a value by calling getTypeOfIndex(), which returns the type of the specified column.

For an introduction see Storage

Contents

mozIStorageValueArray is defined in storage/public/mozIStorageValueArray.idl. It is scriptable and unfrozen (hasn't changed since Mozilla 1.8). mozIStorageStatement implements mozIStorageValueArray.

Inherits from: nsISupports

Note: Be careful! SQLite is not a typed database. Any type can be put into any cell, regardless of the type declared for the column. If you request the data be returned as a different type, SQLite will do its best to convert it, and will return some default value if no conversion is possible. Therefore, while you can't get type errors you may get unexpected data out.

[edit] Method overview

long getTypeOfIndex(in unsigned long aIndex);
long getInt32(in unsigned long aIndex);
long long getInt64(in unsigned long aIndex);
double getDouble(in unsigned long aIndex);
AUTF8String getUTF8String(in unsigned long aIndex);
AString getString(in unsigned long aIndex);
void getBlob(in unsigned long aIndex, out unsigned long aDataSize, [array,size_is(aDataSize)] out octet aData);
boolean getIsNull(in unsigned long aIndex);

[edit] Attributes

Attribute Type Description
numEntries unsigned long The number of entries in the array (each corresponding to a column in the database row).

[edit] Constants

Constant Value Description
VALUE_TYPE_NULL 0 Null data type.
VALUE_TYPE_INTEGER 1 INTEGER data type.
VALUE_TYPE_FLOAT 2 FLOAT data type.
VALUE_TYPE_TEXT 3 TEXT data type.
VALUE_TYPE_BLOB 4 BLOB data type.

[edit] Methods

[edit] getTypeOfIndex()

Returns the type of the value at the given column index; one of VALUE_TYPE_NULL, VALUE_TYPE_INTEGER, VALUE_TYPE_FLOAT, VALUE_TYPE_TEXT, or VALUE_TYPE_BLOB. 

 long getTypeOfIndex(
   in unsigned long aIndex
 );
[edit] Parameters
aIndex
The index of the column whose type you wish to determine.
[edit] Return value

One of VALUE_TYPE_NULL, VALUE_TYPE_INTEGER, VALUE_TYPE_FLOAT, VALUE_TYPE_TEXT, or VALUE_TYPE_BLOB.

[edit] getInt32()

Returns an Int32 value for the given entry (column) index. Due to SQLite's type conversion rules, any of these are valid for any column regardless of the column's data type. However, if the specific type matters, call getTypeOfIndex() first to identify the column type, and then the appropriate get method should be called. 

 long getInt32(
   in unsigned long aIndex
 );
[edit] Parameters
aIndex
The index of the column whose value is to be returned.
[edit] Return value

Returns an Int32 value for the given entry (column) index.

[edit] getInt64()

Returns an Int64 value for the given entry (column) index. Due to SQLite's type conversion rules, any of these are valid for any column regardless of the column's data type. However, if the specific type matters, call getTypeOfIndex() first to identify the column type, and then the appropriate get method should be called. 

 long long getInt64(
   in unsigned long aIndex
 );
[edit] Parameters
aIndex
The index of the column whose data should be retrieved.
[edit] Return value

Returns an Int64 value for the given entry (column) index.

[edit] getDouble()

Returns a Double value for the given entry (column) index. Due to SQLite's type conversion rules, any of these are valid for any column regardless of the column's data type. However, if the specific type matters, call getTypeOfIndex() first to identify the column type, and then the appropriate get method should be called. 

 double getDouble(
   in unsigned long aIndex
 );
[edit] Parameters
aIndex
The column's index.
[edit] Return value

Returns a Double value for the given entry (column) index.

[edit] getUTF8String()

Returns an AUTF8String value for the given entry (column) index. Due to SQLite's type conversion rules, any of these are valid for any column regardless of the column's data type. However, if the specific type matters, call getTypeOfIndex() first to identify the column type, and then the appropriate get method should be called.

If you ask for a string value for a NULL column, you will get an empty string with IsVoid set to distinguish it from an explicitly set empty string. 

 AUTF8String getUTF8String(
   in unsigned long aIndex
 );
[edit] Parameters
aIndex
The column's index.
[edit] Return value

Returns an AUTF8String value for the given entry (column) index.

[edit] getString()

Returns an AString value for the given entry (column) index. Due to SQLite's type conversion rules, any of these are valid for any column regardless of the column's data type. However, if the specific type matters, call getTypeOfIndex() first to identify the column type, and then the appropriate get method should be called.

If you ask for a string value for a NULL column, you will get an empty string with IsVoid set to distinguish it from an explicitly set empty string. 

 AString getString(
   in unsigned long aIndex
 );
[edit] Parameters
aIndex
The column's index.
[edit] Return value

Returns an AString value for the given entry (column) index.

[edit] getBlob()

Retrieves unformatted data from the column specified by the given index. The returned data is NULL if dataSize = 0. 

 void getBlob(
   in unsigned long aIndex,
   out unsigned long aDataSize,
   [array,size_is(aDataSize)] out octet aData
 );
[edit] Parameters
aIndex
The column's index.
aDataSize
The size of the returned data.
aData
The returned data.

[edit] getIsNull()

Checks if given column index is NULL or not. 

 boolean getIsNull(
   in unsigned long aIndex
 );
[edit] Parameters
aIndex
The column's index.
[edit] Return value

Returns true or false depending on whether or not the data in the column specified by aIndex is null.

[edit] Example: Using get functions to retrieve values

[edit] C++

PRBool hasMoreData;
while (NS_SUCCEEDED(statement->ExecuteStep(&hasMoreData)) && hasMoreData) {
  PRInt32 value = statement->AsInt32(0);
  // use the value...
}

[edit] JavaScript

while (statement.executeStep()) {
  var value = statement.getInt32(0);
  // use the value...
}

[edit] See also

Retrieved from "http://developer.mozilla.org/en/docs/mozIStorageValueArray"