Class `FieldExpression` allows you to compute customized content snippets for each result returned by a search.

`FieldExpression` is defined in the module `google.appengine.api.search`.

## Constructor

The constructor for class `FieldExpression` is defined as follows:


class FieldExpression(name, expression)

:

    Construct an instance of class `FieldExpression`.

    For example,

    ```python
    FieldExpression(name='content_snippet',
                    expression='snippet("very important", content)')
    ```

    constructs a field expression that returns a computed field named `content-snippet` with each search result, containing HTML snippets of the `content` field that match the query `"very` `important"`.

    <br />

:

    Arguments

    name

    :   Name of computed field.

    expression

    :   Expression to evaluate and return.

    Result value

    :   A new instance of class `FieldExpression`.

    Exceptions

    TypeError

    :   A parameter has an invalid type, or an unknown attribute was passed.

    ValueError

    :   A parameter has an invalid value.

    <br />

## Properties

An instance of class `FieldExpression` has the following properties:

name

:   Name of computed field.

expression

:   String containing expression to evaluate and return.