P purchased property within D. Pursuant to a new land use ordinance, the property was zoned M-1, a manufacturing zone which permitted single-family dwellings. P's intent was to use the property for moderately priced single-family housing. D's ordinance requires consultation with the city planning commission, preparation, and submittal of a preliminary plan showing compliance with minimum requirements of the subdivision ordinance, and approval of both preliminary and final plans by the city planning commission. The commission rejected the proposed subdivision: (1) Development of the proposed residential subdivision was contrary to the land use ordinance and the city's master plan; (2) The access roads provided by the plan were inadequate; (3) The location of the railroad on three sides of the proposed subdivision made it an inappropriate site for housing. P unsuccessfully appealed the decision and then filed a complaint in district court. A restraining order was issued enjoining D from amending its zoning ordinance. The injunction was lifted on April 18, 1978, at which time a change in the zoning ordinance that had been enacted on January 19, 1978, became effective as it applied to P's property. The trial court held that P's proposed development was permissible under the zoning regulations in existence prior to January 31, 1978, that P had substantially complied with procedural requirements and had a vested right to develop the proposed subdivision, and that D was estopped from withholding approval of P's subdivision on the basis of the amended ordinance enacted after the application for subdivision approval had been submitted. This appeal resulted.