ExpressionParser Class |
Helper class for working with field reference expressions.
Field references can be used throughout platform applications with an expression containing markers for IField values of the form [<flags><key>] where <key> is a field Key and <flags> are zero or more modifier flag characters (see the corresponding FieldExpressionAttrs flags) specifing how the field value is to be represented:
- $ - DisplayText - Use the field's display text rather than its raw value (obtained via DisplayTextGet(DispTextFlags)).
- ' - AnsiQuote - AnsiQuote the value using AnsiQuote(String) (this is a single-tick character).
- ` - DoubleQuote - Enclose the field value in double-quote '"' characters (this is a back-tick character).
- # - Numeric - The value is a numeric value and should be rendered as zero "0" if the value is null/empty.
- < - UseOldValue - Use the OldValue if the field is dirty.
- & - UseCaption - Use the field's Caption instead of its value.
- ? - EscapeForUrl - The field's value should be escaped for use in a URL using ForUrl(String).
- @ - EscapeForHtml - The field's value should be escaped for use in HTML using ForHtml(String).
- ^ - ApplyDefault - Use the field's DefaultValue if the field's value is null/empty.
- + - EscapeForXML - The field's value should be escaped for use in XML using ForXml(String).
- * - RawValue - Use the field's value (obtained via Value), implied if no other option specified.
- ~ - ClientElement - Renders as a javascript expression accessing the field. Often combined with either '$' or '*' attributes to obtain the client-side display or raw values respectively.
- : - Optional - Value is optional and should default to zero or empty string, as appropriate.
- - - Guid - The value is a GUID value and should be rendered as the zero GUID "{00000000-0000-0000-0000-000000000000}" if the value is null/empty.
Field references are sometimes used in conjunction with "!fn" Embedded Functions which are resolved by the EmbeddedParser.
Inheritance HierarchyNamespace: NetQuarry
Assembly: EAP.Core (in EAP.Core.dll) Version: 2.0.0.0 (4.6.8.0)
SyntaxThe ExpressionParser type exposes the following members.
Constructors| Name | Description | |
|---|---|---|
 | ExpressionParser | Initializes a new instance of the ExpressionParser class |
Methods| Name | Description | |
|---|---|---|
| Equals | (Inherited from Object.) |
 | ExtractFieldKeys(String) |
Construct a set of keys for the fields referenced in the specified expression.
|
| ExtractFieldKeys(String, Boolean) |
Construct a set of keys for the fields referenced in the specified expression.
|
| ExtractFlags |
Converts a string of field expression flags to their corresponding FieldExpressionAttrs.
Field expression flags occur in field expressions immediately following the
opening square bracket.
|
 | Finalize | Allows an Object to attempt to free resources and perform other cleanup operations before the Object is reclaimed by garbage collection. (Inherited from Object.) |
| GetHashCode | Serves as a hash function for a particular type. (Inherited from Object.) |
| GetType | Gets the Type of the current instance. (Inherited from Object.) |
| HasReferences |
Determines if the specified expression MIGHT include Field References
by checking for the existence of any field reference prefixes.
See HasReferencesOrEmbeddedFunctions(String) to also check for Embedded Functions.
|
| HasReferencesOrEmbeddedFunctions |
Determines if the specified expression MIGHT include Field References or Embedded Functions
by checking for the existence of any field reference or embedded function prefixes.
See HasReferences(String) to only test for Field References.
|
| MemberwiseClone | Creates a shallow copy of the current Object. (Inherited from Object.) |
| Parse(String, String) |
Parse a field expression extracting its FieldExpressionAttrs and reference string. Flag characters,
if any, must precede the expression itself and any leading and/or trailing square brackets will be removed.
|
| Parse(String, String, String) |
Parse a field expression into its FieldExpressionAttrs and reference string. Flag characters,
if any, must precede the expression itself.
|
| PerformExpressionModification |
Modify a resolved expression per the specified FieldExpressionAttrs.
|
| ResolveReferences |
Common helper function to resolve a string of references, given a list of possible
replacement values (contained in property collection).
|
| ToNumericString |
Convert a supposedly numeric string into a validated numeric string. This method has two purposes:
|
| ToString | (Inherited from Object.) |
Fields| Name | Description | |
|---|---|---|
 | FieldRefFlags |
The set of valid field reference flags used in field reference expressions.
See FieldExpressionAttrs for a description of each.
|
| RefCaption |
The field reference flag signifying that the expression should be resolved using the field's caption.
See UseCaption.
|
| RefRaw |
The field reference flag signifying that the expression should be resolved using the field's raw value.
See RawValue.
|
Extension Methods| Name | Description | |
|---|---|---|
 | EqualValue |
Determines if the object value is equal to another object. If the two objects are null, then this returns true.
There is special handling for guid comparisons (since a guid could be a string formatted in up to 3 different ways).
If the special guid handling is not performed, then the object.Equals method is used.
(Defined by EAPUtil.) |
Remarks
Note that in many contexts, particular filters on pages and page elements, references to query parameters in the current request URL may be used.
These take the form [<flags>req.<paramy>] where the "req." prefix indicates that the value is to be obtained from the <param>
parameter in the current request URL.
See Also