Applies a filter to the Items collection, returning a new collection containing all of the items from the original that match the filter.
Assembly: Microsoft.Office.Interop.Outlook (in Microsoft.Office.Interop.Outlook.dll)
Return valueType: Microsoft.Office.Interop.Outlook.Items
An Items collection that represents the items from the original Items collection which match the filter.
This method is an alternative to using the Find method or FindNext method to iterate over specific items within a collection. The Find or FindNext methods are faster than filtering if there are a small number of items. The Restrict method is significantly faster if there is a large number of items in the collection, especially if only a few items in a large collection are expected to be found.
If you are using user-defined fields as part of a Find or Restrict clause, the user-defined fields must exist in the folder. Otherwise the code will generate an error stating that the field is unknown. You can add a field to a folder by displaying the Field Chooser and clicking New.
This method cannot be used and will cause an error with the following properties:
Creating Filters for the Find and Restrict Methods
The syntax for the filter varies depending on the type of field you are filtering on.
String (for Text fields)
When searching Text fields, you can use either an apostrophe ('), or double quotation marks (""), to delimit the values that are part of the filter. For example, all of the following lines function correctly when the field is of type String (string in C#):
sFilter = "[CompanyName] = 'Microsoft'"
sFilter = "[CompanyName] = ""Microsoft"""
sFilter = "[CompanyName] = " & Chr(34) & "Microsoft" & Chr(34)
In specifying a filter in a Jet or DASL query, if you use a pair of single quotes to delimit a string that is part of the filter, and the string contains another single quote or apostrophe, then add a single quote as an escape character before the single quote or apostrophe. Use a similar approach if you use a pair of double quotes to delimit a string. If the string contains a double quote, then add a double quote as an escape character before the double quote.
For example, in the DASL filter string that filters for the Subject property being equal to the word can't, the entire filter string is delimited by a pair of double quotes, and the embedded string can't is delimited by a pair of single quotes. There are three characters that you need to escape in this filter string: the starting double quote and the ending double quote for the property reference of http://schemas.microsoft.com/mapi/proptag/0x0037001f, and the apostrophe in the value condition for the word can't. Applying the appropriate escape characters, you can express the filter string as follows:
filter = "@SQL=""http://schemas.microsoft.com/mapi/proptag/0x0037001f"" = 'can''t'"
Alternatively, you can use the chr(34) function to represent the double quote (whose ASCII character value is 34) that is used as an escape character. Using the chr(34) substitution for a double-quote escape character, you can express the last example as follows:
filter = "@SQL= " & Chr(34) & "http://schemas.microsoft.com/mapi/proptag/0x0037001f" _
& Chr(34) & " = " & "'can''t'"
Escaping single and double quote characters is also required for DASL queries with the ci_startswith or ci_phrasematch operators. For example, the following query performs a phrase match query for can't in the message subject:
filter = "@SQL=" & Chr(34) & "http://schemas.microsoft.com/mapi/proptag/0x0037001E" _
& Chr(34) & " ci_phrasematch " & "'can''t'"
Another example is a DASL filter string that filters for the Subject property being equal to the words the right stuff, where the word stuff is enclosed by double quotes. In this case, you must escape the enclosing double quotes as follows:
filter = "@SQL=""http://schemas.microsoft.com/mapi/proptag/0x0037001f"" = 'the right ""stuff""'"
A different set of escaping rules apply to a property reference for named properties that contain the space, single quote, double quote, or percent character. For more information, see Referencing Properties by Namespace.
Although dates and times are typically stored with a Date format, the Find and Restrict methods require that the date and time be converted to a string representation. To make sure that the date is formatted as Microsoft Outlook expects, use the Format function. The following example creates a filter to find all contacts that have been modified after January 15, 1999 at 3:30 P.M.
sFilter = "[LastModificationTime] > '" & Format("1/15/99 3:30pm", "ddddd h:nn AMPM") & "'"
Boolean operators, TRUE/FALSE, YES/NO, ON/OFF, and so on, should not be converted to a string. For example, to determine whether journaling is enabled for contacts, you can use this filter:
sFilter = "[Journal] = True"
If you use quotation marks as delimiters with Boolean fields, then an empty string will find items whose fields are False and all non-empty strings will find items whose fields are True.
Keywords (or Categories)
The Categories field is of type keywords, which is designed to hold multiple values. When accessing it programmatically, the Categories field behaves like a Text field, and the string must match exactly. Values in the text string are separated by a comma and a space. This typically means that you cannot use the Find and Restrict methods on a keywords field if it contains more than one value. For example, if you have one contact in the Business category and one contact in the Business and Social categories, you cannot easily use the Find and Restrict methods to retrieve all items that are in the Business category. Instead, you can loop through all contacts in the folder and use the Instr function to test whether the string "Business" is contained within the entire keywords field.
A possible exception is if you limit the Categories field to two, or a low number of values. Then you can use the Find and Restrict methods with the OR logical operator to retrieve all Business contacts. For example (in pseudocode): "Business" OR "Business, Personal" OR "Personal, Business." Category strings are not case sensitive.
You can search for Integer fields with, or without quotation marks as delimiters. The following filters will find contacts that were created using Outlook 2000:
sFilter = "[OutlookInternalVersion] = 92711"
sFilter = "[OutlookInternalVersion] = '92711'"
Using Variables as Part of the Filter
As the Restrict method example illustrates, you can use values from variables as part of the filter. The following Microsoft Visual Basic code sample illustrates syntax that uses variables as part of the filter.
sFullName = "Dan Wilson"
' This approach uses Chr(34) to delimit the value.
sFilter = "[FullName] = " & Chr(34) & sFullName & Chr(34)
' This approach uses double quotation marks to delimit the value.
sFilter = "[FullName] = """ & sFullName & """"
Using Logical Operators as Part of the Filter
Logical operators that are allowed are AND, OR, and NOT. The following are variations of the clause for the Restrict method so you can specify multiple criteria.
OR: The following code returns all contact items that have either Business or Personal as their category.
sFilter = "[Categories] = 'Personal' Or [Categories] = 'Business'"
AND: The following code retrieves all personal contacts who work at Microsoft.
sFilter = "[Categories] = 'Personal' And [CompanyName] = 'Microsoft'"
NOT: The following code retrieves all personal contacts who don't work at Microsoft.
sFilter = "[Categories] = 'Personal' And Not([CompanyName] = 'Microsoft')"
If you are trying to use the Find or Restrict methods with user-defined fields, the fields must be defined in the folder, otherwise an error will occur. There is no way to perform a "contains" operation. For example, you cannot use Find or Restrict to search for items that have a particular word in the Subject field. Instead, you can use the AdvancedSearch method, or you can loop through all of the items in the folder and use the InStr function to perform a search within a field. You can use the Restrict method to search for items that begin within a certain range of characters. For example, to search for all contacts with a last name beginning with the letter M, use this filter:
sFilter = "[LastName] > 'LZZZ' And [LastName] < 'N'"